Tag Archives: Ultimate Post Frame Building Experience

Bookshelf Girts for Insulation

In the land where I first became acquainted with pole barn (post frame) building construction, was used a term known as commercial girts. These are actually what is more appropriately named “bookshelf girts” designed so as to create an insulation cavity which would extend 1-1/2 inches outside of the columns. The commercial girt is sized so the wall columns do not project inside of the plane of the bookshelf girts. An example would be using a 2×8 girt on 6×6 columns.

Reader Matt in Poland writes:

“Hi Mike, I didn’t come across your blog until after we purchased our pole barn package (not from Hansen) and were getting started. Our mistake, but we have learned so much from your blog.

My question is around the “illusive” commercial girts aka Bookshelf girts. When I say illusive, it is because, there are only about 2 internet postings about them, both belonging to you. We put standard 2×4 girts on the outside with Housewrap then metal. Now we are working on starting the interior and are going to go with 2×8 commercial girts inside. My question is running exterior wall things such as some plumbing, Gas lines etc. I do understand the electrical can run down the face of the post and has a 1 1/2 channel to do such, but what about those other things for rough-in.

We have taken a lot of pictures, and hope to post more information about our current build so that others can hopefully gleam information too.

Thanks Matt”

Matt’s kind words are of course much appreciated. The Hansen Pole Buildings’ “Ultimate Post Frame Building Experience™” is crafted with the idea of delivering the best value post frame building kit package to best meet with the ultimate needs of the client. In the case of Matt, it sounds as though his particular supplier may not have asked enough questions to have truly given to him the best design solution.

I will surmise Matt’s building has 6×6 columns with 2×4 “flat” girts placed on the exterior of the wall columns. As the bookshelf girts are being used to provide a surface for interior finishing only, it is possible a girt size as minimal as 2×4 could be used, holding the girt flush to the inside of the columns. Not only would this prove to be a greater cost savings, it also eliminates the transfer of heat and cold through girts which would touch both the exterior and interior finish surfaces. This type of interior commercial girt only needs to be stiff enough to resist undue deflection of the gypsum wallboard. This deflection limitation is to prevent taped joints from cracking.

As much as possible plumbing should not be run through exterior walls, especially in climates where freezing is possible during winter months.

The are some Building Code limitations as to the size of holes which can be drilled through sawn lumber, this excerpt is from the IRC (International Residential Code):

IRC R802.7.1 Sawn lumber.

“Notches in solid lumber joists, rafters and beams shall not exceed one-sixth of the depth of the member, shall not be longer than one-third of the depth of the member and shall not be located in the middle one-third of the span. Notches at the ends of the member shall not exceed one-fourth the depth of the member. The tension side of members 4 inches (102 mm) or greater in nominal thickness shall not be notched except at the ends of the members. The diameter of the holes bored or cut into members shall not exceed one-third the depth of the member. Holes shall not be closer than 2 inches (51mm) to the top or bottom of the member, or to any other hole located in the member. Where the member is also notched, the hole shall not be closer than 2 inches (51 mm) to the notch.”

This would allow for a hole of up to 1-13/16 inches to be bored through a 6×6 column, without adversely affecting the strength of the column.

Planning on climate controlling your new post frame building? Discuss the options with your Hansen Pole Buildings’ Designer to arrive at design decisions which will best meet your needs today, as well as in the future.

Why Not Use T Girts?

Last August one of our clients in Colorado invested in a new Hansen Pole Buildings Monitor style building. One of the features of the building was for it to be drywall ready. The
typical method we use for this is what we refer to as “commercial” girts – basically they are bookshelf style girts, set 24 inches on center, sized to match the columns and it includes a pressure preservative treated mudsill to set on top of the concrete floor, as well as the necessary backing at the top of the wall to support drywall.
For more reading on commercial girts: https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/
This particular client is in an area where the design wind speed is 115 mph (miles per hour) and this particular site has an Exposure C.
Learn everything you ever wanted to know about wind exposure and then some here: https://www.hansenpolebuildings.com/2012/03/wind-exposure-confusion/
It turns out or client hired a perhaps less than qualified builder to construct his building, and along the way had to dismiss him and find a replacement builder.
Keep in mind, the modern Hansen Pole Building is the result of input from people who have collectively constructed hundreds of thousands of buildings. Our team here is always “ears open” to ideas which make for a better building, without adding astronomically to the investment.
This is part of the culture of delivering the “Ultimate Post Frame Building Experience™”.
New builder made this suggestion:
“If you are open to suggestions, the next time you sell a building such as this and the buyer wants to finish the inside, use 2×6 wall girts laying flat in between the post and a 2×6 wall girts attached to the outside of the post , nail them together in the shape of a T. It would cost less, be stronger, easier and faster to build.”
Let’s see if new builder is correct in his recommendation.
On this particular building, the sidewall columns are 3 ply 2×8, which requires a 2×10 commercial girt. To make builder’s suggestion work, it would take a 2×6 on the outside of the column and a 2×8 placed bookshelf style.
For sake of pricing discussion, I have used numbers from the closest The Home Depot® to the client, which is in Colorado Springs. Our version (the 2×10 10 feet long) weighs in at $10.93. The builder’s version (a 2×6 and a 2×8 10 feet long) come in at $6.37 and $8.46 for a total of $14.83, so certainly not less expensive in the materials portion.
Looks to me like the builder’s less expensive version comes in at over 35% more expensive!
How about strength?

The combined 2×6/2×8 mix has a Section Modulus of 15.203. while the single 2×10 is 21.3906. Now the combined mix gets to use a base Fb (Fiberstress in bending) value of 1020, the 2×10 only comes in at 935. Doing the math the combined method is 15.203 X 1020 = 15,507 in-lb, the single 2×10 21.3906 X 935 = 20,000 in-lb.
Hmmmm – the building as designed would have wall girts nearly 29% stronger than the builder’s “stronger” method.
How about easier and faster to build?
Well, it now involves having to cut two boards and nail them together as a T, rather than cutting and installing a single board. Not seeing how this is faster.
Unless – builder is thinking he will not have to place blocks under each end of the bookshelf girt.
The suction force on the end of each of these wall girts amounts to 258.25 pounds. I don’t know what the builder was planning upon using for nails, but with the recommended 10d common nails, the withdrawl value is somewhere around 37.5 pounds per nail. Factoring in the DOL (Duration of Load) factor for wind, this would amount to having to place 5 nails into an area roughly two inches by five and one half inches.
Could it be done? Maybe, but methinks it will result in a poor result – both cosmetically and structurally.
In addition, with no block under the ends of the 2×8 bookshelf girt it is going to be prone to some twisting issues.
Suggestion appreciated, however the verdict, in this case, is a resounding no.