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Concrete, Steel Gauges, and Skylights

This Wednesday the Pole Barn Guru answers reader questions about volume of concrete needed to support a 300lb sign, pros and cons of both 26 gauge and 29 gauge steel, and replacing skylight panels.

DEAR POLE BARN GURU: I need to know how to calculate how much concrete would support this sign at 10ft with a 6 inch metal pole sign weighs 300lbs. BILL in TACOMA

DEAR BILL: Required amount of concrete will be based upon design wind speed and Exposure where sign will be placed, height of sign above grade and surface area of sign. You would be best served to reach out to a local Registered Professional Engineer, who can provide a sealed design for you (may be required by your permit issuing authority as well).

 

DEAR POLE BARN GURU: For steel roof panels and siding, what are the pros and cons of both 26 ga. and 29 ga. panels? Do the 29 ga. panels have a higher steel yield strength (80 ksi)? TOM in SMITHVILLE

DEAR TOM: Cons of 26 gauge steel roofing and/or siding are added investment and lower steel yield strength (usually 50 ksi or less). For more thoughts on this discussion, please see https://www.hansenpolebuildings.com/2020/11/do-barndominiums-need-29-gauge-steel/

 

Skylight WarningDEAR POLE BARN GURU: We need to replace some sky light panels on one of our older sheds. The roof and current panels are on 12″ center ribs. Do you have sky light panels that will fit my building DAN in ALMA

DEAR DAN: Sadly you are now faced with deterioration issues coming along with fiberglass panels placed in roofs. We provide panels with high ribs every nine inches on center. I would recommend you visit with the ProDesk at your nearest The Home Depot, with exact measurements of your steel profile, as they may be able to order in what you need.

This entry was posted in Roofing Materials, Constructing a Pole Building, Footings, Rebuilding Structures, Professional Engineer, Skylights, Pole Barn Questions, Pole Barn Design and tagged , , , , , , , on by .

Rubble Trench Foundations

Rubble Trench Foundations for Post Frame Homes?

My social media friend and loyal reader TRENT in NAMPA writes:

“Hi Mike, Ii would like your thoughts on some foundation ideas I have for post frame homes. The main purpose I am trying to achieve is to have perimeter concrete at the base of the building while reducing the cost of a standard stem wall foundation. This would allow you to insulate slab edge at the interior side, giving the building the look of having a more standard foundation. The option of making a raised floor crawl space, think of an old craftsman home when they did not excavate crawl spaces down below grade. Not sure if this all makes sense or not. Idea#1 bore typical 48+ inch depth holes for column footings. Dig a perimeter trench for a rubble trench foundation footing, pour a concrete grade beam with rebar and fill column footings at the same time. Use wet set brackets or bolt down style. Idea #2: dig a rubble trench foundation footing, pour a concrete grade beam with enough size/width to take the load off columns, mount columns to grade beam with metal brackets.”

Mike the Pole Barn Guru says:

Other than for looks, I am unsure of why one would want to go through efforts of having a concrete perimeter. I am not seeing why your suggestions would not work (other than bolt down brackets as they do not resist moment loads), just not maybe a most economical design solution.

We have provided numerous post frame homes over crawl spaces. Almost universally, no excavation has been done other than to level the site. With a raised wood floor, you can either leave crawl space unconditioned and insulate between floor joists, or condition space and insulate the perimeter wall below floor.

For slab on grade applications, a two foot deep trench can be dug around the perimeter, bore the balance of hole in the bottom of the trench (in our case, usually our total hole depth is 40″ with a 16-18″ deep concrete bottom collar). After columns are placed and splash planks are installed, R-10 EPS insulation can be attached to the inside of splash planks (not required in Climate Zones 2 or less), with top of insulation at top of slab, then down vertically two feet. At the base of vertical insulation (in Climate Zones 4 and greater), use the same insulation to go out horizontally two feet. Backfill trench with compactable material and call it a day. If concrete piers and wet set brackets are desired, square forms can be fabricated out of R-10 EPS to insulate piers.

This entry was posted in Footings, Barndominium, Pole Barn Questions, Concrete and tagged , , , , , , on by .

Post Frame Plywood Slab-on-grade

Post Frame Plywood Slab-on-grade

As concrete and excavation costs have increased steadily buildings are more frequently turning to slab-on-grade foundations. These assemblies require less concrete and labor than full basements and have a number of advantages over crawlspaces: better thermal performance, much lower risk for water and animal intrusion, and lower maintenance overall. Slab-on grade foundations also make universal design easier to achieve.

In our ongoing quest to improve residential post-frame construction methods, we’ve embraced a number of new approaches to slab-on grade foundations, one of those approaches is concrete-free slabs.

WHY WE DITCHED CONCRETE

REDUCED EMBODIED CARBON

Concrete has a high amount of embodied carbon, and companies like ours specializing in high-performance, environmentally conscious construction are always looking for innovative ways to use less of it. Roughly 40% of all United States greenhouse-gas (GHG) emissions come from our buildings, 11% from carbon embodied in materials used to make those buildings.

One biggest single contributors to GHG emissions is concrete, responsible for 8% of total emissions on our planet. So it makes sense to reduce not only energy amounts used in operating our buildings but also concrete amount we use to build them.

FEWER DELAYS AND MOISTURE REDUCTION

A plywood slab is not only more environmentally sound than a full concrete approach, but it offers a number of practical benefits too. D-I-Yers can build slabs themselves, saving on costs and allowing to better control timelines, avoiding delays due to subcontractor schedules and more. 

Unlike concrete, plywood slabs do not load significant moisture into building envelopes during curing processes.

HASSLE-FREE FLOORING

Another big advantage of a plywood slab is finished flooring can be installed directly onto it—no different than installing flooring on a plywood-and-joist floor. To install flooring on a concrete slab a vapor barrier must be applied over top with additional accommodations—such as wood sleepers and a plywood subfloor—depending on flooring chosen.

To make a plywood slab as durable as possible, choose a vapor-permeable flooring for slab’s largest areas. This allows any incidental moisture—from spills, toilet overflows, or whatever else happens above floor—to dry to interior and not build up in plywood. This said, we feel comfortable using impermeable flooring such as tile in smaller areas (kitchens and baths, for example) as long as it’s installed over a decoupling membrane to allow slab to flex and move below it and as long as there are adjacent permeable areas for plywood to dry to.

Bottom line: plywood won’t degrade as long as it has more of an opportunity to dry than it has potential for retaining moisture.

