Tag Archives: bedrock

Site Prep, Brackets on Slab, and Treated Lumber

This Wednesday the Pole Barn Guru answers reader questions about site preparation and underground obstructions, a recommendation for building with wet set brackets on slab, and whether or not Hansen Buildings uses lumber treated for in-ground use– UC-4B.

DEAR POLE BARN GURU: We recently started the ground work for our future 48×72 pole building. Half way through excavation the crew hit a solid slab of rock at the corner of our building site. It appears to be Pennsylvania blue stone and the space that it takes up includes a majority of the back and left side where the building walls would sit. We were able to achieve a level pad but we are extremely concerned that now we won’t be able to build on this site. This is the only place on our property that has room for this build and we are very worried that we won’t be able to set poles in the ground do to the size of this solid slab. What are our options, if any? KIMBERLY in PENNSYLVANIA

DEAR KIMBERLY: This brought back childhood memories of my Dad taking me out on a Saturday to a site above Hayden Lake, Idaho where he and my uncles were going to be framing a custom home. Site had been cleared, and there were all sorts of roughly inch and one-half diameter holes drilled into solid rock – they had to blast in order to get a foundation in!

You do have many options, however blasting can be (I have found) quite affordable. Many years ago we built a horse stall barn near Benton City, Washington. This building had a total of 84 columns and was on a rock shelf. Powder monkey came out and blasted all of them for a couple of hundred dollar bills!

There are other choices – you can rent a “ram hoe” attachment for a skid steer or backhoe (this would probably be my pick). Read more here: https://www.hansenpolebuildings.com/2016/12/attacking-pole-barn-rocks-holes/

Or, a jackhammer – I would not suggest this option for more than just a hole or two.

 

DEAR POLE BARN GURU: I am in the planning stages for a pole barn build. The building will be 50 ft wide by 40 ft deep by 16 ft high at the eaves, posts spaced at 10 ft centers. This will go on a concrete pad and I am looking into using Sturdi-Wall Plus wet set brackets. My question is in regard to the height of the posts (roughly 16 ft) and the bending moment loads (wind loads) on the side of the building. Have you designed/installed posts with this height or higher before? If so, is there a place where I can point the planning officials to that shows the calcs and what not so they can make a decision as to whether or not this type of application with my situation will work or not?

I appreciate your help! MICHAEL in UPTON

DEAR MICHAEL: Thank you for reaching out to us. We have provided fully engineered post frame buildings using these very same brackets and eave heights of 24′. Your real solution is to have your building plans done by a Registered Professional Engineer who can provide verifying calculations for all components and connections.

 

DEAR POLE BARN GURU: I have a question about the structure of your pole barns. Do you use treated lumber or non treatmented lumber? I am asking about the post that go in the ground AND the boards that touch the metal roof. I worry about the wood rotting or bugs getting in it. KRISTEN in BAY MINETTE

DEAR KRISTEN: Any roof supporting structural columns are pressure preservative treated to UC-4B per International Building Code requirements. This is a greater level of pressure treatment than you can usually find at big box stores or local lumberyards. Any other lumber used in ground contact will be treated to UC-4A and tags will reflect ‘ground contact’. Lumber in contact with steel roofing (roof purlins) are not exposed to the weather, would not typically be pressure preservative treated. We do always recommend a condensation control be used between roof steel and roof framing. The easiest, from an application standpoint, would be a factory applied to roof steel Integral Condensation Control (DripStop or CondenStop). Other alternatives would be a Radiant Reflective Barrier (we can provide this in six foot width rolls with an adhesive pull strip attached for ease of joining rolls together) or to use two inches of closed cell spray foam.

