An Excel Formula for Calculating Wall Girts, Post Size and Hole Depth
John Minor and I have been friends for nearly 30 years – since his then father-in-law (and my business partner at the time) convinced me John could sell post frame buildings. Well Rod was correct, John could sell buildings – not only for me (twice), but also for some of the better known names in the post frame industry – Morton, Stockade, Cleary and FBi just to name a few.
John is also a cutting edge innovator and has gone from selling post frame buildings, to manufacturing and providing components to the post frame industry. Current he owns and operates Central Perma-column (https://www.heartlandpermacolumn.com/). John is smarter than the average bear and he has the thirst for knowledge which few non-RDPs (Registered Design Professionals – architects or engineers) in the post frame industry do.
December 13, I received this text message on my phone: “I need your help with something”. Although I did not recognize the number it came from, it turned out to be John.
The conversation went on like this – John, “No worries. I’m trying to find an Excel formula for calculating wall girts, post size and hole depth.”
Me, “You would have to write one and they will be very complex due to the tremendous number of variables involved. I’ve thought about having a Wall Girt calculator on our website for Building Officials to use and the reality is, it is a huge undertaking. For it alone, requires all of the building dimensions including roof slope, is building enclosed or partially enclosed? Which means one has to know if doors are wind rated, and where they are placed. Also makes a difference as to where girts are located on building as wind forces are greater at corners. If girts are barn style on outside of columns, do they span a single bay or multiple bays? Then one has to account for lumber species differences as well as visual vs. machine grading.
Best bet would be to layout all of the parameters and put it out for bid on Upwork. Should specify which versions of Code and NDS you want to cover as well as it must conform to the NFBA design manual. For columns, you are now talking 25-35 pages of calcs.
Those “simple” pole barns one drives by every day are in reality highly complex engineered structures (when properly designed). A full set of calculations for a small two car garage can generate nearly 200 pages of single spaced calculations to prove the adequacy of all structural members and connections, from the footings to the last fastener.
Don’t leave your new post frame building to chance – insist upon having only a building which has been designed specifically for you by a Registered Design Professional, on your site, with your dimensions and your doors!
DEAR POLE BARN GURU: Do you have to use the same size posts on the end walls even if it is non load bearing? so if I use 6×6 posts that hold the trusses can I use smaller lumber on the non load bearing ends?
Thank you. CAMERON in BOISE
DEAR CAMERON: This is why it is essential to invest in a post frame building kit package which includes engineering which is specific to your building. The engineer will specify the minimum size requirements so you do not have to get into guesswork. Most pressure preservative treated timbers in your part of the country are Hem-Fir, which has a very low value in bending once it has been incised. Chances are very small of a 6×6 working to support the interior trusses, unless you have a very short eave height and a protected site.
In direct answer to your question – often the endwall columns can be smaller dimension. This article explains some of the reason why: https://www.hansenpolebuildings.com/2014/08/lumber-bending/.
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 is no simple task as the opening sizes are completely different. If this is the direction you truly want to pursue, you should start by contracting with a competent local engineer who can evaluate what you have and determine how to best make the structural changes necessary to fit the overhead door into your soon to be remodeled building. Expect this to be an expensive undertaking, even if you are doing the work yourself.
If you decide to just replace the sliding door, visit the ProDesk at your local The Home Depot®, as they should be able to assist you.
DEAR POLE BARN GURU: I recently purchased a pole building with vinyl insulation that is really dirty. Is there any way to clean the insulation? Can I spray paint it? I’m afraid to get it wet. Let me know your thoughts asap. Thanks LUCILLE in McHENRY
DEAR LUCILLE: You are finding one of the reason I personally do not recommend the use of vinyl faced metal building insulation. As long as the insulation has not gotten brittle and cracked, you can wash it with any sort of cleaner which does not react negatively with vinyl. Most folks who get to this point use dishwashing detergent, warm water and a sponge. Take care to not rip the vinyl facing. Any cracks or tears in the facing need to be repaired with a good vinyl repair tape (white duct tape works). I would not suggest power washing, as the force of the high pressure water will probably rip the facing, leaving you with an even bigger mess. Spray painting would not be an option unless the facing has been cleaned, at which point there would be no reason to paint it.