 

Start off on right footing

Building codes in many climate zones (3 or greater) require a minimum R-10 thermal break at concrete slab edges, where up to 60% of heat loss occurs. Compared to concrete, however, a plywood slab-on-grade has very little thermal loss at edges because it’s only 1-1⁄2 in. thick, and it’s wood. One could reasonably argue standard level of slab-edge insulation isn’t as necessary with a plywood slab-on grade. However, making this argument to your local building inspector might not be worth the accompanying headaches; as code has no guidance on anything other than concrete slabs.


LAYER 1: STABLE SOIL IS AN IMPORTANT FIRST STEP: First layer is native, undisturbed soil or engineered fill slab bears on. Most post frame buildings have no interior point loads, all bearing is on perimeter columns and their footings, and slab has no structural function. When we have a building with point loads or load-bearing walls on the interior, add interior footings, just as done with a concrete slab.

LAYER 2: CRUSHED STONE ACTS AS A CAPILLARY BREAK Second layer is a minimum four inch compacted, 3⁄4-in. crushed stone with no fines. Its primary function is to act as a capillary break, preventing moisture from being wicked up through the slab and into the building. This second layer also functions as a “pressure field extender” for the soil-gas ventilation system, with perforated pipes either passively or actively keeping radon from entering home, depending on local requirements.
 

LAYER 3: Gravel keeps things level under concrete-free slab

On a concrete-free slab-on grade, add a 2-in. to 3-in. 1⁄4-in.-minus gravel layer above capillary-break stone. This layer is much easier to screed level and flat so foam-insulation layers can be set in full contact without any voids or settling (this could create bouncy or uneven floors). Set a laser line on wall columns for reference and use a grading rake to get gravel close to level; checking with a tape measure. After this use a 2×4 as a screed, working it back and forth to set the grade perfectly flat, with top even with pressure preservative treated splash plank bottom.

LAYER 4: Rigid foam eliminates cold feet

Run rigid insulation horizontally under the entire slab. It’s not very costly to do in comparison to usual approaches, and  barndominium owner benefits are significant. First is comfort. People don’t want to feel cold underfoot, and they tend to complain if they do. An insulation full layer under the slab mitigates this problem significantly. Just as importantly, there is a big benefit in energy efficiency. For a floating plywood slab, this continuous insulation layer is essential, providing a flat, stable surface for floating T&G plywood floating raft. Use two layers of one inch thick EPS foamboard, oriented perpendicular to one another with seams offset to ensure minimal air gaps.

LAYER 5: 10-mil poly blocks moisture migration through concrete-free slab

Fifth layer—above insulation and directly below slab itself, is a polyethylene sheet acting as a Class 1 vapor barrier. This vapor barrier isolates concrete-free slab from ground and water and vapor it contains. Climate regardless, ground relative humidity always approaches 100%. If this layer were omitted, concrete or plywood would draw moisture into the building, inviting rot, mold, and humidity issues.

Using a 10-mil polyethylene sheet is a big reason concrete-free slabs are a durable, long-term approach. It’s critical to use compatible tapes for sealing seams and to ensure complete adhesion. Any penetrations, such as plumbing or radon vents, must be taped completely from pipe to poly without gaps, folds, or other sloppy work. Fill gaps around plumbing penetrations with canned spray foam, and tape those areas carefully

LAYER 6: Two plywood layers is last step to finish concrete-free slab before interior walls go up

Sixth and final layer, resting on vapor barrier, is material creating this concrete-free slab. Plywood is standard 3⁄4-in. T&G CDX subfloor material. Pressure-treated plywood is not only unnecessary but would add chemicals and VOCs to the interior environment. Install two layers, with the second set perpendicular to the first and joints offset. 

Leave a 1⁄2-in. gap between outside edges and perimeter EPS insulation or splash plank to allow T&G plywood to expand and contract. These two layers are allowed to float on layers below and are joined together with construction adhesive and 1-1⁄4-in. screws, sized so they don’t penetrate the vapor barrier below.

This entry was posted in Barndominium, Insulation, Pole Barn Design, Pole Building How To Guides, Pole Barn Planning, Pole Barn Structure, Pole Barn Homes, Post Frame Home and tagged , , , , , , , , , on by .

Being a Fan Fan

Being a Fan Fan

Reader TOM in MACOMB writes:

“Hello, I have a 24 x 40  pole barn built last summer. It has a base layer of 10” of sand and 4’ of crushed concrete on top. This sat exposed for several months until the building was erected,it was a wet summer. The building was finished in August and has a thin vapor barrier under the metal roof. As soon as the nights started turning cool moisture started dripping from the ceiling, especially from the 3 crystal panels. This building does have a gutter with good drainage. The moisture is coming from the ground as any plastic set on the ground overnight will result in heavy condensation underneath. So with that said I am hoping this issue is simply leftover moisture that will eventually dry up in time. However mold is developing and things are rusting. I would like to speed up or help the moisture leave the building. It does have soffit vents and ridge vent. Finally to my question. Can I put in an exhaust fan or a giant ceiling fan or both to help this process? I wasn’t sure which may be better, power vent on the roof or in the gable would be better. Or perhaps a 96” ceiling fan would be enough to push air through the ridge vent. Although the vent is covered with snow in the winter as this is in northern Michigan. Thanks in advance for any advice.”


Mike the Pole Barn Guru

My educated guess is your building’s concrete slab on grade does not have a well sealed vapor barrier underneath. If this is indeed true, you need to start by removal (or minimization) of your moisture source – put a good sealant on your slab’s surface.  There are other things to be done once ground thaws, we will get to them in a moment.

A powered gable exhaust fan will help to get moist air out from inside your building. Whether your proposed exhaust fan will be adequate or not will be dependent upon its CFM (cubic feet per minute) capabilities. You will probably want to plan for around 10 air exchanges per hour. If you have a 14 foot high ceiling, then 24 x 40 x 14 = 13,440 cubic feet (plus area above eave height at 4/12 slope is another 1920 cubic feet) X 10 times / 60 minutes per hour = 2560 CFM.

Come Spring – grade away from your building at least 10 feet at a 5% or greater slope. Make sure all downspouts discharge outside of this graded area. You may find it necessary to install a French Drain around your building’s perimeter in order to keep groundwater from running under your building.

This entry was posted in Constructing a Pole Building, Pole Building How To Guides, Ventilation, Concrete, Building Drainage, Building Interior, Pole Barn Questions, Building Overhangs and tagged , , , , , on by .

Wire Mesh in Slabs on Concrete

Many concrete finishers have switched to synthetic fiber mesh reinforcement for concrete slabs to help reduce surface cracking. In doing so, many of these finishers have completely eliminated traditional welded wire mesh (WWM).

