Home >> truss spacing

Tag Archives: truss spacing

Thinking Stick Frame Rather Than Post Frame

Thinking Stick Frame Rather Than Post Frame

Reader BRAD writes:“Real question…I’ve been doing lots of reading and love this site. I am building a 40x60x14 this spring. I originally thought I was going to go pole barn and now I am thinking stick frame. Reason….1. I am going to have insulated concrete foundation with in floor heating piping installed right away. (mono slab). 2. I am planning on fully finishing the inside insulation electrical, etc. in the future. What I’ve seen with post frame is that they are cheaper to build initially but if you are planning on finishing the inside there is substantial lumber and framing that needs to be done for interior walls and interior ceiling. It appears “at the end of the day” a finished pole barn is not much cheaper than a stick frame. I also question if it would be a lot more time trying to frame an interior post frame with 16” o/c studs and finishing a ceiling with 4’ or longer truss spacing vs 2’ with conventional stick frame. I am doing all metal exterior with 2’ o/c stud purlins on side walls vs osb sheathing. I know you can spray closed cell spray foam but again that is more than triple the price vs bats and vapor barrier that you can only do with 24”or16” o/c framing.

Am I way off base on this theory or is there any truth to my thinking?”

Mike the Pole Barn Guru responds:
I just don’t see reason number one as a reason at all. A plethora of post frame buildings (my own included) utilize radiant in-floor heat. In order to stick frame, you are going to have to thicken your slab edges, or pour a continuous footing and stem wall, in order to provide adequate support for your now load bearing walls. This is going to result in added expenses for forming, regardless of your choice (before even considering extra concrete required). While anchor bolts for stud walls are relatively inexpensive, they do require some effort to be properly placed in order to avoid hitting studs and plates need to be drilled to account for them.

In order to stick frame without added engineering, your wall heights are going to be limited by Building Codes. To attach steel siding, you will need to add horizontal framing outside of your studs (scarily, I did see a builder post photos of vertical steel siding, screwed to vertical studs), resulting in two sets of framing, extra pieces to handle, cut and install. By using commercial style bookshelf wall girts in post frame, no extra framing is required in order to attach exterior steel siding and wall finish of your choice. As post frame buildings transfer gravity loads from roof-to-ground via columns, eliminating (in most instances) any need for structural headers.

Using prefabricated metal connector plated wood trusses, in pairs, directly aligned with columns (most often placed every 12 feet), does require ceiling joists to be placed between truss pairs. This can all be done on the ground, then cranked into place using winch boxes, with no need for other heavy lifting equipment.

When all is said and done, fully engineered post frame construction will always be more cost effective than stick frame, more structurally sound and afford a greater ability to super insulate, regardless of one’s choice of insulation systems.

This entry was posted in Pole Barn Structure, Trusses, Concrete, Pole Barn Questions, Columns, Pole Building How To Guides, Pole Barn Heating, Pole Barn Planning and tagged pole barn truss spacing, closed cell spray foam, truss spacing, stick frame, insulation, lumber framing, pole barn, purlins, osb sheathing on July 13, 2023 by admin.

Edge Dimples, Metal Truss Spacing, and Monitor Buildings

This Wednesday the Pole Barn Guru discusses reader questions regarding panels with “edge wave/dimples,” metal truss spacing for an ag building, and monitor building widths.

DEAR POLE BARN GURU: Good afternoon, on a few jobs we’ve had installed the lap leg on it has had edge wave/dimples along the panel, with no rhyme or reason as to where the dimples are. This is causing the panel to not lay 100% perfect and have small gaps along it as well if you look from the side. When looking at the panel on the ground it appears you do not see the wave/dimples. It is 29ga az50 galvalume painted, 3/4″ high rib exposed fastener ag panel. Do you know what could possibly be causing this? I attached a picture as well. Thank you! Tyler

DEAR TYLER: Most often this is caused by handling issues before steel is on ground at your jobsite – after first time I had to deal with it I made it a point to double check overlapping edges of all skids for damage before driver sped away to his or her next delivery. Any appearance of a wave on this edge and back on truck it went.

Your randomness issues appear to be from jobsite handling however they oftentimes can be bent back carefully by covering wave with a soft cloth and using a pair of pliers. Even if slightly over bent back, it will lay flat once screws are installed on side away from overlap.

DEAR POLE BARN GURU: Putting up a metal truss pole barn that calls for 12′ post centers and want to use 16′ centers for the truss using 16′ 2×6 for the purlins 30 cups per bay. Looking to get more length to barn this way. Minimum wind and snow load central Mississippi agriculture barn building housing mostly hay. Will this work or is 12′ max on metal truss bay width? 3 bays 16′ would garner me 50′ length with overhang or two 12′ bays on the end and 16 bay in middle would get me 42′ of length with foot overhang. Would either be sturdy enough for this application. TOMMY in ACKERMAN

DEAR TOMMY: Those welded up steel trusses are designed to support bare minimal loads at 12 foot on center. Spacing them any farther apart is nothing short of a recipe for failure. Also, unless you have access to some very high strength 2×6 for purlins, they would be over stressed in bending and deflect noticeably. If you want or need a longer building, invest in more trusses.

DEAR POLE BARN GURU: Monitor barns -is it crazy to think/have 14 foot “wings” and 24 wide center? Thinking 52 wide with 14-24-14 sizing. Seems most have narrower center. Is there a reason? STEVE in WEISER

DEAR STEVE: Not crazy at all, we have had clients with raised center of monitor as wide as 80′. Ultimately it comes down to what dimensions work best for your wants and needs.

Often monitor buildings are used for horse stall barns, where raised center is an aisleway. In this scenario 12-16′ center widths work very well for aisles.

This entry was posted in Budget, Uncategorized, Pole Barn Questions, Pole Barn Design, Building Styles and Designs, Constructing a Pole Building, Pole Barn Planning and tagged metal trusses, steel panels, monitor buildings, steel edge waves, steel overlap waves, wind and snow loads, monitor wing width, truss spacing on January 11, 2023 by admin.

Ceiling Insulation, Truss Spacing, and Custom Multi-use Barn

This Wednesday the Pole Barn Guru answers reader questions about best way to insulate a vaulted ceiling, truss spacing, and the possibility of adding a small living quarter to a horse barn.

DEAR POLE BARN GURU: With a vaulted ceiling, how do you insulate it if you plan to spray the tin roof with closed cell foam. Was planning on bat insulation on the lower cords of the trusses if needed. what about venting if you spray foam the tin roof? CHRIS in DORCHESTER

DEAR CHRIS: Saline County is located in Climate Zone 5A. As such conditioned buildings require R 60 attic insulation.

You can either:

Have a conditioned attic space – using closed cell spray foam at least two inches thick against underside of roof deck, then adding open cell spray foam or unfaced rock wool batts to get to required R value. This assembly will not be ventilated.

An unconditioned attic. If you have no other method of condensation control, then again place two inches of closed cell spray foam directly to roof steel interior. Vent eaves and ridge, then blow in R 60 of fiberglass across attic. Insulation baffles will need to be placed at eaves to allow for at least an inch of unobstructed air flow above blown in insulation.

DEAR POLE BARN GURU: Hello Mike, I have a question regarding a post frame building I would like to build. the size is 40′ x 32′ x 16′ with 6/12 roof pitch. I am planning to use trusses at 2′ foot centers. my question is regarding using 3 tab composition shingles for my roof covering (I have a HOA that will not allow metal roofs), what special considerations might I need to take with respect to where the trusses attach to the top of the post frame wall? the posts will be at 8′ centers and standard girts installed. I was thinking that perhaps increasing the dimensions of the top girt would be necessary. I would appreciate your thoughts on my intentions. I have enjoyed your YouTube videos as well. Sincerely MARK in CODY

DEAR MARK: Thank you for your kind words about our YouTube videos. https://www.youtube.com/user/HansenBuildings
Personally, I would place double trusses to bear directly upon columns spaced every 10 to 12 feet with purlins on edge, joist hung between truss top chords. This design results in fewest number of holes needing to be dug, as well as fewest pieces of materials to have to install. It also allows for wider door openings.

Doing as you propose, truss carriers (headers between columns to support trusses) would need to be adequately sized by your building’s engineer in order to carry imposed loads without failure or undue deflection.

DEAR POLE BARN GURU: Do you all have barns with living quarters? Not looking for a barndominium, per se, but a restroom with a shower and a living room in addition to 4 stalls and a tack room. we plan on staying there at first while we build the main house on the property, then use for guests or storage. SARAH in SARASOTA

DEAR SARAH: We have provided a plethora of barns with living quarters and every building we provide is custom designed to best meet our client’s wants and needs.

