I have a standard 2-car garage and I'm finally looking to drywall the ceiling and insulate it so I can tolerate working in it during the Colorado winters.

I'm having a hard time determining the best method to insulate it. Most recommendations say R-38, but there are no living spaces over it, which makes that rating seem high.  I'll likely go with batts, but other than that, I'm looking for any expert advice.

I should mention that the garage has a ridge vent (was way hot in summer) and proper soffit vents. This is great for summer, but in winter the garage is about as cold as outdoor temps.

Thank you.

R-38 is code for sloped ceilings in a residence. It is higher for a flat ceiling. I don't think that applies to a garage, but it will pay you back with reduced heating costs.

If you insulate the slope you'll need to install proper vents, which are channels that go against the underside of the roof sheathing, to maintain the airflow.

You'll also need to install a vapor barrier behind the sheetrock on both the walls and ceiling.

It will be cheaper to heat if you just insulate the lower part of the garage, walls and ceiling, and leave the upper level cold.

...and it's always good to leave an access hatch (insulated also).

Thanks for the feedback. I'm not sure if I will heat it or not -if anything, probably just a space heater.  I don't plan to do the slopes, just the floor joists.  Given there'll be no climate control, is R-38 the best bang for the buck?  I know it's recommended for ceilings over living space, but I'm not sure about the garage. I haven't researched insulation cost yet, so I don't know...  They seem to recommend R-13 for the walls. I need to do the garage door, too, as it's aluminum and gets bloody hot during the summer. I also have to figure out a way to better seal the garage door, as I can see light passing through on the sides -don't know if the wheel brackets will give me that adjustability though...

Quote from: D3vi@nt on November 18, 2012, 05:52:33 PM
Thanks for the feedback. I'm not sure if I will heat it or not -if anything, probably just a space heater.  I don't plan to do the slopes, just the floor joists.  Given there'll be no climate control, is R-38 the best bang for the buck?  I know it's recommended for ceilings over living space, but I'm not sure about the garage. I haven't researched insulation cost yet, so I don't know...  They seem to recommend R-13 for the walls. I need to do the garage door, too, as it's aluminum and gets bloody hot during the summer. I also have to figure out a way to better seal the garage door, as I can see light passing through on the sides -don't know if the wheel brackets will give me that adjustability though...

If the walls are 2x4 then R-13 batts are all that will fit. 2x6 walls will allow R-22.

R-38 is a pretty good number. With a space heater it should be easy to make it warm enough to work on the bike.

If the garage door is leaky all the insulation is going to seem wasted. They do offer insulated garage doors, although getting it to seal well will make it more comfortable. Most wheels are adjustable, and replacement seals are around.

Around this area it is cheaper to hire an insulation contractor than going to a box store for materials and doing it yourself.

R38 is overkill in your application, you won't see any real difference in comfort or ease of heating then if you used R21.  As DP said, your biggest heat loss may be air from around the door.  If the door has no insulation at all you could cut 1" Styrofoam to fit the panels and use spray adhesive to keep them in place.  Bubble wrap/foil insulation also works pretty good in doors.  Look into Roxul instead of fiberglass.  It has a little better R value/inch but it's much easier to work with.  http://www.roxul.com/residential/products/roxul+comfortbatt%E2%84%A2

Cool. Thanks again for the replies. The door is definitely an issue. I planned to glue foam instulation to the panels, just need to make sure the added weight won't be a problem. The door has a little adjustability so i can start there and then see what I need for a full seal.  The Roxul stuff looks interesting -I'll check it out.

I have a split level house and was going to wire the garage for a more of a friendly work enviroment when I noticed the walls are insulated. I'll be watching this thread. I was reading up on the Roxul Comfort Batt before this thread, and I'm thinking of going this way.

Quote from: Scooter Montgomery on November 26, 2012, 10:34:24 AM
I have a split level house and was going to wire the garage for a more of a friendly work enviroment when I noticed the walls are insulated. I'll be watching this thread. I was reading up on the Roxul Comfort Batt before this thread, and I'm thinking of going this way.

You could always surface wire it with either EMT, MC (metalclad), or Wiremold.

Unless the inso was done poorly, it makes no sense to rip it out to wire.

I should proof read before I hit POST. The walls don't have any insulation in them. They are just sheetrocked. I'll be removing the sheetrock, wiring and insulating.

Another option

Spray Foam Insulation - The Intelligent Choice

Spray foam is great but more money. I know a guy that owns a spray foam company and after talking to him a would be leary of spraying during the winter. Temperature is very important to the quality of the foam instalation. Summer you have the best chance for good results.