But while fiber mesh has advantages, it also comes with potentially costly drawbacks.

This may sound surprising, given fiber mesh’s big appeal is its time and money savings. By using it, finishers don’t have to pay a premium for WWM, and don’t have to take time to correctly install it. Some concrete finishers actually offer a price break for fiber mesh.

While fiber does reduce surface cracking, it won’t eliminate cracks completely. Worse, when a crack does develop, lack of WWM can be a real weakness.

rebarThis is because properly installed WWM will keep concrete on both sides of a crack from separating further and will keep them on the same plane— preventing differential settling. Fiber mesh won’t.

Repairs to differential settling don’t leave a great impression on new post frame building owners. You have to grind down the surface on either side of the crack, fill the gap with epoxy and try to smooth it all out. Even when done well, this leaves a visible scar.

While such scars are mostly cosmetic, they scream “poor workmanship” to clients, leading many to doubt the slab’s structural integrity. 

As the use of fiber mesh has grown, more and more of these problems have been seen on job sites, however finishers are beginning to take notice. Soon after switching to fiber mesh, one found a dozen cracking and settling slabs at a given time. They reintroduced WWM and these problems virtually disappeared.

Chances of differential settling depends largely on underlying soils. Where soil is sandy and stable, settling is less likely and fiber alone can be a reasonable choice.

However, in areas with clay and other expansive soils, correcting problems caused by elimination of WWM can cost more in the long run than initial cost savings associated with fiber mesh.

In fact, the best way to minimize chances of cracking and settling is to use fiber mesh and WWM together.

Like any structural product, WWM won’t do its job unless it’s installed correctly. Unfortunately, this is not always done.

Proper installation to provide maximum strength requires mesh to be raised off the ground so when concrete sets, it is in the slab’s depth lower third. This means placing WWM on chairs to hold it at the correct height.

It is crucial to ensure WWM be placed on proper height chairs. Otherwise, WWM will not effectively hold the slab together. 

Wire not placed on chairs will not be effective. But in a rush to get jobs done, some crews eliminate chairs and roll WWM directly out over Code required under slab plastic sheeting covering underlying properly compacted fill. And when installers do use chairs, they must take care not to knock WWM off the chairs during pour. If they do, then they need to reset WWM.

Making sure all of this gets done right can be a training and quality assurance challenge for finishers, and avoiding this challenge may be one reason why so many opt for synthetic fiber for these applications.

However, in soils or poorly prepared sites making settling likely, this type of oversight really needs to be a priority.

This entry was posted in Concrete, Pole Barn Planning and tagged , , , , , , , on by .

Aircrete for Post Frame Cladding

Aircrete for Post Frame Cladding

Reader KRISTOPHER in GARDINER writes:

“Can I use pre-cast aircrete panel in lieu of metal siding for the walls and roof?”

Mike the Pole Barn Guru responds:

It may be possible to use aircrete in lieu of steel roofing and siding, however it would need to be strong enough in bending to span from column-to-column on walls and between trusses on a roof. Product weight would need to be accounted for to adequately design supporting members and attachments could become problematic. All of these considerations could result in some significant investment into engineering costs, perhaps making this system unaffordable.

Aircrete is simply concrete with bubbles. Regular concrete we use for our roads, basements, and foundations traditionally is made from Portland cement. This combination hardens into a highly dense material with impressive compressive strength. Addition of iron rebar adds additional structural integrity.

Aircrete reduces or eliminates traditionally used aggregate. Instead of including gravel or other coarse aggregate types, aircrete relies on incorporating premade foam pieces to essentially add bubbles of airspace within a concrete mix. Instead of foam, another option is mixing certain types of reactive substances into a wet cement mix. This chemical reaction creates gas bubbles within a cement and water slurry to harden with empty cavities.

There is no set recipe for aircrete, as exact amounts of foam or air bubbles depend on how aircrete will be used. Generally, aircrete with higher proportions of foam or air bubbles will offer less compressive strength but higher insulation capacities. Builders and homeowners might decide to use some traditional aggregate like gravel in aircrete applications requiring structural strength.

Aircrete offers many traditional concrete benefits with added properties to enhance sustainable and energy-efficient homes. If you have ever been inside an inadequately sealed cement and cinder block home, chances are it felt cold and damp. Aircrete offers superior insulation properties due to foam and air bubbles built into concrete itself.

As with regular concrete, aircrete can be formed into blocks for easy application or poured into forms for walls and other interior and exterior purposes. In one sense, aircrete is similar to ICFs (insulated concrete forms). It increases the insulation capacity of traditional concrete. Unlike ICFs, however, aircrete doesn’t require separate polystyrene foam blocks or other rigid insulation, subsequently connected with space in between for pouring a concrete wall.

Other benefits of aircrete for a sustainable home include:

  • Relatively inexpensive
  • DIY friendly for innovative homeowners and home builders.
  • Good compressive strength
  • Self-leveling
  • Improved acoustic properties

Aircrete is an innovative approach to “greening up” traditional concrete. However, in some cases, use of aircrete can lead to certain disadvantages. When high densities of foam are included, aircrete can become brittle, and chipping can occur. This type of aircrete will have limited compressive strength and could not be load-bearing.

Homeowners should understand aircrete and concrete are fundamentally different construction materials with different uses. Concrete incorporating natural aggregate has different performance characteristics. Concrete is a great alternative wherever high levels of compressive strength are needed. Where increased insulation is a concern; however, aircrete offers superior advantages.

Aircrete drastically improves upon insulation properties of regular concrete. According to one analysis, aircrete might be able to offer R-6 per inch insulation values. Blown cellulose, for comparison’s sake, only offers R-values of 3.7 per inch. A home built with six inch thick aircrete blocks could potentially achieve an R-value of 36.

Aircrete is also water-resistant and fire-resistant. Portland cement in aircrete offers necessary water resistance. Foam or air bubbles provide an added layer of protection against moisture. Like all cement structures, specific vapor barriers can also help reduce condensation penetrating your home. For homes located in areas where wildfires are an increasing threat, aircrete exteriors can diminish vulnerability and increase overall resiliency.

Aircrete is most often used for exterior and interior walls. However, aircrete can also be used for several other home applications, such as precast blocks and panels and concrete slabs for an insulated flooring system. In some cases aircrete is used for poured roofs, increasing insulation capacity of ceilings and attics where heat tends to escape from homes. 