 

Planning a Post Frame Building Upon Sandstone

Planning a Post Frame Building Upon Sandstone

Reader GEORGE in FARMINGTON writes:

“Mike, in the early stages of planning a pole barn 32’x48’x12′ on a newly acquired piece of property. We’ve cleared the land and found the area we want to erect the building is 100% sandstone. Everywhere we’d have to drill for poles is sandstone as the ground in-between so the sandstone would be the base for the slab as well. Drills real easy but I’m getting conflicting stories from concrete contractors regarding the slab. One says we should “de-couple” the pad from the sandstone by spreading a layer of crushed stone between the sandstone and the slab while another says we should drill into the sandstone and epoxy rebar verticals into it then tie that rebar into the slab rebar. Really don’t know how to proceed as both of these guys appear to be authoritative in their opinions. The de-couple guy claims the sandstone could “heave” the slab up and crack it whereas the other guy says by epoxying vertical rebar to the horizontal rebar, we’ll avoid any issues. Help!” 

Mike the Pole Barn Guru responds:

Thank you for reaching out to me. I have never before been faced with building upon sandstone, so I will give you a logical answer and then advice as to what I would do personally.

In regards to our “de-couple” guy’s advice, if the sandstone would heave your slab up on its own, placing a layer of crushed stone between sandstone and slab seemingly would not prevent slab movement in a “heave event”. Rock types such as bedrock, limestone, sandstone, shale and hard chalk have high bearing capacities. These are very strong and good for supporting foundations because of their stability and depth. As long as sandstone is level your slab will be well supported. My question to him would be more of, “What could possibly cause such a heave event?”

From my research, it appears concrete adheres well to sandstone as long as lime is not added to concrete mixture. This seemingly precludes epoxying rebar verticals into it to tie them together.

Now – what I would do. I would search out a Geotechnical Engineer in your area and broach this situation to him or her. This way you get an expert opinion and it should be a reasonably priced solution.

Where to Stop Metal, Installing a Sliding Door, and Footings

This week’s Pole Barn Guru answers reader questions about where to stop metal in relation to concrete, installing a sliding door to a repurposed building, and the proper depth of footings.

DEAR POLE BARN GURU: Where do I stop my metal in relation to my grade board/ bottom stringer. I’ve set the bottom of my lowest stringer to be the top of my concrete. Does the dirt on the outside end at the bottom of said stringer because I would think moisture would penetrate. Thanks for your time and I enjoy your information. SAM in LANCASTER

DEAR SAM: Bottom of your pressure treated splash plank (lowest stringer) should be 3-1/2″ below top of your concrete slab.

DEAR POLE BARN GURU: I’m putting up a pole barn on the cheap with mostly repurposed materials. I’ve searched the interweb and find no instructions on sliding door track installation. I’m ready to start putting up the siding-do I need to prep/install the track/flashing/guides/stops etc. now or can I side the structure and do all this later? I have yet to buy any track/rollers/hardware, the doors will be 18′ tall and 10′ wide (high clearance for a stack wagon). Any help/guidance/direction would be greatly appreciated. Thanks, DAVE in ELIZABETH

Figure 27-5

DEAR DAVE: You will want to invest in your track and hardware so you have installation instructions including height of track board. Please do not try to wood frame door itself, invest in a steel frame – it will be far lighter in weight and will not warp and twist like a wood frame will.

Normally you will have a 2×6 #2 track board mounted on sliding door header face across your door opening and in adjacent area door will slide over. Top of track board is usually 10″ taller (above bottom of pressure treated splash plank) than door height. Before you run any siding install header, track boards and jambs. Install 1-1/2″ x 5-1/2″ L trim to cover track board. Hang track and track cover trim. Install J Channel horizontally on solid wall below track board and vertically on solid wall side of each door jamb.

DEAR POLE BARN GURU: Hello I called the number on your website and I was asked to send this question to this email address:

I’m considering building a pole barn however am concerned because about 30% of the vertical posts would be on a rock ledge at an elevation above the frost line.

I see the section on your website ‘sturdy wall plus concrete brackets’ not sure if that would apply here and/or what type of bracket or detail could be used in the situation?

Thank you! MARK in WEST MILLFORD

 

DEAR MARK: Building Codes require footings to extend to either below frost line or to solid bedrock. Our third party engineers have worked with similar situations previously and usually come up with a design solution involving “pinning” columns to underlying rock.  We would supply you with a column layout and have you indicate how deep you can get at each column location. A steel concrete stake and a sledge hammer are perfect for being able to do this in advance of your plans being completed.