Typically, you should expect to have to two-hour fire separate barn from living area, meaning you cannot go directly from one occupancy to another without going outside in order to do so. For this reason, many of our clients have opted to have a roof only breezeway area between these dissimilar occupancies.

This entry was posted in Barndominium, Trusses, Ventilation, Insulation, Pole Barn Questions, Pole Barn Design, Professional Engineer, Constructing a Pole Building, Columns, Pole Building How To Guides, Pole Barn Homes, Pole Barn Planning and tagged truss carriers, truss spacing, living quarters, insulation, tack room, spray foam, Ventilation, horse barn on December 14, 2022 by admin.

Blown-In Insulation, Uplift Plates, and Truss Spacing

This week the Pole Barn Guru answers reader questions about better blown-in insulation on 3/12 pitch ceiling, a reader with uplift issues and how to prevent them, and some concerns about truss spacing at 8′ oc.

DEAR POLE BARN GURU: Hello, I have a 30×48 pole barn with scissor trusses 6/12 outer pitch 3/12 inside pitch. It has metal roof with dripstop. Trusses are 4’ on center and I was going to place metal on inside ceiling 3/12 pitch then place blown in insulation on top of that. Would it be best to use fiberglass blown in insulation instead of cellulose? I will be sure to place baffles on eaves for proper ventilation. Do I need any vapor barrier between the metal and insulation seeing as I have dripstop on roof metal? Thank You! DON

DEAR DON: Yes, use blown fiberglass rather than cellulose. Cellulose has fire retardant chemicals in it, when combined with excess moisture, it will prematurely decay steel liner panels (and cellulose is much heavier than fiberglass). Unless you are located where there are over 8000 annual heating degree days, you should not have a ceiling vapor barrier.

DEAR POLE BARN GURU: The wind lifted my pole barn up about a foot on one end last spring and hasn’t settled back down. Wondering how to get it back down to earth? STEVE

DEAR STEVE: Your building has sadly become an experiment to show what happens when adequate uplift provisions have not been made during construction. Hopefully your building has been insured for replacement costs – so you can have this work hired out.

In order to successfully get a ‘return to earth’ your building should be disassembled back to at least a point where no column uplift is detectable – including removing uplifted columns from ground.

Re-dig all offending post holes.

Add an uplift plate on on side of each column at bottom. https://www.hansenpolebuildings.com/2018/12/uplift-plate/
Stand columns in holes, so bottom of column “floats” roughly 8″ from bottom of hole. https://www.hansenpolebuildings.com/2015/04/floating-poles/
Pour bottom 18″ or more of each hole with readi-mix concrete.

Re-frame building, replacing any damaged lumber or trusses.

Before putting steel panels back on building, confirm no slots have been created in panels due to tearing around screw shanks when building lifted. Replace any damaged panels.

DEAR POLE BARN GURU: We are having a 30 x 50 barn built, and our builder just put up the trusses. It is a stick frame barn on a slab and the trusses are spaced 8′ apart. The concern is that there are not enough trusses. It looks like a “pole barn” but is on a traditional slab identical to our house and the “poles” are not buried. Trying to find information on truss spacing has been difficult. Both dad and uncle think it is not enough and have traditional construction backgrounds. Please help. ASHLEY in ANDERSON

DEAR ASHLEY: Provided your building’s trusses have been engineered to adequately support loads when spaced every eight feet, there is nothing wrong with them. https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/
What is wrong is it appears this building is being constructed without site specific engineer sealed structural plans. Chances are better than most you will have some future challenges due to this. Roof purlins should be attached to trusses using Simpson or USP brand joist hangers. Truss bottom chord bracing is missing and truss heels should be attached to walls with an uplift connector adequate to resist your roof flying away during a high wind event.

This entry was posted in Insulation, Rebuilding Structures, Pole Barn Questions, Building Styles and Designs, Roofing Materials, Pole Barn Planning, Pole Barn Structure, Trusses, Ventilation, Footings and tagged blown in fiberglass insulation, Uplift, pole barn truss spacing, Uplift Plates, truss spacing, insulation on November 23, 2022 by admin.

Weather Resistant Barriers, LVL Notches, and Design Ideas

This week the Pole Barn Guru answers reader questions about weather resistant barriers, a caution to not attempt to notch LVL rafters, and a recommended design solution for a new build.

DEAR POLE BARN GURU: We are in process of designing our barndominium with hoping to start building next spring. Do you have a recommendation as to what water resistant barrier (WRB) to use with closed cell spray foam? Planning on using a standing seam metal roof and wainscot siding at this time. I know that a reflective barrier is useless without an air gap behind it. Using spray foam prevents its use. I’ve researched several, like zip system, Tyvek, and others. Thanks for answering my question. GREG in CARROLL

DEAR GREG: In your climate zone I would typically not recommend using spray foam other than as two inch thickness applied directly to steel roofing and/or siding in order to control condensation. This does result in having to mechanically control humidity as your building will now “dry” to inside. As standing seam steel does not provide shear resistance, it must be installed over solid decking – and you can spray foam directly to this decking underside.

In any case, it is not recommended to use closed cell spray foam applied to any WRB. For extended reading: https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/

DEAR POLE BARN GURU: I got a pole barn I’m putting up. The purlins were designed to run over end rafter bit that makes eve low. Can a 1 ½” x3 ½”(2×4) notch for outrigger for eave support and run end rafter up like others in the center. Notch would be 1 ½” deep on an 11 ¾” lvl. One in center span and one at top of roof. This is on the shed roofs only. MIKE in RAVENSDALE

DEAR MIKE: Absolutely do not cut or notch into your end rafter. You need to lower end rafters to allow purlins to go over top of end rafters without any notching.

While you are at it – have your building’s engineer recheck those shed rafters and purlins closest to main endwall to confirm they are adequate for snow drift loads. Usually purlins closest to endwalls have to be much closer together to adequately support those loads.

DEAR POLE BARN GURU: I want to space my poles 8′ apart and use to 2×12, one inside and one outside at the top to place standard trusses on the top so i can add an insulated ceiling in it. Any comments on this, and how deep do my posts have to go into the ground? LARREN in DAVIS CREEK

DEAR LARREN: Personally, I would throw away your proposed design solution.

In most instances, you are better served with sidewall columns spaced every 12 feet. Use a true two-ply truss, aligned with every sidewall column (https://www.hansenpolebuildings.com/2018/09/true-double-trusses/) and notched in. Trusses should be engineered to carry a ceiling (bottom chord dead load – BCDL). Use five (5) psf (pounds per square foot) for a steel ceiling and 10 psf if sheetrocked. Between bottom chords of pairs of trusses, joist hang 2×6 #2 24 inches on center.

In any case, raised heel trusses should be utilized to allow for full depth of insulation from wall-to-wall. https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/
Column depth will be determined by engineer who is designing your plans. They need to be deep enough to go below frost line (not an issue in California) as well as to resist overturning and uplift. Building dimensions, applied wind loads and soil bearing capacity will all impact depth of holes.

This entry was posted in Ventilation, Insulation, Building Interior, Pole Barn Questions, Professional Engineer, Pole Barn Design, Building Overhangs, Pole Building How To Guides, Pole Barn Planning, Barndominium, Pole Barn Structure, Trusses and tagged overhangs, weather resistant barriers, Design Solutions, standing seam, truss spacing, LVL, notching rafters, spray foam on September 7, 2022 by admin.

Price Per Square, Scissor Truss Spacing, and Column Spacing.

This week the Pole Barn Guru answers reader questions about our “best guess at price per square…” for a Hansen Building Kit, spacing for scissor trusses, and if there is a national code for post spacing in a barndominium.

DEAR POLE BARN GURU: What is your best guess at price per square foot range materials and labor to build a Hanson Pole Building these days? STEVE in MAPLE PLAIN

DEAR STEVE: All Hansen Pole Buildings kits are 100% custom designed to best meet wants and needs of our clients, as such – we do not price per square foot, but rather by actual dimensions and features, taking into account climactic conditions at each individual building site (snow load, design wind speed and wind exposure). While most of our clients are doing DIY, largely due to a lack of quality building erectors, fair market value for labor is typically roughly 50% of what your building kit investment is (not including any concrete).

DEAR POLE BARN GURU: I’m hoping you can give me some advice. A pole building 30 wide with scissor trusses pitched at 10/12 out 5/12 inside closed cell insulation finished on the inside with 1″x8″ pine run horizontal ….will spacing the trusses on 4′ centers be alright? The building is in central Iowa zip code 51537.

Thank You so much!! JOHN in HARLAN

DEAR JOHN: These trusses may or may not be adequate for your needs, depending upon loads and spacing they were designed for.

The engineer who sealed your building plans is responsible (by Code) to review your truss drawings to ensure they comply with his or her design specifications as outlined on their plans. They also are to create a permanent bracing plan to satisfy all needed truss and building needs. This bracing plan must be shown on these same plans.