Cost of building with aircrete will depend on several factors, including thickness of application, cost of Portland cement and how much foam aggregate is included. In general, however, aircrete will be much less expensive than building with regular concrete.

This entry was posted in Budget, Insulation, Pole Barn Questions, Pole Barn Planning, Pole Barn Structure, Concrete and tagged , , , , , , , on by .

Floor Plans, Spray Foam for Condensation, and a Sill Issue

Today the Pole Barn Guru answers reader questions about floor plans, adding spray foam to an existing structure for condensation control, and solutions for a sill at 18′ OHD opening.

DEAR POLE BARN GURU: What do you charge to take my floor plan and send me engineered drawings? SHANNON in JONESBOROUGH

DEAR SHANNON: We only furnish engineer sealed plans and verifying calculations with your investment in a new Hansen Pole Building. If you just need professionally done floor plans, please check this out: http://www.hansenpolebuildings.com/post-frame-floor-plans/?fbclid=IwAR2ta5IFSxrltv5eAyBVmg-JUsoPfy9hbWtP86svOTPfG1q5pGmfhA7yd5Q

 

DEAR POLE BARN GURU: Hello! I have recently purchased a pole building that is not insulated & It does not have the vapor barrier/plastic installed between the wood framing and the sheet metal. We would like to insulate this building. We are thinking spray foam because I have heard you can apply it directly to the steel. Do we have any other options for insulating this? Any advice is greatly appreciated. Thank you!! KRYSTA in SPOKANE

DEAR KRYSTA: If it has no sort of condensation control between roof framing and roof steel then two inches of closed cell should be sprayed to underside of roof steel to control condensation. If your roof trusses are designed to support a ceiling, then install one and blow in R-60 fiberglass on top of it, ventilating the dead attic space appropriately.

For your walls, you can use rock wool insulation batts, completely filling wall cavity, with a well-sealed vapor barrier on interior face.

 

DEAR POLE BARN GURU: I need to pour a concrete sill at the 18’ wide entry to my pole shed in South central Wisconsin. The interior of shed is compacted crushed limestone, the apron leading up to it will be asphalt so a concrete sill seems like a good idea to protect asphalt edge. I can’t find any advice online so I hope you can help me out with your expert thoughts. First, good idea? Second, thickness. It would be about 12” wide. The base is 30 years old, thick and well compacted. Any help would be greatly appreciated. Thanks for your time. JAPH in WISCONSIN

DEAR JAPH: My concern would be possible frost heave of a concrete sill. I would probably excavate outside my building so top of asphalt and top of interior compacted crushed limestone were at same grade and call it good. Takes away possible heave of concrete and saves cost of concrete.

 

This entry was posted in Building Interior, Pole Barn Questions, Budget, Pole Barn Design, Pole Building How To Guides, Pole Barn Heating, Pole Barn Planning, Ventilation, Concrete and tagged , , , , , , on by .

Contract Scheduling and Terms

Disclaimer – this and subsequent articles on this subject are not intended to be legal advice, merely an example for discussions between you and your legal advisor.

Please keep in mind, many of these terms are applicable towards post frame building kits and would require edits for cases where a builder is providing erection services or materials and labor.

SCHEDULING: Upon completion of all required documents by Purchaser (including, but not limited to, Instant Invoice, Door locations and Jobsite Delivery Information), Purchaser’s online approval of Seller’s plans, and appropriate payment, shipment(s) will be expedited to be as soon as is practical, however no guaranteed time frame is promised. Purchaser will receive multiple deliveries over a span of a week or more. Seller has little or no control over the exact date of arrival, nor can Purchaser specify any exact date and/or time for deliveries.

Some vendors will require Purchaser or Purchaser’s adult agent to be present at time of delivery. Materials may be delivered via any combination of USPS, UPS, FedEx or freight carrier, the choice of which is strictly determined only by Seller and/or Seller’s vendors. In the event tracking information is furnished to Purchaser, the responsibility to monitor tracking is upon Purchaser.

EXCLUSIONS: Seller is not a contractor, architect or engineer in any state, and both parties agree no such representation has been made. Seller does not and cannot endorse, nor take responsibility for the performance of any contractor or laborer hired by Purchaser, even if the name was provided by Seller. Purchaser waives any and all right of claim against Seller for non-performance of any materials improperly installed by any contractor. 

Seller cannot predict nor guarantee any permit, construction or labor costs. Any and all construction labor and equipment, as well as nails 16d or smaller, staples or tacks which can be commonly driven by pneumatic powered equipment are to be provided by Purchaser or Purchaser’s agents. The need for butyl tape sealants, water seals, closures for wall steel or polycarbonate panels, caulking or any other sealants is to be determined and furnished by Purchaser. 

While great effort is made to include web bracing material Seller does not see final engineered truss drawings prior to shipment so cannot verify, in advance, all web bracing requirements. As such, any materials for web bracing required beyond what is originally shipped with building kit, shall be furnished by Purchaser. Seller also does not furnish, nor pay for, any cement, concrete, pre-mix, rebar, wire mesh or any other materials which would be used to backfill Purchaser’s building columns or to construct any concrete floor, foundation or curb.

Concrete floors and/or continuous footings and/or foundations, electrical, plumbing, HVAC, insulation, drywall, site or grading plans, non-structural interior walls or partitions, provision for flooding, firewalls, sprinklers or other fire separations, gutters and downspouts, energy/heat loss calculations, meeting requirements of any energy code, meeting requirements of The International Wildlife-Urban Interface Code, or materials not provided by Seller, as well as the design of or specifications for any concrete work (including but not limited to driveways, porches, approaches, slabs, retaining walls, footings for walls, continuous foundations or stem walls) are specifically excluded from this Agreement and provided plans and/or calculations to be provided by Seller or third party engineer(s). 

Seller’s plans include a foundation designed as an isolated, shallow foundation with embedded columns. In the event any other foundation type be desired, or required, Purchaser will need to hire an appropriate engineer, at Purchaser’s expense. Any “plot” plans, floor plans or site tests/reports/engineering, or other “special” reports requested by any agency for Purchaser’s building are to be provided by Purchaser. Stairs, lofts, decks, mezzanines, second or higher floors, if included, will have handrails provided by Purchaser, unless otherwise specified. 

Purchaser further agrees to not enter into any other agreement, either verbal or written, with any of Seller’s suppliers, manufacturers, agents, employees or subcontractors, without the express written consent of Seller.

This entry was posted in Trusses, Pole Barn Homes, Post Frame Home, Barndominium, Shouse, Lumber, Pole Barn Design, Lofts, Pole Barn Planning, Skylights, Building Contractor and tagged , , , , , , , , , , , , , , on by .

