Adding insulation in attic

[fairway605]

Have a 22x 28 garage with storage trusses, I have 6 inches of insulation in the ceiling. Attic is storage 8 feet down the middle that leaves 7x28 down each side that I could add more insulation. So is it worth blowing more insulation in the sides but not middle section? garage is heated full time 55 degrees.

 

[matt_i]

What is the original insulation? Fiberglass?

I think you'd be well served to think about the possibility of removing the floor, furring it up 3-1/2 to 5-1/2 inches higher with basic 2x blocking, and insulating the entire thing to a depth of 9-10 inches. Then reinstall the floor. Ideally you want R-30 or more. The long heating season of the U.P. plus constant 55F says I think you'd be money ahead over the long run considering energy costs with a full complement of insulation. I know that it will reduce the overhead room but in my mind its a better trade.

Realizing its easy and cheap, I'm not totally convinced that blowing cellulose over fiberglass is the best plan, the original owners of my house did that in the attic and it seems to me like it over-compresses the fiberglass, which reduces its R-value. Somewhere way down on my project list is to remedy that but its going to be a nasty job as there are very few days when its good to work in the attic.

 

[NUTTSGT]

I'd fill the sides in with blown, either fiberglass or cellulose, since you really don't need to get back in there. A point somewhere level to the top of the OSB storage skirting and the foam baffles on the other side.

The center area is nice to have open but how much do you really need ? The attic our house was like that, blown edges and floor down the center. I effectively cut the storage space in half. I rolled a double layer of rolled fiberglass right on top of the floor. I also blanketed the cellulose with two layers of R11 fiberglass in a crisscross pattern.


If we need more storage, I can just move the rolls and put on top of what is already in place on the sides. You could easily do the same.

 

[Boilerhouse]

Your situation is very similar to mine. I am thinking of adding 6 inch batts to each side of the attic trusses, and adding 2 inch foam boards on the ceiling, under the attic space, and covering that with drywall.