A caution, steeply sloped trusses impart a large horizontal wind load and building sidewall columns must be appropriately analyzed to insure structural adequacy. Columns specific to a 4/12 roof slope, may not be strong enough to carry these added loads. Again, your engineer can (and should) confirm.

DEAR POLE BAR NGURU: Hi, Barndominiums, is there a national code about how far apart the poles should be? 10 ‘ or 8′? Here in Kentucky, I’m under the impression that the poles have to be 8’ apart. Am I correct? Regards DAN in MURRAY

DEAR DAN: You would be incorrect. Poles (actually columns) are inanimate objects and can be spaced at whatever distance their size and grade is capable of supporting using sound engineering practice. Our engineers recently designed a building for one of our clients with columns every 18′ and many years ago, I did one with columns spaced 24 feet on center. In most instances (depending upon climactic loads and door/window locations) columns every 12 feet are most economical.

This entry was posted in Building Colors, Trusses, Professional Engineer, Columns, Pole Barn Questions, Pole Barn Design, Barndominium, Constructing a Pole Building, Pole Barn Planning and tagged truss spacing, post frame pricing, post spacing, price per square foot, scissor trusses, columns spacing, cost per square foot on May 25, 2022 by admin.

A Building Addition, A “Coverup,” and Advice for an Acquired Building

Today the Pole Barn Guru answers reader questions about adding on to an existing pole barn with use of 24″ oc trusses, covering old wooden sliding doors with steel, and advice regarding erecting an acquired Cuckler steel building.

DEAR POLE BARN GURU: Trying to plan on a 36’x80’x12′ addition to an existing 30’x40’x10′ pole barn. This new barn will be insulated with an insulated ceiling and have a shingled roof to match my existing barn. Because I am not planning on a steel roof and instead, OSB sheeting and asphalt shingles and because I am needing an insulated ceiling I do not believe it makes sense to install double trusses at 12′ apart. I have no need for roof purlins and ceiling joists if I put single trusses at 24″ O.C. The material & labor costs to install purlins & ceiling joist must out-weigh the cost saving of having 4 less roof trusses per 12′ span. JOE in FENNVILLE

DEAR JOE: Thank you for your interest in a new Hansen Pole Building. We certainly can design your building with trusses placed two foot on center on top of truss carriers (headers) between columns. Your Building Designer will be reaching out to you shortly.

DEAR POLE BARN GURU: I have an old wood barn that I overlapped with metal. I completely redid the double sliding doors which are 6 feet wide by 12 feet tall. They are 2×4 wood frames that I plan to place metal on top of. I am having a very difficult time finding out how to trim the doors so none of the wood is exposed on the outside face. I have seen what is called F channel, but is it made to fit dimensional lumber as in 1.5 inches? JEFF in OWNESBORO

DEAR JEFF: I would have ditched lumber frames for prepainted metal frames and been done with it, plus metal will never twist and warp like wood and your door frame would be significantly lighter (not too late to regroup). Still not convinced? Any steel roofing and siding roll former can bend trim to match any dimensions, so you can have created exactly what you are looking for.

DEAR POLE BARN GURU: When we purchased our land, we acquired an old cuckler steel clearspan building we would like to erect as our garage. The steel is in great shape and will make an awesome garage with some work. All we have are the trusses, side beams and z purlins so I will be supplying new 2×10 roof joists, metal roofing and siding. I’ve got a hardware list put together with all new grade 8 bolts, some 1″, and I’m fine with assembly but we need some engineering plan to be able to get a building permit. How can we go about reverse engineer this enough to give us what we need to apply for a permit? Also the sidewalls on this building are 8′ and we are trying to figure out if we want to raise the sidewall, what is the best way to do that?

Building info: model C20 Rigid frame 40×60

We found an old Cuckler building guidebook. We have the building on page 12 and 13. (see attached) TAMI in STEAMBOAT SPRINGS

DEAR TAMI: Your attachment did not make it, but no worries. I am going to connect you with Hansen Pole Buildings’ primary third party engineer – if it can be made to work, he can do it. I will caution you, Building Codes and accepted engineering practice have changed dramatically since this old Cuckler Building was designed. It is possible you own nothing more than a pile of recycling. Best of luck to you.

This entry was posted in Lumber, Pole Barn Questions, Pole Barn Design, Roofing Materials, Constructing a Pole Building, Pole Barn Planning, Trusses, Rebuilding Structures, Professional Engineer and tagged sliding door parts, building addition, 24" O.C., sheathing steel, door trim, cuckler steel building, truss spacing, engineering on March 1, 2021 by admin.

Splash Boards, Roof Loads, and Truss Spacing

This week the Pole Barn Guru answers reader questions about shrinkage of splash boards installed wet, roof load capacity, and truss spacing for an RV storage building.

DEAR POLE BARN GURU: I have two questions (related) regarding splash boards and concrete floor top. My splash boards have been in place for quite a while, and have actually shrunk (they were quite wet when nailed in place). There are several that are not over 7 inches wide. I’m going to end up with only 3-1/2 inches of splash board above the concrete. Is this sufficient? The tops of the splash boards are very level, and I’m thinking of attaching treated 2x4s on the inside to screed against. It would be easier (and probably more accurate/consistent) for me to measure 3-1/2 inches down from the top rather than up from the bottom of the splash boards.

Also, wondering if there is a benefit to placing 3 x 1/4 inch galvanized lag bolts, 1 inch into the splash boards from the interior side 1 or 2 feet apart, to “anchor” the splash boards to the slab?

Thanks so much for sharing your experience and insights! GREG in COLVILLE

DEAR GREG: As long as you are measuring from a level point and top of your concrete slab will be below bottom of your base trim you will be all good with measuring down 3-1/2″ from splash board tops. While I have not done it personally, I know more than one person who has used a pressure preservative treated 2×4 to screed against as you describe. At a minimum it should be rated UC-4A (ground contact) for treatment.

There might be some small benefit to be gained by using a mechanical attachment of splash boards to your slab. As to how much, I have not seen any studies to verify.

Thank you for your kind words and please remember to send me progress photos!

DEAR POLE BARN GURU: Do you know how much weight per square foot the roof of a pole building can hold? My building is 64’ x 36’, if that matters. ROBERT

DEAR ROBERT: Weight per square foot (psf) will be dependent upon what your building was engineered to support. Every set of engineer sealed building plans is required to list all loads to be supported. Usually this will be specified by a value for sloped roof snow load (Ps) for roof plane live loads. Dead loads (actual weight of structure and supported materials) should also be listed.

DEAR POLE BARN GURU: I’m wanting to do a pole barn to park my RV under for the winter. My question is can I use a single truss spaced at 10’? Do I need to use two trusses per post? ERIC in BONNERS FERRY

DEAR ERIC: Without knowing how far you intend to span with your trusses it is difficult to provide a definitive answer. Boundary County does not require building inspections, so even though you are in an area of extremely high snow loads – risks end up being upon you as a new building owner.

While a single ply truss may work, in most instances your investment into true double trusses (nailed face-to-face as a pair) is minimal. Double trusses provide greater reliability as your probability of having two adjacent trusses having a same ‘weak link’ is small. Bracing requirements are also reduced when a pair of trusses are utilized.

Even though you may not need a building permit, I would strongly encourage you to only erect a fully engineered building. Protection for your RV is only going to be as good as what your building is designed for.

This entry was posted in Pole Barn Design, Trusses, Concrete, Professional Engineer, Lumber, RV Storage, Pole Barn Questions and tagged truss spacing, roof loads, lumber shrinkage, double trusses, RV Storage, splash boards on November 23, 2020 by admin.

Truss Spacing and Design

Truss Spacing and Design for Sheathed Post Frame Roofs

In most instances, there is not a structural or Code requirement for solid roof sheathing (plywood or OSB – Oriented Strand Board) to be placed below through screwed roof steel for post frame buildings. In some cases, clients look upon this as being an easier installation when doing a DIY build. For others, it is about providing a thermal break to eliminate underside of roof steel condensation. And a few look towards minimization of potential hail damage.

Reader CARROLL in PORTER writes:

“ Wanting to build Pole Barn that is about 35’x80’x12′ My question is, if I want to install 1/2″ decking plywood or OSB decking with underlayment and metal panels how far apart will I need the trusses to be center to center or what kind of truss design will I need? I guess it could be a 4/12 or 5/12 pitch if that helps any.”

Provided you have adequate available space, you may want to tweak your footprint dimensions in order to optimize your return for your investment. As steel comes in three foot widths and lumber in two foot lengths, your most cost effective dimensions of length and width will be multiples of six feet. In your instance, I would recommend 36 feet wide and 84 feet long.