Question About a Pole Building Under Construction

If you are like me, when you hire a professional to do professional work, you expect them to be experts and to do things correctly. Few things in life upset me more than when a builder gives a client a great price and then cuts corners in order to make a profit.

Facebooker CHRIS in TENNESSEE messaged me:

“Question about our 30×40 pole barn that is being built. Our builder set our 6×6 post straight into the ground without any type of base at the bottom and just back filled the hole with dirt. Our plans from the company show a small concrete area at the bottom of each hole but they did not do that. I wanted to reach out to you to see if you can think of any long term issues I’m going to have down the road. Just looking for some education before talking to the company. Thanks.”

Sigh…..without an adequate footing beneath columns your building is going to sink. A minimum 6″ thick concrete footing needs to be poured under every column. There should also be a provision to prevent uplift. I would recommend no further payments to them until this issue is resolved. They should be providing an engineer certified solution to this.


“They just finished the metal on the building yesterday and it dawned on me I never noticed them putting concrete in the holes. We have a security camera on the corner of the house so I pulled up the video footage and they went straight from the holes being drilled to dropping the post in. Can that even be fixed that they are this far in the build?”

It can be fixed, but it is going to take a lot of work on their part. At this point, any repair should be done only with involvement of a Registered Professional Engineer to design a fix, supply sealed drawings and to sign off on completed work as being adequate. Most important part of your building is its foundation – this is not a place to compromise. Do not get bullied into backing down, you have paid for a good building and should expect to receive one.

“I’ve been confused about how the post should be set after trying to search the Facebook group. I saw people say never use concrete that it will rot the post and cookies are useless.”

There is a lot of bad information out there and a lot of armchair engineers (including builders). Concrete does not contribute to decay of properly pressure preservative treated wood. In most cases cookies are inadequate in both thickness and diameter.

“I just got off the phone with my builder (******** Barn Company) and of course they said they build 100’s of buildings like this and don’t have an issue.”

It doesn’t matter if they have built a million this way. Unless they are willing to provide an engineer sealed drawing (specifically for your building) to confirm it is adequate – call b.s.

You are likely going to get a lot of pushback from them, as they have screwed up and this fix is going to cost them money.

“My drawings show the concrete at the base and I questioned that and I got some story that “Oh, that’s in our software by default and cannot be remove on our plans.””

8 x 12 would not have been adequate anyhow. Again – if what they have done can be verified by an engineer, then okay – reality is it cannot.

Be prepared to have to hire a Construction Attorney and whatever you do, under no circumstances pay them anything more unless this condition is resolved, or your attorney tells you it is okay to pay.

“Thank you for all the professional advice.”

This entry was posted in Concrete Cookie, Footings, Pole Barn Questions, Barndominium, Constructing a Pole Building, Shouse, Building Contractor, Concrete and tagged , , , , on by .

Cement Versus Concrete

Cement versus Concrete

Scraping a chalkboard (also known as a blackboard) with fingernails produces a sound and feeling most people find extremely irritating. Basis of this innate reaction to sound has been studied in the field of psychoacoustics (branch of psychology concerned with perception of sound and its physiological effects).

mr owl tootsie roll popIn response to audio stimuli, a human mind’s way of interpreting sound can be translated through a regulatory process called Reticular Activating System. Located in the brain stem, the Reticular Activating System continually listens, even throughout delta-wave sleep, to determine importance of sounds in relation to waking cortex or rest of body from sleep. Chalkboard scraping, or noises illiciting an emotional response, have been known to trigger tendencies from the fight or flight response acting as the bodys primary self-defense mechanism.

Superman has his Kryptonite, mine happens to be misused construction terms. Here, in Middle America, I have gradually adapted to term “rafters” being used for roof trusses. My favorite chalkboard scrape happens to be with use of “cement” when the correct term would be “concrete”.

Although terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is a mixture of aggregates and paste. Aggregates are sand and gravel or crushed stone; paste is water and portland cement.

Cement comprises from 10 to 15 percent of concrete mix, by volume. Through a process called hydration, cement and water harden and bind aggregates into a rocklike mass. This hardening process continues for years meaning concrete gets stronger as it gets older.

Portland cement isn’t a brand name, but a generic term for a cement type used in virtually all concrete, just as stainless is a type of steel and sterling a type of silver. Therefore, there is no such thing as a cement sidewalk, or a cement mixer; proper terms are concrete sidewalk and concrete mixer. I rest my case.

 

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Column Hairpins, Going Bigger, and Cutting Corners

Today the Pole Barn Guru discusses Rebar hairpins, a bigger build, and cutting corners on the construction process.

DEAR POLE BARN GURU: Hello, regarding the column to concrete hairpins. I’ve talked to a couple different contractors and they both have cringed when I discussed tying the pad to the columns. They say around here everyone uses a floating pad to avoid concrete cracking. Is there another option to meet the design requirement? Thanks, HANS in PLYMOUTH

DEAR HANS: If the contractors are cringing from hairpins it is from one or more of the following reasons:

a) They have not placed the bottom of the hole below the frost line,
b) They have not adequately placed a concrete collar around the base of the column,
c) The site has not been adequately prepared to minimize ground water below the slab,
d) The site has not been properly prepared to accept the concrete slab.

In order to meet the design requirements of the engineer of record, the hairpins are a necessity.

P.S. Every slab is going to crack, it is properly controlling the cracks which makes for a good pour. By using zip strips, expansion joints or saw cuts no more than every 12 feet for a nominal four inch thick floor, cracking can be localized to these points.

DEAR POLE BARN GURU: As I was warned, my barn has proven to be too small. Can I order an extension or a second building and just extend my current 30×32 Hansen pole barn an additional 20 feet? Thanks TJ in SPOTSYLVANIA

DEAR TJ: I know this is difficult to believe, but you are the first person to ever have this problem. No, not really, it is a common occurrence and I have been guilty of it personally. Whatever one constructs, it seems the possessions increase to fill the available space plus 10%.

We can have designed for you an addition to increase your building length. Your Hansen Pole Buildings’ Designer will be in contact with you before the weekend.

DEAR POLE BARN GURU: My builder did not use the tape to seam my insulation. Short of removing the entire roof, can I tape seams from bottom and be ok? Is the taped seams purpose to stop heat and cold air from clashing to create moisture or is it to catch moisture that is going to accumulate no matter what?

