The pole barn Guru looks at a Retro-Fit, truss supports, and installing a sliding door.

DEAR POLE BARN GURU: I have a question about Retro-Fit insulating my pole barn. I live in Southwest Michigan and bought my house with an existing 40’x60′ building, just used for storing farm equipment before I acquired it. Steel roofing straight to the roof purlins and steel siding straight to the wall purlins. Can I put a metal ceiling in with blown fiberglass insulation above and metal walls with Batts between the inside wall and outside wall, or do I need to have some sort of vapor barrier? MITCH in MICHIGAN

DEAR MITCH: First things first, in order to retro-fit the trusses, confirm the trusses are capable of supporting the weight of the steel liner panels and insulation. Most post frame building trusses are not designed to support a ceiling. There should be a stamp on every truss which identifies the truss manufacturer as well as the design loads. You need a minimum three psf (pounds per square foot) bottom chord load to support the ceiling. If it is less, and you can contact the truss manufacturer who should be able to provide an engineered repair to upgrade the trusses, for a nominal fee.

You will need to have some form of thermal break below the roof steel – my choice would be closed cell spray foam. On the walls, you should really have a building wrap between the steel and the framing, however an inch or so of closed cell spray foam would work, filling the balance of the cavity with unfaced fiberglass, then a well sealed vapor barrier on the inside.

DEAR POLE BARN GURU: Pole Barn Guru, do you have to have girt under end trusses. End trusses setting on 2×12 from header and nailed to 6×6 pole with 2×6 blocking below trusses 24″o.c. sheated header 3 2×12 notch blocked and clipped. STEVE in CHEYENNE

DEAR STEVE: In order for me to answer your question, I would need to see the engineered plans for your building. If you are unsure of how to determine from your plans, you could contact the engineer of record who designed your building and ask him or her.

DEAR POLE BARN GURU: On a sliding 4×8 walk in door, on the barn exterior are all 4 sides flat or is the top out the thickness of say 1.5 inches? If it is out will it not seal? If all is flush with it not roll easy? Joe

Figure 27-5

DEAR JOE: The sliding door track needs to be mounted to a ‘track board’ which is typically a 2×6 placed on the face of the sliding door header. This puts the top out 1-1/2″ which allows the door to be able to slide past the adjacent siding without banging against it. Sliding doors do not and will not seal air tight, so this should not be an issue unless you had some sort of unrealistic expectations.