Garage Ceiling Insulation

[carlsheritt]

I am putting a heater in my garage and I want to insulate the ceiling. The walls are already insulated. The building is a 30x30 steel building with a cathedral style ceiling made of 2x4s spaced 21 inches apart. I think I can only use R-13 insulation, but I can't find any in the 23 inch size. I can find R-19 in this size. I found CertainTeed insulation model 900355 and 900225 (r-11), but can't find any at Lowes or Home Depot. The price would be the same as R19 anyway. Can I just put up R-19 and stuff it in and get an r-13 value or is this a bad idea?

Any good ideas on retailers for insulation? Its pretty expensive. I'm near Philadelphia.

 

[GSSFC]

If you put in light duty fiberglass like that and heat the interior you are going to experience massive condensation problems in the roof. I would find a way to fur out the rafters or trusses so that you can install R38 fiberglass is that is the route you prefer. Or you can install 2-3" of closed cell foam and be better than anything else out there!

Tim

 

[carlsheritt]

Where can I purchase closed cell foam? Is it those thick foam boards?

Also, any other recommendations on a good method to insulate this without causing problems?

 

[kbs2244]

First, be sure to use a vented heater.
Second, plan on "wasting" some heat by keeping a
window open about 2 inchs.
Or go high tech with a humidistat controlled vent fan.
Heating produces humidity, and humidity is attracted to cold.
(Remember your wet beer cans, even on a dry summer day?)
Cold tools stored around the walls will get rusty if you don't plan on fighting dampness from the start.
Get at least 3 cheap celing fans and put them at the peak, blowing down,
and never turn them off.
The air circulation will help a lot, both winter and summer.

 

[carlsheritt]

I plan on using a Modine 75k btu vented heater and was thinking of putting some fans in. I don't have any windows to leave open.