With this said, I would place a single truss on each endwall and a two ply truss every 12 feet to align with your sidewall columns. Purlins can be placed on edge, using engineered steel joist hangers, between each set of trusses and spaced every two feet to support your sheathing. Whether plywood or OSB, panels are best installed running up roof from eave to ridge (perpendicular to purlins, parallel with truss spans). If not using synthetic underlayment, you should use 30# asphalt impregnated paper (roofing felt). With Hansen Pole Buildings, we purposefully design all trusses spanning 40 feet or less with a greater than minimum requirement top chord dead load – in order to accommodate those who want to install solid sheathing.

This entry was posted in Pole Barn Questions, Pole Barn Design, Roofing Materials, Pole Barn Planning, Trusses and tagged purlins, roof sheathing, OSB, top chord dead load, roofing felt, 30# asphalt impregnated paper, 1/2" decking, 1/2" plywood, truss spacing on July 23, 2020 by admin.

Upstairs Conversion, Building Plans, and Basic Buildings

This week the Pole Barn Guru answers questions about converting an upstairs space in a pole barn to a living space, Plans only packages, and a basic building kit.

DEAR POLE BARN GURU: I have a 30×30 pole barn with upstairs 2 story shingle roof. Want to convert it to a living space for my grandchildren and their mom my son passed away she needs a place to live.

Thank you RICH in CREAM RIDGE

DEAR RICH: You should begin by finding out if your local Planning Department will allow you to convert this barn into a residence. Once you assured they will be happy, you should engage a Registered Professional Engineer to determine if it will be structurally adequate to be used as a residence.

DEAR POLE BARN GURU: Hello, Do you sell plans for pole barns? I live in Canada and work as a social worker working with at risk youth. My wife and I use horses as a way to work with children who have difficulty in communication, self-esteem, anger and other concerns that prevent them from reaching their full potential.

The struggle we have is that everything we do is outside which means we simply cannot do anything during the winter and early spring months.

I have talked to several builders and truss makers who insist that trusses must be spaced every two feet so for a 100 X 60 pole barn I would need 51 at a cost of $30,000; factoring in all of the other costs it is simply out of our reach. I have read that you suggest trusses can be spread further apart and one of the builders I have spoken to said I should ask for some plans and he would see what he could do, however is very skeptical.

I sincerely hope you can assist and thank you in advance.

Many thanks. PETER in ST. GEORGE

DEAR PETER: Thank you very much for your interest. We are not a plans service, we do supply engineer sealed plans with all of our buildings (along with complete installation instructions). Currently we are unable to design to Canadian Building Code, however we hope to incorporate this option in 2020. Right now, all of our Canadian friends are ordering buildings designed to U.S. Codes. Trusses most certainly do not have to be every two feet. Depending upon your snow load, I would expect to see a pair of trusses every 10 feet. We do have a sample plan available on our website: https://www.hansenpolebuildings.com/sample-building-plans/

DEAR POLE BARN GURU: Hello, are the base prices listed for the kit only or does that include shipping, tax and installation? NATE in EFFINGHAM

DEAR NATE: Thank you for your interest in a new Hansen Pole Building. Prices listed at https://www.hansenpolebuildings.com/pole-barn-prices/ are for engineer sealed plans, complete materials package delivered to your accessible site, 500 page step-by-step installation manual and unlimited free technical support. Sales tax varies by state (and sometimes city or county) and we only collect in states mandating we do so.

While our buildings are designed for an average physically able person to assemble their own beautiful new building, should you be not so inclined, installation services are available through our Independent Builder Network.

This entry was posted in Barndominium, Pole Barn Questions, Pole Barn Planning, Trusses, Lofts and tagged Plans, Conversion, living space, basic building, truss spacing, building kit on April 6, 2020 by admin.

Things Roof Truss Manufacturers Should Ask

Things Roof Truss Manufacturers SHOULD Ask, But Don’t Always

I didn’t just fall off of a turnip truck yesterday, even though there are a few who may doubt my claim!

Prefabricated metal plate connected wood trusses and I became close friends back in April of 1977. Yes, we had electricity then and no, I did not watch space aliens build Egypt’s pyramids. Eventually I owned and operated two truss plants for 17 years. I know it may sound odd, but I did learn a couple of things.

Most of us do not know to ask (or tell) what we are not asked. When Hansen Pole Buildings’ Wizardress of Ordering Justine gives information to our trusted truss suppliers, all of these factors below have been incorporated into our order. This insures your trusses will be adequate to handle loads being placed upon them.

Chances are you (as well as most other post frame building kit suppliers and/or contractors) have not taken all of these into account. In failing to do so, your building may not do everything you want it to do not only today, but also years from now (or could even fall down and go boom).

Here we go:

Span from outside of wall to outside of wall. Eave overhangs are not considered as part of a span.

Desired slope(s) – with scissor trusses to achieve a vaulted ceiling or added center headroom, provide an interior or exterior ‘must have’ and other slope will be determined from ‘must have’ slope.

Spacing (ideally you will be using double trusses spaced directly on columns) rather than going into some lengthy dissertation on truss spacing, please read this article: https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/.

Overhangs on eave sides (measured parallel to ground), as well as beyond endwalls. Why is beyond endwalls important? For sake of discussion assume single trusses placed every two feet, unless specified and designed otherwise and end truss in this scenario can only support a foot of overhang past an end. Single trusses placed every four feet can support a maximum two foot end overhang.

Roofing material and any solar or rooftop arrays. How many psf (pounds per square foot) must your trusses support? Steel roofing is fairly light weight. If using shingles, Code requires incorporation of enough load capacity for a reroofing down the road.

Is roofing over purlins, sheathing? Maybe sheathing AND purlins. Whichever is your case, these weights need to be accounted for as top chord dead loads.

Ceiling? If not now, ever? One of my most asked questions is in regards to adding ceilings in existing post frame buildings. At a bare minimum to support steel liner panels bottom chord dead load should be three psf, for gypsum wallboard (sheetrock) five psf. Last year Hansen Pole Buildings opted to increase bottom chord dead load for all trusses spanning 40 feet or less to five psf. We do not frankly do a very good job of promoting the benefits of this feature.

If attic is insulated, weight of ceiling material, ceiling joists and attic floor insulation.

Design wind speed and exposure. More buildings fail from roofs blowing off, than from snow. Depending upon Code year and version, wind speed may be expressed as Vult or Vasd. There is a difference and whoever is going to build trusses needs to know. If you do not fully understand differences between B and C wind exposure, learn quick: https://www.hansenpolebuildings.com/2012/03/wind-exposure-confusion/

Heated or Unheated? There is a factor relating to whether your building will be heated and it influences design snow load. Heated buildings help melt snow off.

Overall building dimensions: width, length, height above grade. These factors impact wind design.

Risk Category – How your building will be used impacts design snow and wind loads. Buildings with infrequent human occupancy have less risk and can be designed for a greater probability of failure in event of an extreme weather event.

Energy heels for full depth attic insulation? If ever insulation might be blown into a dead attic space for purposes of climate control, to be effective it should be full depth from outside of wall to outside of wall. For extended reading: https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/

Siding material (so proper gable truss recommendations can be made). If supporting other than roll formed steel siding, end truss probably will require vertical studs. Without a continuous wall beneath an end truss, it must be ordered as a structural gable.

Is the building fully enclosed, partially enclosed or open? This will again influence wind design.

Are you interested in parallel chords with a heel height to create a vaulted ceiling? You can get the same slope inside and out with this method.

Done right you would be offered options to increase load carrying capacities against either wind, snow or both. This is true value added design. Builders most always want bare minimums, while people who are doing DIY homes or barndominiums are most likely to increase capacities. If in doubt – own the last building standing!

When I was building trusses I had extremely high expectations of my truss staff, we always wanted to offer designs to exceed our client’s expectations.

Too many factors to juggle? You do not have to fret with an engineered Hansen Pole Building. Please call 1(866)200-9657 today.

P.S. Remember, I have no current interest in any truss manufacturing facility so please don’t contact me for truss prices, thanks.

This entry was posted in Steel Roofing & Siding, Trusses, Post Frame Home, Barndominium, Shouse, Pole Barn Design, Roofing Materials, Pole Barn Structure and tagged pounds per square foot truss support, truss spacing, top chord dead loads, wind speed and exposure, risk category, roof slope, attic insulation weight, scissor trusses, building span, overhangs on eave side on February 26, 2020 by admin.

Ag Exemptions, Truss Spacing, and Concrete Vapor Barriers

This week the Pole Barn Guru discusses ag exemptions for building permits, the effect of spacing trusses at 12′ or more, and concrete vapor barriers.