2nd question. The book or plans said for the ridge cap to use 1/4 screws. We do not have any and they would be too short anyways because of the foam that goes under the ridge cap. What is the proper size screw to use. TALMADGE in WARRIOR

DEAR TALMADGE: It is aggravating when builders are in such a hurry they neglect to do simple thing such as using the adhesive, which is on the reflective radiant barrier tab already, to seal the barrier seams. All it would have taken was to peel off the pull strip! You can tape the seams from the bottom, which is going to be a lot of work and which your builder should offer to do for you at no charge. In order for the reflective radiant barrier to function properly, it needs to create an air tight barrier between warm moist air inside of your building and the cooler roof steel.

1-1/4 inch long stitch screws were furnished to attach the ridge cap, as well as corner and rake trims. They should be plenty long enough.

 

 

 

This entry was posted in Footings, Insulation, Pole Barn Questions, Pole Barn Design, Steel Roofing & Siding and tagged , , , , , on by .

A Door Guide with a Roller, When to Pour Concrete, and Bedrock Anchors!

DEAR POLE BARN GURU: I am looking for a bottom guide for a sliding barn door. I was hoping to get a guide with a roller vs. just a roller. I noticed some guides trap the roller in a channel on the bottom of the door. I would like to know if you have that and where to purchase in Lower west Michigan.

Thanks, GERARD in PLAINWELL

DEAR GERARD: I have found the very best sliding door guide systems do not use bottom rollers at all. Known as “stay rollers” the bottom rollers tend to be problematic, especially in tough climates or when large animals are present.

Figure 27-6

The most secure and effective method utilizes a bottom girt for the door which is most typically a galvanized steel channel 1-1/2” x 3-1/2” (think of a steel stud) with a slot in the 1-1/2” face towards the ground. A galvanized steel “L” is mounted via brackets to the wall in the direction the door slides open. The upward leg of the L engages with the slot in the bottom of the lowest sliding door girt.

This design solution provides stability for the bottom of the door, preventing it from coming away from the building, or slapping against the ribs of the steel as it opens. Hansen Pole Buildings does not provide sliding door components other than with the investment into a complete post frame building package. You might try the ProDesk at your local The Home Depot®, as they should be able to order the parts in without you having to pay an onerous amount of freight.

 

DEAR POLE BARN GURU: Would I have the concrete slab poured before the building is erected or pour the slab after the poles are installed? Thanks. JOHN in REMER

DEAR JOHN: One of the beauties of post frame construction is the ability to be able to pour your new building’s concrete slab on grade at any time after the columns are placed in the ground. My personal preference is to at least wait until the roof is on – as it provides greater protection from sudden unexpected rainstorms as well as sun. The best time to pour (in most situations) is after the building shell is fully completed. Premix concrete trucks do seem to have an affinity for running into building columns which are not part of a wall.

 

DEAR POLE BARN GURU: Dealing with a site that is less than 20 inches above bedrock and is a wet environment. Frost line construction standards normally require 48 inch depth. What foundation, site prep concerns are relevant. Hoping for a barn about 30 x 40 x 12 RON in ONTARIO

Footing DetailDEAR RON: Code specifies the depth of foundations (in this case your columns) must be either below the frost line, or to solid bedrock. You will want to discuss your particular site challenges with the registered design professional (RDP – architect or engineer) who provides the sealed plans for your building. Our engineers will often solve this anchorage problem by having you drill holes into the bedrock to epoxy in rebar pins which will be embedded into the columns, then backfilling the holes with concrete. To minimize potential frost heave issues, you will want to read my articles on site preparation (use the search bar at the upper right of this page) – as you will want to remove any soils which could contribute to heaving.

 

This entry was posted in Concrete, Footings, Uncategorized, Pole Building Doors and tagged , , , , on by .

Fall Up, Go Boom

Fall Up, Go Boom

What? Sir Isaac Newton pretty much confirmed things do not fall up.

Well, this building did not actually “fall” up – it was sucked out of the ground. How would I know this? Look at the ends of the columns which are lying on the ground. There is no concrete attached to the bottom of the columns, nor is any method for preventing uplift even obvious to the more than casual observer.

 

In review of the NFBA (National Frame Building Association) Post-Frame Building Design Manual (January 2015) the issue of column uplift is all but ignored. Beginning with the end of Page 5-37, it is concluded two pages later. Options for preventing uplift are really not addressed.

For decades we, if not many other post frame designers and builders, have relied upon the bond strength between concrete and wood in designing column embedment to prevent uplift issues. More can be read about concrete to wood bond strength here: https://www.hansenpolebuildings.com/2013/04/pole-barn-post-in-concrete/.

I’ve expounded previously upon the use of nail on truss plates for assisting in uplift construction (https://www.hansenpolebuildings.com/2013/04/truss-plates-for-column-uplift/).

There truly is very little information available. Of all places, I did find some relevant information on the City of Hendersonville, Tennessee website (www.hvilletn.org):

“Column uplift protection: Columns shall have uplift protection by one of the following methods:

1. Two 2x6x12 inch column uplift protection blocks attached to each side of the base of the column. The column uplift protection blocks must be placed horizontally, attached per Table 5 and comply with Section R317.

2. 12 inch high, concrete collar poured on top of footing around the post, with 2- #5×9 inch rebar placed through the post at 3 inches and 9 inches from bottom of post in opposite directions. The rebar ends shall be installed in accordance with ACI 332 for the specified distance in inches from contact with the soil.”

Table 5 mentioned above happens to be five 16d hot dipped galvanized nails into each block.

While I was researching for this article, I happened upon an example for preventing uplift in an all steel building. The building in this case was a 60 foot span and steel frames every 25 feet. In this case the design footing was eight feet square by 3’8” in depth!!

The all steel building is going to have footings which take nearly nine yards of concrete per bearing location!! This is near the capacity of a pre-mix concrete truck, per one end of each frame!

Getting back to the post frame building design solution, our engineers have determined reliance upon the concrete to wood bond strength only is not quite as conservative as they might like.

The solution – Hansen Pole Buildings, LLC engineered post frame buildings now have added the nail on uplift plate tot the roof supporting columns to tie into the concrete column encasement.

The investment is minimal and it does afford some added insurance of success in preventing uplift.

This entry was posted in Pole Barn Design, Pole Barn Structure, Columns and tagged , , , , on by .

R-50 Insulation?

DEAR POLE BARN GURU: Did I read on this web page that there is a installation product that is one inch thick with a R rating of R-50? DELLA in DALLAS

DEAR DELLA: Unless I am mistaken, I believe your question is about insulation, rather than installation.

