Tag Archives: post spacing

Rebuilding, Post Spacing, as well as a Frost Wall

I this weeks blog, the Pole Barn Guru talks about, rebuilding a pole barn, ideal post spacing and a frost wall.

DEAR POLE BARN GURU: Hello, I recently disassembled a 36 x 100 pole barn and am rebuilding it at my house. It was covered with 2″ reinforced paper faced roll pole barn insulation with a 1″ foam board between the insulation and the metal. While removing the roll insulation it received many tears in the paper face. I would like to install a 6mil vapor barrier over my lumber then reinstall the roll insulation followed by the foam then the metal. Is this a good idea? The building will be heated and air conditioned but will not receive any kind of wall covering inside of the vapor barrier. Thanks DEAN in CORYDON

wind damageDEAR DEAN: I can’t say I am a huge fan of rebuilds for several reasons – damaged materials end up being used and it is pretty well impossible to keep from having holes in the roof steel which are going to cause leaks.

You should seriously consider the involvement of a RDP (Registered Design Professional – architect or engineer) to insure what you are rebuilding will meet Code requirements.

One problem right away – the foam board between the framing and the steel. Throw it away or resell it on Craigslist. The foam board pretty much negates the strength of the steel cladding due to the lack of rigidity of the insulation. It will also contribute to the possibility of slots forming around the screw shanks, due to movement of the building framework.

You should use a well sealed building wrap between the wall framing and the steel siding, then the insulation. If you are unable to repair the tears in the paper facing, you can use visqueen on the inside for a vapor barrier, however it (or paper facing) should be covered with an inflammable material to prevent possible fire issues.

DEAR POLE BARN GURU: Hello, I’m in Oklahoma which has high winds and severe weather. I am leaning towards having a garage built that is 20x24x10. How far apart should the columns be spaced? We have no HOA in our neighborhood and I haven’t reviewed the neighborhood covenants.  I’m really wanting to be smart on this because it’s a lot of money that I want to be solid investment. My goal is to save money, but be so cheap that building falls apart.  Thank you for your time. SHANE in OKLAHOMA

DEAR SHANE: The real answer does not come from column spacing, it comes from investing in a fully engineered post frame building which is specific to your building upon your site. Given your concern is for wind design, unless you have a site which is well protected from the wind in all four directions (buildings, hills or evergreen trees 30 feet or greater in height) you need an Exposure C for wind. You can get pricing on a variety of Vult wind speeds and determine what wind design you are willing to invest in.

 

DEAR POLE BARN GURU: I purchased a pole barn kit a couple years ago and I am just now getting around to building it. My county approved everything but they added an exception. They say that I need to add some frost protection. Either a frost wall or some sort of shallow frost protection. There are no plans for such in the blueprints and it is required by code here. So my question is what do I need to Do? Doing a concrete frost wall almost makes buying the pole barn kit unnecessary. I should of just did a stick built if I’m basically building a foundation.  I live in Bonneville county Idaho. Just wondering if you have come across this situation here and what the buyer needed to do? CAMERON in IDAHO FALLS

slab edge insulationDEAR CAMERON: You can do a Shallow Frost-Protected Foundation without having to thicken the slab edge – you can backfill on the inside of the vertical insulation board with sand. In the event your Building Official requires this to be added to your plans and sealed by the engineer, there would be an added investment for redrafting and sealing two new sets. For more reading: https://www.hansenpolebuildings.com/2016/11/frost-protected-shallow-foundations/.

 

 

 

 

To Remove, To Replace, and To Design!

DEAR POLE BARN GURU: Hey Guru! I’m getting ready to build a pole barn and I will have to remove a tree. The tree is basically right in the middle of what the floor will be. I will be putting a concrete floor in and was wondering do I have to completely remove the stump or can I just cut it down below grade and cover it with dirt and gravel? MARK in BROKEN ARROW
DEAR MARK: Completely remove it. You do not want any sort of organic material to remain under a building site. Eventually it will decay, sink and if you have poured a concrete slab over it, the slab could fail any you could find yourself parked in the bottom of a hole in the middle of your barn. Stump removal is relatively inexpensive – and it is something you could probably do yourself along with a properly sized piece of excavation equipment.

 

DEAR POLE BARN GURU: We have a pole building that had a 12’ X 12’ slider door that was recently damaged and needs replaced. Can you point me in the direction I need to go to get a replacement. We wanted to replace it with an overhead door but do not have sufficient clearance for our motorhome. JOYCE in FRANKLIN

DEAR JOYCE: Replacing a sliding door with an overhead door can end up being a near epic challenge as the opening sizes will not be the same. At the very least it will necessitate a custom width overhead door. Before you get too deep into the process, contact three local overhead door companies and ask each to come out to give you a quote on the door. They will be able to tell you what the maximum height is you will be able to get into your building (keeping in mind this may necessitate increasing the height of the door opening). Once this step is done, if you are not already over budget, run an ad on Craigslist under “gigs” best describing the work to be performed – which should include replacement of all of the steel siding on this wall of the building (otherwise it is never going to look right). I have no idea how large your building is, but could easily see this as being a three to five thousand dollar price tag before all is said and done.

