I am remodeling our garage which is heated and air conditioned. I want to reinsulate the ceiling and install vents to stop condensation from forming. The roof construction is 2 x 6 rafters, can I use Owens Corning Foamular F-150 2" thick? Must I leave a 1" to 2" air space between the foam and the plywood roof and install roof vents? Which roof vents work the best? How many vents? Garage size 22' x 32'. The ceiling will be vaulted and sheet rocked. Location: Minnesota.Thank you.
Last edited by langseth; 03-02-2012 at 12:10 PM.
Reason: added location
Your going to need soffit venting, foam baffles, ridge venting.
2 X 6 rafters will not give you enough room for much insulation. It may be best to at least add 2 X 2 straping to the bottom of the joist so you could at least get R-19 in there.
It's often better to have the bays spray foamed, or insulate the roof as well as the ceiling to give you the total insulation you need.
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