DEAR POLE BARN GURU: Do I have to have a permit to build one poll barn on Ag land? DANIEL in PIERSON

DEAR DANIEL: Many jurisdictions nationwide exempt true agricultural buildings, on agriculturally zoned land from building permits. A practice I disagree with entirely – as it places these buildings at risk of failure due to under design of critical structural components.

To find out if you would need a permit, or not, is going to take a phone call from you to your local Building Department and asking them.

DEAR POLE BARN GURU: Guess this is where to ask questions? We are planning a pole building 40X72 and would like to space the Trusses at 12ft or more? I see you say no problem but what would it take for this? Is it heavier trusses or heavier purlins? Just not sure the requirements for more spacing. Thanks! BRIAN in WARRENSBURG

DEAR BRIAN: You have come to the right place. Changes in truss and column spacing impact more than just having “heavier” trusses. Your entire building structure should be reviewed and sealed by a Registered Professional Engineer to properly incorporate all applicable loads for your site. Just a few possibly affected areas are column footings, column depth and diameter, amount of concrete around base of columns, uplift prevention, wall girts, roof purlins, truss bracing….just to begin with.

Each set of building dimensions and loading condition can have their own best design solution from both economic and functionality aspects. Hansen Pole Buildings’ Instant Pricing system™ allows for nearly instantaneous pricing of various truss spacings – down to fractions of inches!

Please read more about post frame (pole) building truss spacing here: https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/.

DEAR POLE BARN GURU: Does the vapor barrier under the concrete slab of a pole barn need to cover the poles and splash boards at the perimeter of the concrete? Or do I just lay the vapor barrier on the ground and not up the sides? I am using 10 mil Stego. Thanks for any help! JARROD

DEAR JARROD: You should extend vapor barrier up columns and to top of splash planks.

Information on Stego™ vapor barriers can be found here: https://www.stegoindustries.com/stego-wrap-vapor-barriers

This entry was posted in Trusses, Ventilation, Concrete, Pole Barn Questions, Pole Barn Planning and tagged truss spacing, Ag Exempt, building permits, ag exemptions, concrete vapor barriers on October 28, 2019 by admin.

Is the Double Truss System Stable for the Midwest?

Is a Double Truss System Stable for the Midwest?

Reader SHARON in NORTH DAKOTA writes:

“Dear Pole Barn Guru,

I have attached some pictures of a 62×96 pole barn with 12ft sidewalls. I am rather ignorant about truss systems, but this one looks atypical to others I have seen. What type of truss system is this, and is it stable for the midwest? How are your truss systems different?

Thank you for your time and knowledge.”

Mike the Pole Barn Guru responds:

What you are looking at is a “double truss” system, where two roof trusses are physically joined side-by-side with the use of mechanical connectors (most often nails). It is absolutely stable for anywhere in the world. The most common Hansen Pole Building design utilizes the double truss system, typically with sidewall columns spaced at 10, 12 or even wider column spacing depending upon applied wind and snow loads as well as door locations. In the case of the photos you have sent, the roof purlins were placed over the tops of the trusses and staggered every other bay, this precludes the ability to pre-drill the roof steel, which would have minimized (or eliminated) the possibility of a roof leak caused by a misplaced screw. The Hansen Pole Buildings’ double truss system utilizes engineered steel connectors to attach the roof purlins to the sides of the roof truss top chords, as opposed to merely attempting to adequately nail through purlins to the tops of the trusses. The superior holding power of this connection resists wind uplift forces which could otherwise tear a roof off and send it swirling off like Dorothy’s home in The Wizard of Oz.

The most popular article I have written is on truss spacing – you can read it here: https://www.hansenpolebuildings.com/2011/06/pole-barn-truss-spacing/.

A caution – in the photos you have supplied, the trusses have knee braces, which could lead to a collapse if not engineered and accounted for within the truss design. More on knee braces here: https://www.hansenpolebuildings.com/2012/01/post-frame-construction-knee-braces/

The benefits of double truss systems vs. single truss systems include:

1- Fewer holes to dig for truss bearings – with columns every 12 feet, it reduces holes by 1/3rd.

2- Fewer columns to have to set.

3- Reduces total number of boards and trusses having to be handled and installed by as much as 50%.

4- Eliminates possibility of the one single weakest truss failing and pulling the balance of the roof down behind it.

5- Reduces the need for lateral bracing – a properly connected together double truss is twice as stiff in resisting buckling in the weak direction.

This entry was posted in Pole Barn Questions, Pole Barn Design and tagged truss spacing, knee braces, column spacing, steel connectors on April 20, 2018 by admin.

Can 2×4 Roof Purlins Span 12 Feet?

Reader DAVE in MICHIGAN writes: Hi, I saw on your webpage the Pole Barn Guru stated the trusses could be spaced 12’ apart (I called and was told it is a double truss one on each side of a post that is on 12’ centers). That is exactly what I have, double trusses on each side of a post on 12’ centers.

My question is can I use 2” X 4” on edge spaced 16” or 12” apart? I intend to have a metal roof on top.

Thanks for your help!

DEAR DAVE: My preferred method of post frame construction actually places the two trusses face-to-face nailed together and notched into one side of the column. In this fashion they truly act as a two ply member. Spacing them on each side of the column causes the trusses to work independent from each other and takes away the advantages of the true double truss system (load sharing and minimization of truss bracing).

Could one use 2×4 roof purlins in this system?

Let’s do some math and find out. (You can brush up on bending moments here: https://www.hansenpolebuildings.com/2012/09/bending-moment/)

Here is the formula for calculation of a roof purlin:

[(COS of Live load + dead load) X (COS of the purlin spacing) X (purlin span squared)] / [8 X (Sm = Section modulus of the member) X (Duration of Load = 1.15 in areas with snowfall) X (Cr repetitive member factor of 1.15 where members are 24″ on center or less)] = Fb (Fiberstress) required

The COS of the Live Load is due to us only having to check for bending about the strong axis of the member as the purlin is restrained in bending in the weak axis direction by the roof steel.

The COS of the purlin spacing is because the load on the purlins is vertical and the purlin spacing is with the run of the roof.

For sake of discussion we will assume a minimal roof snow load of 20 psf (pounds per square foot) and a 4/12 roof slope.

Dead load will be the actual weight of the roof steel and the roof purlins.

[(20 psf X .949) + 1.5 psf) X (12″ X .949) X (11.625′)^2] / [8 X 3.0625 X 1.15 X 1.15] = 972.75 psi

HemFir has a base Fb of 850 psi multiplied by the size factor of 1.5 = 1275 psi

In bending, 2×4 #2 purlins would work at 12″ on center, however I personally would not want to walk on top of them. Without even running the calculations, I would say there is a good chance the 2×4 purlins will not make the deflection criteria required for a roof framing member supporting steel.

Rather than having 2×4 purlins every 12″ it would make far more sense economically to use 2×6 purlins every 24″. Less expensive (1/3rd less board footage of lumber), fewer pieces to handle, fewer joist hangers to have to attach and only one half as many screws to attach the roof steel.

This entry was posted in Pole Barn Questions, Pole Barn Design, Trusses and tagged pole building roof purlins, pole building truss spacing, pole barn purlin spacing, truss spacing, pole barn trusses on May 9, 2017 by admin.

Sharing the Pole Barn Blame

Sharing the Blame

Welcome to 2017!

As you may recall, 2016 ended with me sharing an email from a builder who is constructing a new Hansen Pole Building and may possibly be a legend in his own mind.

Our company policy, when a challenge arrives, has always been to begin by looking to see what, if anything did we do wrong. In this particular case, we (and yours truly) share in some of the blame.

For you, gentle reader, I will paint a picture of the building in question, so you may get a better feel for the entire process.

The building is a 40 foot clearspan in width, 100 feet long with an eave height of 16 feet and five inches. It is designed under the 8^th edition of the Massachusetts State Building Code, with a 90 mph (mile per hour) design wind speed and a 50 psf (pounds per square foot) design flat roof snow load.

It features 12 inch enclosed overhangs on all four sides, as well as three 14 foot wide by 14 foot tall overhead doors on one sidewall.

The most practical design solution actually (which is a rare case) turned out to be based upon the traditional “East coast” style of post frame construction, with a single truss spaced every four feet on top of “truss carriers” (beams) spanning sidewall columns generally every eight feet (other than at the overhead door locations).

This building happens to be narrow in width in relationship to length (1 to 2.5 ratio) and is fairly tall. As such, the wind load was great enough to exceed the shear resisting capacity of the steel roofing in the eight feet closest to each endwall.

In order to carry the load, the building was designed so the trusses in the affected areas would have a traditional ¼ inch butt cut (educate yourself on what a butt cut is here: https://www.hansenpolebuildings.com/2015/05/truss-butt-cuts/), while the balance of the trusses would have 11/16 inch butt cuts. This would allow for the top of all truss carriers to be placed at the same height, and 7/16” OSB (Oriented Strand Board – https://www.hansenpolebuildings.com/2013/10/osb-versus-plywood/) to be installed on top of the lower heel height trusses.

