Bookshelf Girts aka Commercial Girts: What are they?
I do a lot of blogging, not because I enjoy it (which I do) but because I am always “listening” and learning. And if there is anyone out there who I can help along the way, my fun increases exponentially. I recently came across this posting on a Farm Forum:
I am going to build a new shop building and wish to be able to finish the inside, insulation, sheeting, etc. I am in Minnesota, so it has to be fairly energy efficient. I saw some brief info on the “bookshelf method” in a pamphlet I picked up from a store. Looks like a super way to provide the desired structure on the inside of the wall surface to fasten sheeting to, and provide spaces for fiberglass batts laid in there horizontally. Very material efficient method, I believe. If anyone here has used this method, please share your experiences with it, pictures too if possible. Even if you have seen one built, like by a neighbor or friend, please speak up and share.
In case you do not recognize the method by the name I gave it (bookshelf), it is a technique which puts the wall girts between the posts, laid flat, typically 2×6’s, 24 inches on center vertically spaced (instead of the usual girt method which puts them on the outside of the posts). The pamphlet says they can be toe-nailed (?) or little nailers installed above and below them, for fastening to the posts. The pamphlet says wind loading is increased with the bookshelf method. The real attractive part of this method for me is that the 2×6 girt is available to the outside tin for fastening, then provides a 22.5 inch tall space for fiberglass bat (off the shelf size for between trusses on 24 inch center) and then is flush to the inside of the wall for interior wall sheeting fastening.
I’ve done several thousand pole buildings using the “bookshelf” or “commercial” girt method. I have two of them myself – in Northeastern WA, so have cold climate to contend with.
Use a commercial girt one size larger than the columns (2×8 on a 6×6 post, etc.), setting the commercial girt so 1-1/2″ hangs past the exterior face of the column. Wrap the framing with a well sealed high quality building wrap.
You will find this installation method compensates for any irregularities in the column dimensions and creates a deeper insulation cavity. Side benefits – electrical can be run around the outside of the columns, without the need to drill through them to run wires. On walls which are a multiple of 3′ in length, it also saves having to rip the edge of a panel off either the first or last sheet of steel on the wall.
In either case, block the ends of the bookshelf commercial girts solid against the columns with what is called “bearing blocks”. Take 2×4’s or larger (depends upon engineering) which are cut 22-1/2” long to fit between the commercial girts and install them flat against the post on each side. The wide face of the block should be flat against the column and lined up with the edge of the post (not sticking out past the column like the girts are). Nail these girt support blocks to the columns with a minimum of (2)10d galvanized common nails at each end (higher wind loads may require more nails). This type of nailing is quick and easy and provides a solid support for the commercial girt above it. Toe-nailing is done by angling a nail upwards from the bottom (or downwards from the top) of the commercial girt, at a 45 degree angle trying to catch enough of the edge of the post as the nail goes through to the column to hold it there. Toe-nailing is a very poor connection (is subject to lots of installation error).
For maximum cost effective R value, use BIBS insulation. I found it to be cost competitive with installed batt insulation, has a higher R value and completely fills all of the voids.
I fondly remember the gal who called me one day asking for “canning jar shelves”…you know like you did before for us.” Checking our records, I quickly discovered we designed commercial girts on their first building. They liked them so much – they wanted them again!
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