40x40 Pole Barn, Looking for Insulation Ideas

[MartyT]

New guy here, looks like a real friendly place. Hope someone can give me a few ideas...

Here's my building in a nutshell: 40x40x12 pole barn, corrugated metal on roof and 3 sides; one side has OSB and stucco. 4:12 pitch roof, trusses on ~13 ft centers, trusses designed for 0 psf bottom chord load. Currently have A1V bubble insulation between roof metal and purlins. 12" vented soffit all the way around, plus vented ridge cap. 3 ft "eave lights" (polycarbonate panels) on two sides.

As you can see, I was thinking "summer heat", not "winter cold" when I built my garage... Now that it's cold, I'm kicking myself for not thinking farther ahead. Note that I'm only looking to take the chill off for a few hours at a time....

So far, I've done the following:

* Installed a 75K BTU Reznor propane hanging furnace at about 12 ft. Finding it to be largely ineffective due to building size - just not enough air movement to do any good, especially considering 1600 sq ft of very cold concrete on the floor...

* Sealed the soffit vents by installing foam "plugs" between roof purlins at both gable ends and along the sidewall where the vents enter. That made a big difference as air infiltration was reduced considerably.

Now I'm trying to figure out what else I can do that will make best use of my money. Considering the following, looking for any input:

* Replace 75K BTU heater with 125K BTU model. Almost twice the BTU output and more than double the air movement.

* Install Kraft faced fiberglass bats between roof purlins (already have a foil/bubble vapor barrier under the metal). Not sure this is a workable idea or not.

* Install foil-backed insulation board on the walls between the horizontal girts (2x6 girts, on edge not flat "barn" girts). Concerned about leaving the foam board exposed to the interior of the garage, but suppose it's no more of a fire hazard than the rest of the exposed wood.

* Wondering if it's possible to "re-engineer" or otherwise beef up the trusses I currently have so they will support a full 5 psf ceiling load. No idea what would be involved to do that.

As you can see, lots of ideas but no clear direction. Hoping some of you who've "been there, done that" can give me some pointers!

Thanks

 

[Highbeam]

To keep your thread alive, I'll add a little. My pole barn also has huge truss spacing. 12 feet apart but I did have the trusses designed with a 10psf dead load. The dead load was already built into the design just to get the top chord loads to wrok out so maybe your trusses can be checked out by the manufacturer to see if they can allow some bottom chord dead load.

With the huge truss spacing I went in between the trusses with joist hangers and installed 2x6 ceiling joists on 24" centers. This to allow attachment of a ceiling to provide air seal and which would support insulation. I am now sticking the walls between the poles to insulate and sheet the walls.

With your ceiling, and mine, a low weight ceiling solution is metal ceiling panels from the siding manufacturer. They are lightweight, easy to install, and high gloss to reflect light. Also, not sensitive to moisture as sheetrock.

 

[67Stang5.0]

I just replaced the roof on my 38'x40' building and used the old roof inside as a ceiling. Worked very well. Put plastic sheeting up as a vapor barrier and will be blowing cellulose in to insulate the ceiling. My trusses are 5' on center and the metal roof material is very sturdy and has really stiffened the building.