Pretty darn skippy sounding ……. Until we get to tomorrow!!

Yep – yet another cliff hanger!!

This entry was posted in Pole Barn Design, Building Overhangs, Steel Roofing & Siding, Building Contractor, Trusses and tagged post frame construction, builder, truss carriers, trusses every 4 feet, truss butt cut, truss spacing, building contractor on January 3, 2017 by admin.

Let’s Talk Snow Load

Even though it is now May – the heavy snowfalls in the New England states this past winter have left many with concerns. Here is an actual conversation, between a client who recently invested in a new Hansen Pole Building kit package, and our Technical Support Department:

Client: “Good Afternoon,

Quick couple of questions. The plans look like the wall girts for this project are the “commercial wall girt” design (Option 1)?

I was initially under the impression that Option 1 was just for the design where the “Roof Purlins /joist are hung vertically from the side of the Trusses”. I did not know that Option 1 also included a commercial wall girt design.

Is it necessary to use the commercial wall girt design if I have Option 1: “Roof Purlins /joist are hung vertically from the side of the Trusses” design? OR could the Wall Girts be just 2 x 4s nailed on the outside of the Support Posts?

Just curious-

After answering these couple of questions, I will log back in and approve the drawings.”

Building Code Snow Loads No snow yet, but we will get to it. Here is the response:

Thank you very much for your investment in a new Hansen Pole Building. Every building we provide has each member and connection structurally checked for adequacy under the most stringent Code provisions. Other than for very small column spacing, this means wall girts will need to be placed “book shelf” style, in order to be Code conforming.

Here is some reading which may prove helpful: https://www.hansenpolebuildings.com/blog/2012/03/girts/

Now we will get literally knee deep into the snow:

“The structural support poles on my drawing are at 14 ft. Not 10 ft, and not 8 ft. This is my concern. (I read the guru blog). 14 feet between poles with double trusses, still doesn’t cut it when I could have 5 feet of snow on the roof. This barn will be located in Northern Maine.”

Thank you for your concerns. Your building has been designed for the loading recommended for your area, 50 psf ground snow load – which you acknowledged as being verified by you as adequate with your Building Department, prior to your order being placed.

If you are planning upon having five feet of snow sit on top of your roof, then we would recommend increasing the snow load capacity of your roof to somewhere in the vicinity of 100 psf (this would equate to a ground snow load of approximately 173 psf). To increase the roof snow load by this 346% would add $xxxx to your investment.

Please advise accordingly.

“After some further research, I have found that the recommended ground snow load for my county in Maine is 90 PSF. Please advise on new plan design and associated incremental cost to my project to accommodate.”

Just want to confirm you feel this will be adequate for your particular site, as a 90 psf ground snow load will support about 30-32″ of snow on the roof. If indeed you believe a greater depth may be placed upon it, it would behoove to design accordingly.

“The liability I am putting on myself here is tremendous. Does Hansen Pole Barns have any culpability for designing this building for snow load correctly? Because I don’t know. I am at a loss, I am not an engineer. We have little if any Code Enforcement in this county. But I know we get a boat load of heavy wet snow and the building will be in a sheltered area with not much winter sunlight.

My builder originally said it was 50 PSF (As he thought that was the code). But I don’t think knows. When I looked at the design that I was sent, (and I am a believer in engineering, as I am a non-certified Mechanical Engineer), I know the design is not adequate. So, I started to research on the internet. The best I can come up with is what I found on the internet. SEE ATTACHED

I am located in New Vineyard ME, Franklin County 04956. Every town that is near me shown on the attached “Ground Snow Loading” document is listed as “Case Study”, so I am guessing at the 90 PSF. (because everything around me is either at 90 or 100 PSF

Looking for advice”

Although you may have read this previously, it may prove good background: https://www.hansenpolebuildings.com/blog/2012/02/snow-loads/

Based upon your information, we’d recommend a change in the Ce factor from 1.0 to 1.2. This effectively increases the design roof snow load by 20%

Along with this, here are some Pg options (in psf) to pick from (as well as the investment to increase) and the approximate depth of snow on the roof for each:

90   $ 2252       38″
100      2498       42″
110      2578       46″
120      3169       50″
130      3368       54″

Me personally, I tend to go for over design – I prefer to be the one who owns the last building standing when the storm of the century hits.

This entry was posted in Building Styles and Designs, Professional Engineer, Pole Barn Design and tagged truss spacing, Building Code, professional engineer, pole building column spacing on May 7, 2015 by admin.

Dear Guru: Trusses at 12′ Work?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays. With many questions to answer, please be patient to watch for yours to come up on a future Monday segment. If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU:I am looking for more information on roof trusses. I would like to know how double roof trusses at spacing of 8′ or more is as good as or better structurally than 4′ or 2′ spacing. The long spans between joists is something I have not seen before. I don’t need an answer immediately, I’m still planning my pole barn.

You’re web site is great, and has answered many of my questions. Keep up the good work.

Thank you. ONLY IN ORANGE

DEAR ONLY: Thank you for your question and for planning things in advance so your new building ends up being ideal for you. There are several facets in the answer to your question.

Looking at the trusses themselves – a single truss spaced every four feet and ½ of a pair of trusses spaced every eight feet are going to be carrying the exact same amount of load.

Now let’s imagine loading the roof beyond the actual design capacity (it does happen when the once in 100 year storm decides to visit). In a single truss system, when the weakest truss fails due to extreme loading – there is a pretty fair chance the rest of the roof is coming down along with it, as each successive single truss becomes overloaded due to the failure of the previous truss.

In a double truss system, each truss is securely attached to its partner. The probability of both of these trusses having the exact same weak point is infinitesimally small. In the event of the storm of the century, chances are very good the double truss system will still be standing, after the single truss system has failed.

With a true double truss system (where the trusses are attached directly face-to-face and not spaced apart by blocking), the truss pair is also twice as stiff against buckling in the weak direction as a single truss. This allows for a significant reduction in the amount of lateral bracing required for bottom chords and web members – more cost efficient and quicker to construct.

The real beauty of the double truss system is when the trusses can bear directly upon the columns – as opposed to a “truss carrier” (aka header). Connections often become the failing point in buildings, so the more they can be reduced in number and complexity, the less chance of a catastrophic failure.

I’ve heard more than one engineer or building inspector complain about the challenge in trying to get the connections specified on the plans for carriers to columns, actually done correctly in the field!

With trusses directly aligned with the columns – there are no truss carriers to deal with. The columns are taking all of the downward load, making the truss to column connection one of merely overcoming uplift.

Double trusses on widely spaced columns (typically 10 to 14 feet apart) with roof purlins on edge between them, also allow for easier application of wider sidewall doors – frequently without the need for structural headers. This becomes especially convenient when doors are added after the initial building construction.

DEAR POLE BARN GURU: I’ve just received delivery of the materials for my new Hansen Pole Building. I notice your lumber provider sent 8×8 pressure preservative treated columns, instead of the 6×8 called out for on the plans. While I appreciate the ‘under promise, over deliver’ my question is this – do I connect the trusses to the columns by notching them in as the plans show, or should the notches be made deeper into the columns. VEXED IN VIRGINIA

DEAR VEXED: I can imagine it looks as if you have been sent the entire tree – certainly they will not being going anywhere in a wind storm!

There are times when our suppliers will provide free upgrades, sometimes without clueing us in even! Although it often does not make a difference structurally or cosmetically – it is always best to check, just in case.

With your particular set of circumstances, it turns out you can install the trusses either way, without any negative structurally effect, or compromising assembly.

Make sure to send photos as you go, and be extra careful with lifting – we don’t want to hear reports of any strained body parts!

This entry was posted in Pole Barn Questions, Trusses and tagged truss spacing, trusses at 2', trusses at 4' on August 25, 2014 by admin.

Dear Pole Barn Guru: Can I Use Spray Foam Insulation in My Pole Barn?

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: In northern Idaho, just east of Coeur d’Alene, I had a pole barn put up without insulation figuring I would build 2×6 walls between the posts and insulate with batts and then plywood the walls later for a work shop. Can spray foam be used instead? Could I frame 2×4 walls instead of 2×6? Can it be sprayed onto the metal siding and roof without any negative effects showing up later? I will have a heater in there, but probably not on full time. QUIRYING IN COEUR d’ALENE

DEAR QUIRYING: Can you use spray foam? The answer is yes, however it is probably the most costly choice, and the Building Code requires any spray foam to be covered with non-combustible material (e.g. gypsum wallboard).

