# Garage insulation



## chiraldude (Nov 16, 2013)

I have an uninsulated attached garage. The garage door is somewhat insulated with some sort of foam core. I know what kind of insulation I want to add to the walls but the bigger question is what to do with the ceiling. There is no ceiling, just the roof trusses. I am looking for a low cost "ceiling" idea. Aesthetics are not much of a concern. I just want some way to suspend some insulation at the base of the trusses.
My current idea is to add some blocking 2x4s between trusses and put foam board on top of that. Then, possibly, fiberglass batts or blown insulation on top of that. 
I don't want to heat the garage all the time. Mostly want it insulated so it is slow to freeze in the winter with occasional use of a propane space heater when I need to work on something.


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## Windows on Wash (Aug 30, 2011)

I wouldn't both with the low cost option.

Putting up drywall isn't that much more expensive and it will be the proper way to do it. 

Stapling some sort of housewrap or plastic up is not advisable nor is leaving the fiberglass exposed. 

If you drywall it, you can blow in loose fill and actually have it work for you to help insulate the garage so the temps are palatable.


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## joecaption (Nov 30, 2011)

Both foam, paper face fiberglass and your local codes will state it can not be left exposed.
In fact there was suppose to be 5/8 fire code drywall all the way from the foundation to the roof air sealing off the garage from the house.
Rent a drywall lift and install 5/8 fire code to the ceiling and insulate with blown in as suggested after adding baffles to keep from blocking off the air flow from the soffits to the roof venting, all openings where wires or plumbing was run must be sealed with fire rated caulking or foam.


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## chiraldude (Nov 16, 2013)

I thought about drywall initially but I don't think the structure could support that much weight. The trusses are 3' on center which seems barely adequate as it is. 
As far as fire rating goes, the exterior walls are covered by 1/8" wood paneling so there wouldn't be any point in making the ceiling fire resistant.

The wall connecting with livings space is finished with 5/8 drywall all the way up to the roof deck so there is a good fire barrier where it counts. Apparently the garage was considered an expendable afterthought 30 years ago.


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## Windows on Wash (Aug 30, 2011)

Put some purlins or strapping across the underside to bridge the added span.


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## Gary in WA (Mar 11, 2009)

Sounds like rafters at 3' apart..... strapping may be too much weight with insulation and some covering, picture would help... http://www.diychatroom.com/f98/

Gary


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## chiraldude (Nov 16, 2013)

I measured and the trusses are actually 4' apart. Now I am more concerned about whether I need to add more structural support. I didn't see any obvious sagging but, just to be safe, I shoveled the snow off the roof. It was 2 feet deep on the downwind side so if it was holding that, it must not be too bad.
But, I have notice that the 2x4s are nailed with framing nails. I don't see any nail plates and there a number of places where someone has nailed pieces of plywood over the connections for reinforcement. At the very least I will want to do some serious reinforcement of what is there but I think adding a few extras trusses will have to happen before I get to the insulation.


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## dusty247 (Feb 3, 2014)

The drywall is the way to go. But blown insolation is messy and if you use the attic for storage every time you go up it is dusty. My suggestion is use fiberglass roll insulation and staple it up to the roof rafter then drywall. Leave room for access if you do use it for storage. The project will cost a little more then using blown in insolation but you be happier with the job. ONLY IF YOU USE IT FOR STORAGE. If not use the blown in insolation. 

Reading the rest of the remarks that you and others have made. Trusses are to be 24" on center 48" sounds like someone didn't follow code, and is not structurally sound. With a heavy snow year it is very posable the roof could cave in.


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