Attached Garage insulation question....

[Scarpozzi]

I just built an attached garage onto my house. I'm gonna have a bonus room/bedroom upstairs.

Typically, what kind of insulation do people install in a space like that in the ceiling. Winter is going to allow cold air to rush in those garage doors when a car comes or goes.... I'm just wondering what R-Value I should shoot for in the ceiling. I would consider spray foam or something, but it's a 30x30 garage and the ceiling rafters are on 12" centers....so spray foam will likely be a lot of work/cost that I'd rather not spend.

Thanks for any advice.

 

[ShadowVVL]

For shop/garage I would use r38 or 4inch thick sheets of polystyrene if you can get them.

I usualy just do 2inches polystyrene and put r19 over that for the walls and it works well.

ceilings I use r38 but you could do the polystyrene and r19 for that aswell.