Yes, there is such a product. Here is the link to the article: https://www.hansenpolebuildings.com/2016/11/one-inch-insulation-r-50/

My guess is it may be on the expensive side, but if it works, it could be quite the trick. I am in the process now of getting a quote with the idea of using it between the framing and steel when I reroof my house near Spokane, Washington.

DEAR POLE BARN GURU: What should I pay for metal roofing labor costs? JUSTIN in GARLAND

DEAR JUSTIN: In the case of most structural construction on low rise buildings, the cost of labor is typically equal to about 1/2 of the cost of the materials. Obviously steep slopes, multiple hips and valleys, pitch changes (basically more complex roofs) will add to the cost.

DEAR POLE BARN GURU: The detail for setting posts shows 8” concrete under the posts and up 18” on the posts.

Can we pour the bottom 8” of concrete in the caissons, let it set overnight and then set the posts on

the 8” and pour the 18” of concrete ? One of the videos shows doing it this way. JIM in WINDSOR

DEAR JIM: While I am unaware of any video Hansen Pole Buildings has produced which shows a two stage pour, it can certainly be done. I usually try to avoid it just for the fact I am frugal and do not like to pay the short haul charges from the premix company. By pouring it all at one time, you can also speed up the construction process by a day, as you will not be waiting for two sets of concrete cures.

This entry was posted in Roofing Materials, Steel Roofing & Siding, Concrete, Footings and tagged , , , on by .

Concrete Considerations from the PBG!

DEAR POLE BARN GURU: Is concrete included in price? TRACEY in SUMTER

DEAR TRACEY: No, we do not include concrete in the price and here is why:

Most familiar, as well as most available is the Sakrete® general purpose High Strength Concrete Mix. When mixed per the manufacturer’s instructions, this mix affords a compressive strength of 4,000 psi (pounds per square inch) at 28 days.

The instructions are: Empty the contents into a mortar box, wheelbarrow, or mechanical mixer. When mixing by hand, form a crater for adding water.  Add water a little at a time.  Avoid a soupy mix.  Excess water reduces strength and durability and can cause cracking. A 60 lb. bag should be mixed with three quarts of water, an 80 lb. bag four quarts.

Now the realities of using bagged concrete for post frame building footings….

treated postIt is not unusual to have concrete encasements of 24 inches or larger in diameter and 18 inches or more in depth, in order to prevent building settling and uplift issues. One hole this size would take 4.71 cubic feet, or about 700 lbs. of concrete! Even a very small building with 18 inches of diameter and depth takes 2.65 cubic feet or about 400 lbs. of concrete.

With either 60 or 80 lb. bags, it is going to take a lot of bags! An average building could easily have 20 posts, and if looking at 700 lbs. of concrete per post, we are talking about 7 TONS of concrete (3-1/2 yards).

Ignoring the huge number of bags involved, there are some other realities.

Ever looked at the pallets of readi-mix bags at the lumberyard? Take a peek, next time. Notice how many of them are broken or leaking.

Due to weight, it may very well mean another delivery and another delivery charge. Trucks do not run for free.

Bags can (and will) break when being handled during delivery, unloading and being moved around the jobsite. It is going to happen, just plan on it.

From experience, lots of projects are not begun immediately after delivery. It is not unusual for delays of weeks, or even months before actual construction begins. Improperly stored, bags can get wet or absorb moisture and become solid before time for use. This equals a total waste of money, other than the chunks of concrete make for solid backfill.

Then there are the builders who insist upon throwing the entire bag (usually including the bag) into the hole. Their idea is ground water will cause the readi-mix to harden. Why does this not resemble the manufacturer’s instructions?

Readi-mix must be mixed thoroughly and evenly. How does mixing over 200- 60 lb. bags of Sackrete® by hand sound? Add too much water (three quarts exactly per 60 lb. sack) and the strength is reduced.

Use too much? As holes are always perfectly round (not), it is going to happen.

Save time, effort and money. Often all three can be saved by having the local pre-mix concrete company deliver concrete for holes (even if a “short load” fee is charged), as opposed to mixing on site.

DEAR POLE BARN GURU: I am building a 36 x 40 pole barn and I’m on a grade that drops approximately 4′ over the span of the building footprint. A home builder friend, a structural engineer, and my concrete guy have recommended traditional foundation with wet set permacolumns, but the builder I’ve contracted with wants to set columns on footers 3′ to 5′ in the ground and not use the permacolumns. The pole barn builder doesn’t think I need a retaining wall and should just have an excavator level what i need with a slope off the back. Seems a retaining wall in the back is better, which my concrete guy will pour, but still recommends foundation to eliminate frost heave. Use for building is car storage and shop with a lift.
Thank you in advance for your time and help. CHRIS in ST. LOUIS

DEAR CHRIS: This reminds me of a joke I once heard – a home builder friend, a structural engineer and a concrete guy enter a bar…….

Oops, kind of off track!

Some of the answer is going to depend upon what you want your yard to look like.

In any case – the actual pad of the building is going to need to be properly compacted (emphasis on proper) so those costs will be fairly even in any case. You’ll want to be reading about proper site preparation and compaction here (it is lengthy): https://www.hansenpolebuildings.com/2011/11/site-preparation/

What might appear to be the least expensive would be to just order columns long enough to get the required embedment depth as shown on the engineered plans, then fill afterwards, sloping away from the building. In order to keep the fill from sloughing off, it will probably result in a slope next to your building which will stretch out as far as 20 feet. You could easily invest in several hundred yards of fill!! If you can live with the look, might be the answer.

Building on top of a foundation – this is going to be the most expensive and certainly not the choice I would probably be making. It is also going to be tougher to build upon, due to the height of the walls plus the foundation.

Which leaves – build a retaining wall. I like this idea. Columns do not have to be longer (as long as fill is properly compacted).

By the way – there is no reason for ANY of these versions to frost heave as long as the site has been properly prepared. Read more about how to avoid frost heave issues here: https://www.hansenpolebuildings.com/2011/10/preventing_frost_heaves_in_pole_building_construction/

DEAR POLE BARN GURU: How much is the drip stop application for labor/material? Usually it comes already attached to the metal paneling. Do you figure it by square feet? JOSH in MANKATO

DEAR JOSH: For materials you are going to be looking somewhere in the neighborhood of 53 cents per square foot of roof surface. As a builder, if you are anywhere it is typically windy, I am going to give you a decent discount on my labor for having invested in it, because I don’t have to fight rolls of insulation flapping in the breeze.

 

This entry was posted in Pole Barn Design, Roofing Materials, Pole Building How To Guides, Concrete, Footings, Building Drainage, Columns, Insulation and tagged , , , , , , on by .