 

 

Working With a Building Official for Footing Design

Working With a Building Official for footing designs

Long time readers have read me opine on how Building Officials are our friends: https://www.hansenpolebuildings.com/2012/04/i-like-building-officials/

One of our clients recently received this email from his Building Official and shared it with me (red added by me):

“The Town of xxxx stopped plan review on your project because pole buildings with the type of foundation that was called out on your plans have a track record of failing in a short period of time in this area and the soil conditions that exist at your location won’t allow piers to be dug as called out in the plans The ground is full of rock. It was our intent to not have you try and build something that was not going to work and cost you a lot of money. With a frost depth of only 18” “T” foundations are the acceptable method of construction in that area and should be a lot less expensive.”

I responded asking for more explanation of wording in red, and heard back:

We have a few pole barns in xxxx that are much larger in size and in areas that will allow piers to be dug without interference of large rocks below grade. The pier design that they used allows the wood post to sit on a gravel base so any water that might drain down along the side of post after the wood shrinks from age is allowed to drain away.

They also pour concrete up to 3” above the top of the pier and slope the concrete away from the post. Your design traps water at the bottom of post and allows the water to be wicked up by the end grain of the post and promote rot. Although the building codes does allow treated wood foundations to be buried we strongly discourage the use in our jurisdiction.

Thanks for your understanding.”

Thank you very much for your timely response. 

 

I am probably remiss in not having offered a better introduction of myself. I studied architecture at the University of Idaho and have been Technical Director at Hansen Pole Buildings since 2002. I joined ASAE (now ASABE) and ICBO in the mid-1980s. The IBC references ASABE work for post frame buildings which was produced by the structural committee of which I was a member of. I am a frequent contributor as a writer for publications such as Structural Building Components, Frame Building News and Rural Builder magazines. I have also reached out to you on Linkedin, should you wish to know more about me.

We are currently working with Mr. Bxxx on a design solution to incorporate a continuous footing/foundation or thickened edge slab with bracket mounted columns. We and our engineer had not been advised by Mr. Bxxxr as to the soils/rock conditions at his site until quite late in the game. It is my expectation, with Mr. Bxxx’s continued assistance, to have an acceptable design solution arrived at shortly.

While an embedded column pier design on a gravel base sounds wonderful, Code does require a concrete or otherwise approved footing below isolated columns in order to properly distribute weight of building and applied loads. Actual testing of pressure preservative treated columns for over 60 years has proven there to be no decay of properly waterborne pressure preservative treated wood even in the most severe climates (this testing is ongoing in Mississippi). UC-4B rated pressure preservative treated wood is rated for structural use in fresh water, so a column being wet would not increase its chances of decay. In order for decay to occur there must also be oxygen, which is only present in the upper few inches of soils.

Please feel free to contact me with any questions or concerns regarding any post frame building structure. I would also invite you to subscribe to my blog, where there are currently over 1800 searchable articles regarding post frame construction.

“Thank you for your comments. The failures we have seen may have quite well been from pour constructions procedures done 10 to 15 years ago. No way to tell. 

I will look into your articles and may have to change our policies”

Building Officials are not our adversaries and provided with accurate data policies can be crafted to create a winning solution for all parties involved!

Some Pole Barns Deserve a Proper Burial

Some Pole Barns Deserve a Proper Burial

Reader STEPHAN in OGDENSBURG writes:

“Dear Pole Barn Guru,

I have a 30ish year old 32 by 54 feet horse pole barn where half the poles heaved some for more than 1 foot over the years. I need to fix it this year because I am afraid that the strain will make the structure collapse. The code in my area says that post must be buried 5 feet because of frost.

The issue is that the bedrock is between 3.5 and 5 feet below grade. I have an 8 foot wide concrete pad/runway in the middle of the barn (the whole length of the barn). I would like to do it right to last many years.