For the walls, you could frame a non-structural 2×4 studwall, holding it flush to the inside of the columns, and place batt insulation between the studs. The studs do not have to be the same depth as the insulation, and in doing so, you will eliminate a thermal bridge.

Beware, less costly (per inch of thickness, not R value) open cell foams are permeable to moisture – so condensation could become an issue. To obtain an R-19 rating from spray foam, be prepared to spend around $3 to $4 per square foot of insulated area.

While spray foam is relatively light weight, always check with the manufacturer of the roof trusses and the Registered Design Professional (RDP – engineer or architect) who designed your building to verify the weight of the insulation being added will not compromise the structural integrity of the building.

DEAR POLE BARN GURU: I sent in three pole barns that i am looking to get a quote for. my families barn just recently burned down a few days ago due to undetermined causes. We lost our animals in the fire which was devastating. Our pigs and chickens were our livestock and our food. We need to get a barn up and built soon to get our farm running again. I have a few questions about this, first off if i go ahead and purchase this kit how does it get delivered to my house. Second, if this is purchased is the supplies all in one kit that you ship out or is it a list a what we need and i have to get it? please get back asap thank you. NEEDY IN NEW YORK

DEAR NEEDY: I am deeply sorry for your losses. Fire is so devastating.

When you order from us, the materials are delivered to you via truck.

You are purchasing from us the design, the complete 24″ x 36″ blueprints which are specific to your building and show where every board is placed. Not only to we provide all of the materials for construction, but we give you detailed instructions as to how to assemble everything.

DEAR POLE BARN GURU: What is your standard design practice to accommodate a wider O/C truss? Double the truss? Or increase the truss member sizes?

VASCILATING IN VERSAILLES

DEAR VASCILATING: Our most common practice design in general is a system using doubled trusses spaced most commonly every 12′ (although spacings 10′-16′ are also very common). The doubled (or more technically “ganged”) truss system affords some safety not found in single truss systems – as multiple trusses physically connected to each other all for true load sharing. The probability of two or more connected trusses having the exact same weak point is phenomenally low – reducing the risk of a catastrophic failure in an extreme loading situation. Ganged trusses also require less bracing than single trusses, adding to ease of installation, as well as lower costs and a “cleaner” finished appearance. It also may mean no cumbersome (and expensive) truss carriers. Lastly, if you put overheads in a sidewall, having the double trusses mean you could put as wide a door as 12’, and have plenty of room to put in a hoist system to lift a vehicle between the sets of trusses.

Vascilating then responded:

Thanks for the quick response. I assume, then, the practice is to utilize 12′ 2×6 purlins placed on edge on top of those trusses?

Is the spacing of 12′ the same for an attic truss? I recently got a quote from Hansen for a gambrel building with which I intend to have attic trusses. Is it common practice to finish a room using the knee walls of those trusses?

Dear Vacilating:

Every client gets my individual and undivided attention for as long as they need to get their questions answered.

The snow load will dictate purlin size, but they will be 2×6 or larger, joist hung between the trusses. Attic trusses will be the same, however may be more than just a 2 ply truss depending upon the span and load. Most typically people will finish those spaces with a knee wall.

Unless you are absolutely married to the gambrel look, the most efficient and cost effective design for multi-story space, is to just design a multi-story building. For about the same cost, you can get full room height from sidewall to sidewall

This entry was posted in Insulation, Pole Barn Questions and tagged double trusses, Foam insulation, single trusses, trusses on 8', wide span trusses, truss spacing, pole building insulation, pole barn insulation on March 31, 2014 by admin.

Dear Guru: Can My Pole Barn Trusses Handle a Ceiling Load?

DEAR POLE BARN GURU: I have a question regarding truss loads, specifically ceiling loads, for a pole barn. I know you have touched on this before, but I was hoping for a little more detail.

I recently purchased a property that came with an existing pole barn, and other than a few material ratings I cannot find any data on the trusses (no manufacturer tags, etc). The building is 32×48, and the trusses 4/12 pitch with 2×6 top cord, and 2×4 bottom cord and webbing, on 4′ centers. I want to add a steel ceiling, plus insulation and lighting. By my math I am looking at a dead load of 2-3 lb/sq ft, including the weight of the bottom cord of the trusses.

I have done a lot of research on the subject, and it seems that it is common in pole buildings to have trusses spaced much wider than 4′ (8’+ seems common). Is the tighter spacing a indication that these trusses should support a 2-3 lb/sq ft dead load for ceiling and insulation? If you were specing trusses for my requirements, how would you design them? If these trusses are not sufficient, what sort of reinforcement would be required?

One of the only bits of data I have been able to find is this page https://www.pole-barn.info/gable-roof-trusses.html, where toward the bottom it lists a 30′ span with the same lumber sizes as my trusses. While it says “no ceiling” it also lists a bottom cord dead load of 5 lb/sq ft, which would be plenty for what I have planned. BAFFLED IN BOZEMAN

DEAR BAFFLED: The spacing of the roof trusses has no influence upon their load carrying capacity. In reality, trusses spaced 12 feet on center could easily have a greater ceiling load carrying capacity than ones placed even every two feet!

As a starting point, you should assume the trusses are NOT designed to support dead load weight of anything other than the trusses themselves, required bracing and minimal wiring and lighting.

The size and or grade of the truss chords as well as the webs and their quantity, and the size of the roof truss plates may not be adequate to carry the weight of the ceiling load. It’s not as easy as just knowing the size or spacing of each part, but rather it’s more of how all the parts function together in any configuration. In other words, it’s a formula with many parts which change the final answer of “yes” or “no”.

The only safe way to make sure your new ceiling doesn’t end up on the floor with the rest of the roof following it, would be to hire an engineer to confirm the trusses are adequate to support the ceiling load, and to design a repair for them, if necessary.

DEAR POLE BARN GURU: We are builders, putting up a Hansen Pole Building currently. It is large enough so the main clearspan building and attached shed had to be shown on two different pages of the blueprints. Anyhow, we made a mistake on setting the poles. Where we are looking at the 4 posts going across up by the “matchline” we have the left sidewall posts set correctly but the 2 main building posts and the right side shed post are set incorrectly. We ran a string line but the workers ended up setting those 3 posts on the other side of the string line.

I am wondering if there is an easier solution than pulling out the posts. We have a lot of concrete in the holes and it would be hard to get them out. Could we fir out the left sidewall posts and go out and buy longer purlins? ERRANT

DEAR ERRANT: While this doesn’t happen often, you are not the only person to have this problem. In this particular case, you are constructing an engineer certified post frame building, which means any deviation from the plans is going to have to be approved by the engineer. This is going to mean time delays and the expense of paying the engineer.

Even if it was not an engineered building, using purlins for a span which is now 5-1/2 inches greater could overstress the purlins in bending. While 5-1/2 inches may not sound like much, in the design calculations for the purlins, the span is squared.

I’ve had to pull out concreted in columns before, and it isn’t fun. Best method I found was to use a backhoe or loader, wrap a chain around the column and lift it out. Fairly fresh concrete can be chipped away from the column and the process of setting the three columns can begin again.

I’m sorry I don’t have an easier solution, but you will be much happier with the outcome if you do reset the posts. And all in all, it may end up being far less expensive as well, in both time and materials. As I said, I’ve done this myself, so I am right there with you. The good news is, once you reset the posts, just knowing you have things all “in order” will make the project run smoothly from here on out

This entry was posted in Pole Barn Structure, Trusses, Pole Barn Questions and tagged trusses, truss design, truss spacing, pole barn ceiling on October 7, 2013 by admin.

Single Truss System: Purlins Laid Flat

Before any of my readers drop their teeth due to me saying something I don’t exactly extol… is easy….read on!

I’ve spent the last few days in Michigan – where I am being told no Building Official would EVER approve of a pole building designed with double trusses spaced 10 or 12 feet on center and 2×6 or 2×8 purlins on edge. To the contrary, I’ve been involved in the design of about 15,000 buildings designed exactly this way. Throughout the Western United States, the typical post frame construction utilizes the concept of pressure preservative treated columns, spaced 10, 12 or even 14 feet on center, with two ply trusses, aligned with the sidewall columns. Literally hundreds of thousands of buildings have withstood snow loads to upwards of 200 pounds per square foot (psf) and wind speeds far over 100 miles per hours (mph).

The originally patented post frame (pole building) design concept utilized columns spaced every 12 feet. Even the unimpeachable source of all knowledge (Wikipedia) references columns spaced every 12 feet (https://en.wikipedia.org/wiki/Pole_buildings).

In post frame construction, roof purlins are the members running the lengthwise direction of the building, either placed on top of, or between the roof trusses (or rafters), to attach the roof steel or other roof sheathing to.

