Insulating between exposed trusses...advice needed. Pics included

[bobforapples]

It's -5F today The polar vortex is in full swing and I'm re-evaluating my insulation plans for my pole barn addition.

I was going to use paper backed fiberglass on the bottom cord and sheath the ceiling with OSB. Heating is a mix of forced air and radiant floor. As I was playing around in the barn yesterday I realized my thermostat was set around 50 degrees and I was comfortable. I'm wondering if I'm wasting time + money.

What if I use white rigid foam insulation against the roof sheathing in-between the trusses? I can cut it to fit tightly and glue to the roof. The top cord is 2x4 so I'd probably use 1.5" insulation. I know the R-value isn't nearly as high as the fiberglass, but will it really matter if the temperature difference is 20-30-Maybe 40 degrees?

and a picture for reference:

 

[Jlbc212]

I vote for 9" thick unfaced fiberglass insulation with 4 or 6 mil poly vapor barrier. If the barn is attached to the house, cover with 5/8 drywall. Otherwise use OSB or 29 gauge ribbed metal roofing panels.

 

[dfiler2]

Yep, go with the thickest fiberglass you can get, you could use friction fit and tension wires then put on the poly and wall covering of your choice.

 

[DC73]

Read these:

How To Build An Insulated Cathedral Ceiling

Creating A Conditioned Attic

http://www.garagejournal.com/forum/showthread.php?t=280941


Also search for additional information on proper insulation techniques on both BuildingScience.com and GreenBuildingAdvisor.com.

Installing insulation directly against the bottom of the roof can be done but if you don't do it correctly, you are setting yourself up for problems with moisture, mold, rot, etc.

DC