Cost Savings of a Crawlspace vs a Slab!

DEAR POLE BARN GURU: I am building a pole barn 50 foot clear span wide, and 70 foot long, 16 foot to the eve. I am using 4×4 metal uprights on 20 foot spans, red iron purlins and stringers, and 4×4 metal welded all around the top. I am using conventional wood trusses engineered for my area on four foot centers. My question: Are the 4×4 square tubing uprights on 20 foot centers, with welded 4×4 square tubing around the top for the top plate heavy enough for this large of a building? Thanks, FLOYD in KIM

DEAR FLOYD: You asked for my honest opinion – here it is. I wouldn’t stand under or near your building as proposed in a wind or snow storm. With a 30 psf (pounds per square foot) roof snow load and a 100 mph design wind speed under the 2009 IBC (International Building Code) you are talking about some significant loads to be dealt with.

My best recommendation is to spend the money to have your proposed design reviewed by a RDP (registered design professional – engineer or architect) who can make the necessary revisions so you can end up with a building which will actually stand up under the imposed loads.

 

DEAR POLE BARN GURU: Read the article on crawl space verses slab. Is there any pictorial drawing showing a pole barn construction with a crawl space so I can better understand the pole installation? I assume it’s the same as ground level for a slab, but only 4” lower for the crawl space. Still would like to visually see drawing to fully understand. It is my plan to do most of the construction, but one thing I won’t do is concrete work and the price of concrete installed is expensive. At least a wood sub-floor I can handle, not to mention it makes it easier to run electrical, ducting and piping. DOUG in KIOWA

DEAR DOUG: I am with you when it comes to concrete work – I just won’t go there if I can at all help it!

imagesCrawl spaces for post frame buildings are most normally elevated above grade. The IBC (International Building Code) requires any not pressure preservative treated beams in a crawl space to be at least 12 inches above the underlying soil, and joists to be 18 inches above.

Think of the raised wood floor being created as a “loft” floor, with the beams attached to the columns and joists running between the beams. The difference being this loft floor is usually going to be somewhere 18 to 36 inches above grade (most people prefer their crawl spaces to be tall enough to actually allow easy access for running utilities).

 

DEAR POLE BARN GURU: How much for 12 x trusses that are 24′ with 4/12 or 6/12 pitch? Thank you DUNCAN in JOHNSTOWN

DEAR DUNCAN: Although we are not manufacturers or resellers of just trusses, I can give you some guidance as to information which will be needed in order for you to get a correct price.

The easiest thing will be to get a copy of your engineered building plans into the hands of the local truss providers. The plans will have the information required to give you an accurate price for the trusses, as well as insuring they will be designed to meet the loading conditions necessary for your particular building, at your site.

These items will include jobsite address, Roof Exposure Factor (to the wind, also known as Ce), the ground snow load (Pg), the sloped roof factor (Cs), the thermal factor (Ct) as well as the Importance factor (I). The type of roof materials being used as well as if there is a ceiling or not will also play into the end truss design. If your local Building Department has a minimum roof snow load requirement, this needs to be passed along as well.

With all of the above in hand, the truss designer can plug the variables into the computer program which does truss design and derive a price for your truss package.

The above is merely a broad overview, to delve deeper, it would behoove you to read the article I penned for Structural Building Components magazine: https://www.hansenpolebuildings.com/mike-the-pole-barn-guru-profile/it-isnt-your-grandpas-barn/

 

 

This entry was posted in Building Styles and Designs, Roofing Materials, Trusses, Footings, Budget and tagged , , , on by .

Hurl Your…Concrete Cookies

I know none of us has ever experienced this condition, but we all know of someone who has had the hurling issue, often after a period of personal discussion with some of the friends of George Thorogood.

In this instance, I’m not thinking either of the example above, or the tasty oatmeal raisin cookies my grandma made for us when we were kids. I am making specific reference to the pre-cast chunks of concrete usually four to six inches in thickness and 12 to 18 inches in diameter which are sold or provided for footings in pole buildings.

The basic concept is to throw concrete cookies in the bottom of the augered holes and place the building columns directly upon them. The general idea is for the cookies to support the weight of the building, to prevent settling.

My recommendation – RUN, DO NOT WALK, away from this as a design solution.

Why?

They are a failure looking for a place to happen.

Let’s look at what a footing is supposed to do. The dead weight of the building PLUS all imposed live loads must be distributed to the soils beneath the building. Sounds pretty simple, eh?

Concrete Cookie

Concrete Cookie

To begin with, the International Building Codes require concrete footings to be a minimum of six inches in thickness. This eliminates immediately any concrete cookies which are less than this thickness (most of them).

Examine a fairly small example – a 30’ wide building with columns spaced every eight feet. The actual weight of the building (dead load) will vary greatly depending upon the materials used. Steel roofing and siding will be lighter than shingles and wood sidings. For the sake of this example, we will use a fairly light 10 psf (pounds per square foot) building weight. The Code specifies a minimum roof live load of 20 psf. This means each footing must carry the weight of one-half of the width (15 feet) times the column spacing (8 feet) times 30 psf. Doing the math, 3600 pounds.

In many parts of the country soil bearing pressures are as little as 1500 or even 1000 psf. Basically – the easier it is to dig, the lower the capacity of the soil to support a vertical load.

For every foot of depth below grade, the soil capacity is increased by 20%. Other than with 1000 psf soils, for every foot of width over one foot, the capacity also gets a 20% increase.

With 1500 psf soil, and the bottom of the footing four feet below grade, a 12 inch footing will support 2700 pounds per square foot.

A 12 inch diameter footing covers 0.785 square feet, a 16 inch 1.4, 18 inch 1.77, 24 inch 3.14.

The 16 inch footing would support exactly the 3600 pounds from the example above. However – lots of places in the country have snow loads (which the footings must support) and many buildings are wider than 30 feet, or have columns placed over eight feet apart.

Trying a 40 foot span, with a 40 psf roof snow load, same eight foot column spacing, would mean resisting an 8000 pound load! With 1500 psf soils, even a two foot diameter footing would be inadequate.

In most cases, the use of concrete cookies as footing pads proves to be both inadequate and a waste of good money. To insure a building won’t settle, (from inadequate footings), look for a plan produced by a registered design professional who is proficient in post frame building design. He/She will have the history and training to design your building to withstand the loads…which begins with the foundation.

This entry was posted in Constructing a Pole Building, Pole Barn Structure, Concrete, Concrete Cookie, Footings and tagged , , , , , on by .
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