Which leads back to – the solution might be to bite the bullet and just replace the sliding door with a new sliding door. You can probably get all of the needed components by a visit to the Pro Desk at your local The Home Depot®.

DEAR POLE BARN GURU: Storage for trailer 35 ft what is a pole distance set with 10 – 12 ft opening? TRACY in NAMPA

DEAR TRACY: I will have to read between the lines here and hope I am able to provide an answer which fits with what your question truly is.

For starters, if I had a 35 foot long trailer to get through a door, I want the opening to be about 12 feet wide. Going 10 feet wide appears to me to be risking some damage.

If the door is to be a sliding door, the space from center of column to center of column on each side of the door should be 12 feet. This will allow the sliding door itself (which should be about 12’2” in width to cover the opening and provide an overlap on each side.

For overhead doors, if getting a residential overhead door, the space BETWEEN the columns should be 12’1”, so as when the 2x jambs are placed on each side of the opening, the finished opening will be 11’10” in width. This will allow the overhead door panels to overlap by an inch on each side. For a commercial overhead door, increase the width between columns by two inches.

 

Pole Barn Post Spacing Revisited

Pole Barn Post Spacing Revisited

By far, my most read blog has been on, “Pole Barn Truss Spacing”. With nearly 50% more reads than any other blog I have written, it clearly is a fan favorite. I’ve had it referenced by clients, building contractors and code officials.

So when one of our clients wrote: “After talking with the building inspector he does not like the idea of post spacing 12ft apart with double rafters. Can you quote a standard setup so I can compare apple to apples, post 8ft on center with double 2×12 header and trusses every 4ft, no joist hangers needed for perlins?”, I felt obligated to answer.

(For clarification of the above, “double rafters” are “double trusses”.)

My response: While the building inspector may not “like the idea” of using post spacing 12 feet on center, it is not only a tried and true method, but it is also one which our engineers recognize as being structurally superior and will engineer seal. We have thousands of buildings in all 50 states, done with the exact same design. It affords the benefits of fewer holes to dig, fewer pieces to handle and install, engineered connections and the reliability of doubled trusses.

Given the correct loading criteria and an engineered building, we will guarantee the ability to obtain a structural permit from our plans. The post spacing every 8′, single trusses every 4′ resting upon headers is a system our engineers are not interested in risking their careers on. In the event of a single truss failure, this system will result in a domino effect and the collapse of the entire roof system.

After the winter ice storm of ’96-’97, I spent quite a bit of time studying roofs that collapsed -some of which were on my own buildings!  At that time, we were using two trusses on a pole, so we had this part “right”.   But instead of putting the two trusses together to act as a single unit, we put one on each side of the column with blocking in between.  The trusses were notched in, so this was another part we were doing well – transferring loads into the ground.  But the one part we missed, was putting the two trusses together.  Lumber is after all, a tree…with inherent knots and defects.  With the huge loading of ice that year…the truss “weak spots” gave way – and if one truss fails, it pulls the rest of the roof down.  This is when I asked an engineer to evaluate the truss system I was using as well, and he concluded the “probability of a second truss adjacent to the first one having the same exact ‘weak spot’ – just could not be calculated.”

From then on, I started using double trusses, nailed together according to a specific nailing pattern (supplied on all our plans).  Since then we’ve had other winters with similar ice/snow loadings, and…no more failed roofs!  I had the engineer’s word, but even better – I had real proof from thousands of buildings which survived nature’s “test”.  We’ve been using the double interior trusses ever since.  Only one roof I’ve seen fail since then…and it was determined to have been due to the two trusses were not nailed together adequately – they had few nails holding them together.   Again – the trusses acted as “singles” and pulled part of a roof down.

We get the requests for abnormal (for us) truss spacings or post spacing every once in awhile. Instead, I prefer to turn it around and stress our advantages –

(1) Fewer holes to dig, digging is always the worst part, and the one which is outside of anyone’s control. If they hit a Smart Car sized rock on the next to last hole, are they going to move the whole building?

(2) Fewer posts to set, trusses to raise, purlins and girts to handle. The real advantage of pole building construction is having the least number of pieces, in order to do the job structurally. By using slightly larger pieces (generally 2×6 instead of 2×4, where it takes only 50% more wood, to be 246% stronger) we are being material efficient.

(3) Wider sidewall door openings without the need for structural headers. In the event someone wants to add a door or window at a later date, they have far more flexibility to do so.

(4) Does anyone REALLY want to stand on a 2×4 roof purlin 16, 20 or more feet up in the air? When the 2×4 purlin snaps, it is a long drop to the ground.

(5) Most building collapses come from connection failures. In our case the purlins connect to the trusses with engineered steel hangers (not just nails); the double trusses bear directly on the posts (not on the sides of the posts, or nailed onto a header). The load is transferred down into the ground and is not dependent upon nails to hold the entire weight of the roof.

(6) If you think about it, if you have a 48’ long building, with single trusses every 8’, you have a total of 5 interior trusses.  If you have double trusses every 12’, you have a total of six interior trusses, but only have to dig 3 holes instead of 5. Which would you rather do?

By the way – our client DID get his building permit issued, using our plans, by the very same inspector who originally “did not like the idea”.