To the good folks in Michigan, the only way to construct a pole building, is to place the columns every eight feet. Truss carriers (basically headers) are then run from column to column. The trusses are installed on top of the carriers, every four feet.

This four foot truss spacing, allows for 2×4 roof purlins to be placed flat on top of the trusses. These purlins are attached by driving nails through the wide face of the purlin, into the tops of the trusses. It does make for a fairly easy purlin install (other than dimensional lumber typical runs about ¾ of an inch over length, so every purlin must be trimmed), and it gives a big wide surface (3-1/2 inches) to run screws through the steel roofing, into the purlins.

Like any system, there are some downsides – and my opinion is this method has some significant ones, which outweigh the positives.

In comparing to my idea choice of construction, this method requires 50% more holes to be dug. It takes half again more trusses and involves handling about double the number of framing members. Granted, often the framing members are smaller, but handling is still handling.

Structurally, there do exist some issues. The great majority of building failures are from connections – either inadequate, or improperly installed. The fewer connection locations, the less places for a potential error.

The trusses every four feet, columns every eight, results in purlins having to be connected to trusses, trusses to truss carriers, truss carriers to columns. Lost is the direct truss to column connection provided by them being aligned with each other.

In a single truss system, if one truss fails due to extreme loads, the balance of the roof is sucked down behind it. The face-to-face connected double truss system, creates a redundancy where no two adjacent trusses share the identical weak link. This load sharing prevents many would be failures.

With the single truss system, as each truss is only 1-1/2 inches wide, requires double the lateral bracing against buckling of a double truss (three inch wide system). Again, more pieces, more connections, more possible locations for failure.

And one more thing – I mentioned nailing the steel to the purlins on the 3-1/2” face as being an easy target to hit. However – what about nailing the 2×4 purlins where they come together over a single truss? You now have two purlins butting into each other, sharing that 1-1/2” space. The chances of missing the truss beneath, or splitting either the end of the 2×4 and/or the ¾” space on the truss are….pretty high. Another connection failure.

And back to the Building Official issue – our company has dozens of clients all across the state of Michigan who have been granted Building Permits and are enjoying their buildings with double trusses and wall columns spaced every 12 feet. Never be able to obtain a permit? Never is a big word, and it just is not the case.

This entry was posted in Building Styles and Designs, Constructing a Pole Building, Pole Barn Structure and tagged truss spacing, double trusses, flat roof purlins on August 13, 2012 by admin.

Pole Barn Truss Spacing Rerun

Happy 4th of July!

On holidays, I take a day to relax, and “re-run” some of my most highly read blogs. From over a year ago, today’s subject has been viewed close to 8,000 times. Yes, that’s 8 thousand. So here you go, for what I consider one of the hottest topics in pole building design: Pole Barn Truss Spacing

What do you mean they aren’t 2 feet apart?

Back in the day (early 1990’s) I was on the National Frame Builders Association (NFBA) Board of Directors. One of my fellow board members from the Midwest wanted to take a peek at how pole barns were constructed in the West, so I invited him out for a tour.

After spending a day looking at several of our building projects, his comment to me was, “The inspectors in our area would never let a pole building be constructed with roof trusses placed every 12 feet”.

Twenty years later, I beg to differ. Hansen Buildings has buildings in each of the 50 states and all of them have roof trusses on what my board member friend would describe as being “widely spaced”.

Modern truss design is highly computerized. Enter the span of the truss, bay spacing and load conditions and the engineering programs will design a truss spacing which will meet the design criteria. The lumber and steel plates the trusses are constructed from, have no idea how far apart they are going to be placed. They are inanimate! Yet, somewhere in the deep, dark reaches of history, lies the theory wood trusses must be spaced no more than 24” on center, or maybe 48”, or perhaps even eight or ten feet? The reality is, there is no magic number.

While H. Howard Doane is credited with being the innovator of the modern pole barn, it was his Agricultural Service farm manager, Bernon Perkins, who is credited with refining the evolution of the modern pole building to a long-lasting structure. It was Perkins who pioneered roof purlins being placed on edge. With this design change, roof trusses could be placed 12 feet apart, making it possible for roofs to support the loads to which they would be subjected.

I’ve had roof truss manufacturers try to convince me it is impossible to place wood trusses at spacings of over every 4 feet. Their defense is, “Our engineers will not allow us to”. The manufacturers of the steel roof truss plates (also referred to as gussets or Gang-nails), provide the engineering design for pre-fabricated wood trusses. Their programs will allow for trusses to be placed on 12 foot or even 16 foot centers, and their engineers will place their engineer’s seal on the drawings to verify.

The practicality, cost effectiveness and ease of construction of pole buildings is based upon efficient use of the fewest amount of materials, to do the most work, within safe engineering design. Hundreds of thousands of pole barns are in use today with truss spacing every 12 feet, or even more. They stand as a tribute to the ingenuity of modern pole building design.

This entry was posted in Pole Barn Structure, Building Styles and Designs and tagged roof trusses, truss spacing, pole barn trusses, Pole Building Design on July 4, 2012 by admin.

Building Design: Best Client Line Ever

Sometimes a client will put forth a statement which says more than anything I could ever write.

Bob, one of the Hansen Pole Buildings Building Designers, was talking on the phone with one of his clients this morning. Bob shared this with me:

“Competitor was trying to tell my client that more posts and trusses are better than our system. Client wasn’t buying it and told the guy “Listen Pal, I’m not looking for the best price per pound, I’m looking for the best design.””

For the most part, I have never looked upon myself as being a great innovator, when it comes to pole buildings. But, I have always felt I was blessed with the ability to look at how others do their structural building designs and do an impartial analysis of them.

The buildings Hansen Buildings provides today, barely resemble the ones I first designed and sold back in 1980 at Lucas Plywood and Lumber in Salem, OR.

By looking at what other people do which is good, then trying to make those things better (and incorporate those improvements), my firm belief is we have created the best possible value for the dollars invested by our clients.

In the case of the quote above – certainly we could design to place posts at any spacing desired. In most instances, spaced every 12 feet turns out to be the most efficient from engineering vs. cost standpoint. The side benefit is there will be fewer holes to dig. Unless one would happen to be part gopher, most are like me – we hate digging holes. With a passion. In many cases, the “more posts” are smaller in size or lower strength posts…..in which case, what was the point?

More trusses do not a stronger building make. Having spent what seems now like a past life either building, selling, designing or owning in the prefabricated roof truss industry, I do know just a little bit about it. Whether a truss is placed every 24 inches or a pair of them is placed every 12 feet, the trusses are designed for the given snow and wind loads – at the spacing they will be placed at. Connections are an issue, most building failures come from connection failures. The more individual trusses, the more individual truss to bearing support locations, the more the probability of one of those connections being under designed or improperly installed (either of which could result in a catastrophic failure).

At the end of the day, it is truly about the best building design, not the best price per pound.

This entry was posted in About The Pole Barn Guru, Pole Barn Structure and tagged Pole Building Design, truss spacing on May 4, 2012 by admin.

Pole Barn Truss Spacing

What do you mean they are not 2 feet apart?

Modern truss design is highly computerized. Enter the span of the truss, bay spacing and load conditions and the engineering programs will design a truss which will meet the design criteria. The lumber and steel plates the trusses are constructed from, have no idea how far apart they are going to be placed. They are inanimate! Yet, somewhere in the deep, dark reaches of history, lies the theory wood trusses must be spaced no more than 24” on center, or maybe 48”, or perhaps even eight or ten feet? The reality is, there is no magic number.

36′ long garage with 12′ bays

While D. Howard Doane is credited with being the innovator of the modern pole barn, it was his Agricultural Service farm manager, Bernon Perkins, who is credited with refining the evolution of the modern pole building to a long-lasting structure. It was Perkins who pioneered roof purlins being placed on edge. With this design change, roof trusses could be placed 12 feet apart, making it possible for roofs to support the loads to which they would be subjected.

The practicality, cost effectiveness and ease of construction of pole buildings is based upon efficient use of the fewest amount of materials, to do the most work, within safe engineering design. Hundreds of thousands of pole barns are in use today with trusses spaced every 12 feet, or even more. They stand as a tribute to the ingenuity of modern pole building design.

This entry was posted in Pole Barn Structure, Uncategorized, Pole Barn Planning and tagged roof trusses, truss design, truss spacing, wood trusses, design criteria, modern pole building on June 24, 2011 by admin.

enable JavaScript

1.866.200.9657

Latest Blog Posts

View All

Tag Archives: truss spacing

What will you use your

building for?

Approximate

building dimension

Your building. Your way.

Your building. Your way.

Can we text you to setup

appointments?

Are you a

robot?

Your request has been received!

Thank you!

There has been an

error!

Most Viewed Blogs

Latest Blog Posts