I considered these different options:

– replacing each posts with sonotubes with bigfoot at the bottom sitting on the bedrock (a lot of work if done with bags of concrete because I would have to do them a few at a time to keep the integrity of the structure)


– replacing bottom of each post with footing sitting on the bedrock and permacolumns (a little less work because the volume of concrete is just a little less)

– pouring a “bond beam” or a full slab on the inside against the posts with thicker sides to support the structure (as per engineer) and then building walls on the inside with 2×6’s to support the roof, and then removing the posts ( I will be losing about 6″ all around because the new walls will be inside the existing shell). I like this idea because I could prepare the area over the winter and get it poured in the spring. My issue is what would I do with the existing slab in the middle of the barn? Should I attach it with rebar and epoxy, pour over or remove the existing slab?
If I go with the last option, what would I use to support the lean-to? If the slab does not have a full foundation that would mean that it is “floating”, should the posts supporting the extension also be “floating” to ensure that they move together?

Or do you have a better option to suggest?

I have attached pictures to show how bad it is. You can see how crooked the ends are by the siding angle and the window in the lean-to area. Thank you for your help.”

Mike the Pole Barn Guru responds:

I am not one to pull any punches – I’ll give my honest opinion, even when I don’t feel it is one you want to hear.

There comes a time when reality sets in….in your pole barn’s case reality will be it needs to be knocked flat, bulldozed into a big hole, lit afire and then replaced. Otherwise, you are going to spend a phenomenal amount of time and money for any fix, and all are just band aids for something truly not worth saving.

Your frost heave issues are due to poor site preparation. Please read this information about properly preparing a site: https://www.hansenpolebuildings.com/2011/11/site-preparation/

and preventing frost heaving: https://www.hansenpolebuildings.com/2011/10/pole-building-structure-what-causes-frost-heaves/.

If you absolutely insist upon saving your pole barn, you should hire a geotechnical engineer to evaluate your site and give you expert advice. If you decide to give your barn a proper burial, start over with engineer sealed plans and a kit that gives you a lifetime of safe use…for you and your horses.

 

 

 

 

Installing Insulation, Properly Treated Posts, and a Slab Solution

The Pole Barn Guru helps with installing insulation in wet seasons, properly treated posts, as well as a solution to embedded posts when bedrock is present.

DEAR POLE BARN GURU: Hello. I am ready to install the insulation and metal on our pole building’s roof. I remember reading how it is important to install the insulation and roof when things are dry as to keep the insulation dry. We have recently moved into a rather wet early fall, and dry weekend days have seemed very illusive.

Do you have any expert ideas or advice that you may be able to offer us? I appreciate all of the very useful help and insight you’ve provided us numerous times already! BRAD in MOUNT VERNON

DEAR BRAD: You want to avoid trapping water between Radiant Reflective Barrier and roof steel, as it can lead to premature deterioration of roof steel.

A helpful hint – in rainy weather only place one run of barrier and if upward surface gets wet, towel dry it and immediately install steel roofing to cover.


Just one reason I now recommend using roof steel with an Integral Condensation Control: http://www.hansenpolebuildings.com/2017/03/integral-condensation-control/.

DEAR POLE BARN GURU: Opinion in using 9” x 25’ class #3 pressure treated utility poles as columns or posts? I have come across a grip of poles in coastal pacific Mexico. Pondering the use of them as my columns/posts in cabin and deck style construction. Their structural and dimensional properties suited for use as such? Thank you. CARL in ZIHUATANEJO

CARL: I personally would not want to use them as level of pressure preservative treating (as well as chemicals used) could very well be iffy at best, toxic at worst. Read more about utility poles in post frame construction here: http://www.hansenpolebuildings.com/2012/11/used-utility-poles/.

 

DEAR POLE BARN GURU: 26’ x 42’ pole barn planned. We hit rock 6” down. Builder now wants to consider option of to pour the 4” slab first and use post saddles to anchor the posts on top of the slab. He says “This is a good option and results in longer life of the treated posts. Included in this option is additional bracing on each post” Is this really a viable option???

