This Wednesday readers “Ask the Guru” how to insulate a post frame ceiling that already has bubble wrap, how to wire for bookshelf girts, and how to set trusses where a crane is not an option.
DEAR POLE BARN GURU: Best and easiest way to insulate the sloped ceiling in my pole building? it already has a single bubble wrap. see attached picture. I appreciate any help you can give thank you. BRIAN in LEXINGTON
DEAR BRIAN: Rip out single bubble wrap between purlins and roof steel. Have closed cell spray foam applied directly to underside of roof steel. Those 2×4 roof purlins will allow for 3-1/2 inches, totally filling cavity. This will give you roughly R-24. You could then apply a light-weight flexible finish material to underside of purlins (something like steel liner panels). You may find it necessary to mechanically dehumidify building to prevent excess relative humidity.
Your building’s roof system is also missing some things. Roof purlins should be connected to truss top chords with joist hangers. Required 2×4 bottom chord bracing is also not present. There should be 2×4 no greater than 10 foot on center, running from endwall to endwall. This prevents out-of-plane buckling. Easiest application would be to use Simpson SDWS16300 screws to attach alongside endwall columns – then use joist hangers to attach to truss bottom Chords.
DEAR POLE BARN GURU: Post frame building with bookshelf girts. Siding attached to bookshelf girt and posts. Want to attach drywall to other side of post. How do I run wiring? I guess drill. How large of a hole can I drill through the support posts. Any other options? Thanks JOHN in POULSBO
DEAR JOHN: Very little drilling, if any, will be needed for holes in order to run electrical wires. Wall framing (girts) extend or are placed so as to leave a 1-1/2 inch space between outside of wall columns and siding.
Think of a hole being drilled through as being an “open knot”. Lumber grading rules refer to these as being “Unsound or Loose Knots and Holes” due to any cause.
For #2 graded lumber holes may be no less than every two feet and up to 5/8” diameter in a 2” nominal face; 7/8” in a 3” nominal face; 1-1/4” for 4”; 1-1/2” for 6”; 2” for 8” and 2-12” for 10”.
For higher grades holes may be no less than every three feet and up to ½” diameter in a 2” nominal face; ¾” in a 3” nominal face; 1” for 4”; 1-1/4” for 6” and 1-1/2” for 8” and wider.
Any holes drilled through pressure preservative treated lumber or columns, especially near grade, should be treated with a Copper Naphthenate solution. Copper Naphthenate is available as a brush-on or spray-on.
DEAR POLE BARN GURU: Hello,
We are trying to identify our options for setting 7 trusses in a space inaccessible for a crane or equipment that could use a hoist of any sort.
We’d like to estimate the weight of each truss while we wait on quotes.
The span is 16′ + 1′ overhang each side, 6/12 pitch, designed for 4′ centers spacing and carry total load (including our snow load) of 90 lbs.
We hoped to prop up 1 end on the top girder, or beam, then carry up the other end on a ladder to the beam on that end. Then hope to “flip” or rotate the apex upright with a 2×4.
Is there an easier way, given only about 4 people to do this & only 1 of the 4 is a brute?!
We are in Upper Peninsula of Michigan, snow load requirements of 90lbs.
Steel roofing, no ceiling ever- just a tractor barn/wood shed.
Thank you! KAREN in MICHIGAN
DEAR KAREN: They should weigh just under 90 pounds each. Your described flipping them up, should work well.
DEAR KAITLIN: Most pole barns are built either without being engineered or to Risk Category I. For residential purposes, it would need to meet more stringent structural requirements of Risk Category II. You will probably have to add some perimeter slab insulation in order to meet Energy Code requirements. My best recommendation is to engage a Utah Registered Professional Engineer to do a physical evaluation of your existing building and to design needed structural upgrades.
DEAR WESLEY: I have seen many far less well thought out wall systems without exterior sheathing not experience issues with condensation. As far as air sealing, you could get a blower door test done to find out exactly what your situation is. For extended reading, please see 
DEAR TRIPPE: We always suspend our columns eight (8) inches above bottom of holes and mono-pour footing and concrete encasement in a single pour (saves on paying for short haul charges). While concrete typically reaches 75% of compressive strength in seven days, when I was building we would pour one day and start building next day. For slabs on grade, it is recommended to not walk on them for 24-48 hours after a pour. Keep in mind, concrete compressive strength is in psi (pounds per square inch) and soil bearing capacity under footing is in psf (pounds per square foot). Most soil will support a maximum of 2000 psf or 13.88 psi, so your concrete (at 2500-3000 psi) is going to be much stronger, even after a very short time span, than soils beneath. You can increase concrete strength by ordering a higher cement mix and speed curing time by use of hot water (avoid use of chemical additives to speed curing).
International Residential Code (2021 IRC) Section R309.1 and International Building Code (2021 IBC) Section 406.2.4 address concrete floor slope: “The area of floor used for parking automobiles or other vehicles shall be sloped to facilitate the movement of liquids to a drain or toward the main vehicle entry doorway.” Floor slope by IBC only applies to “U” occupancy buildings of 1000 square feet or less. Actual slope requirement is unspecified however a generally accepted minimum is 1/8” per foot. Grade inside of building should be gradually built up to create this slope.
DEAR POLE BARN GURU: I have a 30×48 pole barn. 13′ at eaves/overhang and 19′ center height because of scissor truss. No windows. One man door and one garage door. It has closed cell insulation. Brown roof. Used for trailer/camper storage. Not a lot of work going on in this building. It stays a little cooler than the outside temperature but is humid with musty smell due to no ventilation. I would like to install a gable end louvered exhaust fan but everywhere i search i come up with different answers. I don’t need fast air movement, just replacement. i would like to know what size fan and air intakes are required to do this. Some of this information may be irrelevant but it was asked for among other inquiries. Thanks for your time and help. WILL in WINFIELD
DEAR BOB: This is one reason I like to build with my trusses directly attached to columns (using notches cut into columns to provide full bearing). After verifying trusses are exactly 16′ in length, trusses can be placed into notches, with outside of truss flush to outside of columns. This solves any width issues. Using recessed purlins, joist hung between trusses, purlins can be pre-cut to length of space between trusses, solving length issues. Once framing is completed, each roof plane can then be squared (read how here: 