Help! Thank you. VICTORIA in FAIRVIEW

DEAR VICTORIA: Unless your builder can provide engineer sealed plans for your building including his “solution” fire him now because he has no clue.

Why do I say this? A four inch thick concrete slab only will provide inadequate to mount a building to.

In photo of correct bracket below, concrete would need to be deep enough to have rebar entirely embedded in concrete:

 

While a properly pressure preservative treated column will last longer than any of us will be alive to witness, of course if it does not touch ground it eliminates potential of any decay due to ground issues.

Read more here: http://www.hansenpolebuildings.com/2016/12/attacking-pole-barn-rocks-holes/.

 

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.

 

Design for Spray-Foam, Sonotubes, or Proper Fasteners!

DEAR POLE BARN GURU: My name is Wade, I purchased the design and material from

Hansen for my pole barn this past year. It is a 64×64 Pole Barn. My question is, what’s the best way to insulate with the wall girts being horizontal and at an odd measurement on center? Thanks WADE in HILLSBORO

DEAR WADE: Thank you very much for your investment in a new Hansen Pole Building. If you have an opportunity to do so, I would enjoy seeing photos of your completed building, as it has some unique features which other clients would appreciate seeing.

Insulating buildings, after the fact, is one of the most common questions I get asked about. If we were in the design phase of your project, my advice would have been to place the bookshelf girts at 24 inches on center

(https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/) and use housewrap between the girts and the siding. As we are past this point, my best recommendation is going to be closed cell spray foam (read more about spray foam here: https://www.hansenpolebuildings.com/2016/07/advantages-spray-foam-over-batt-insulation/). It is not inexpensive however it is very effective and can be sprayed directly onto the inside of the wall steel.

DEAR POLE BARN GURU: I am looking into building a pole barn. In my area up north (Alpena Michigan) the ground is laden with heavy rock. 2 ‘ below the rock is bedrock. How will one set the main post for construction?? Digging this rock out would be near impossible while at the same time keeping things plumb and square! Please help! CHRIS in ALGONAC

DEAR CHRIS: I’ve actually been to Alpena! My first choice is always to dig holes to solid bedrock, probably requiring a backhoe. If the rock is such as to leave you with craters, sonotubes can be used to reduce the amount of concrete backfill required around the columns. If the bedrock is fairly shallow, or not below frost depth, the columns can usually be designed by the building engineer to be rebar pinned to the bedrock to prevent movement.

DEAR POLE BARN GURU: I recently bought a property and the 20 yr. old pole barn that is leaking inside from the eves on the sides. I have excessive overhang 4.5 inches on one side and 5 inches on the other. According to your sight, it should be 1 1/2 to 1 3/4. How do I repair/fix this problem?
Thanks, DALE in NEWPORT

DEAR DALE: Your challenge probably has nothing to do with the distance the roof steel overhangs past the sidewalls. The ideal length (1-1/2 to 1-3/4 inches) is based upon getting the runoff water from the roof directly into a gutter, without having the water just sailing over the top.

If your building is only leaking along the eaves, then it is a function of the original builder having used the industry standard #9 diameter screws. Over time, the cyclical nature of windloads will cause these small diameter screws to act like knives, cutting away at the surrounding steel until slots have formed around the screws – and water then leaks through the slots.

Provided this is indeed the problem, and the slotting is not too excessive, it can be fixed by using #14 diameter screws, which are greater in length than the existing screws. Remove all of the current screws at the eave, place the larger and longer screws back through the same holes and as long as no slots extend past the grommets, you have the job half done.

screwsProbably the roof only has screws on one side of the high ribs along the eave, if so, add another large/long screw at the other side of each high rib. The eaves and ridge are where roof shear forces (from wind) are the greatest. By adding the extra screws, it reduces the lateral force on each of the screws along the eaves.

If the slots are too great to be covered by a new fastener, the solution is to replace the roof steel and install it using the correct screws and with a pattern which will prevent the same problem from happening again in the future.