Spray foam and fiberglass bats

[d.n.f.]

Howdy:

I am about to get my garage ceiling sprayfoamed (living space above). There will still be a ton of room in the cavity so was wondering if I can throw fibreglass bats in there or not?

I am asking because I know the spray foam acts as a vapour barrier as well and was wondering if putting fibreglass on the cold side would make any difference to anything. I know that the barrier in walls is on the warm side so would it kind of work the same here?

I guess I am just looking for confirmation of my stupidity...

 

[JustWood]

Why not have the contractor spray an extra inch and be done with it . Prolly not that much more since he is already there. Might not be as much as bats.
My shop has 1.5" and you could literally heat it with a bunch of candles.

 

[d.n.f.]

Well I have some water drain pipes at the lower end of the space cavity. That was more of my concern.

 

[mn_jon]

you should be able to combine the two. Our insulator was going to use 3 inches of foam on the walls with fiberglass over it. You do need a certain amount of foam to provide a vapor barrier but I am not exactly sure how much. We ended up filling the 2X6 cavity with eurythane foam. I guess also it depends on the foam. There is Icenine (spelling?) and eurythane. The foam is considerably more than fiberglass but has so many advantages. We used it for our attached garage ceiling because we had to get the most insulation per inch of thickness , between the garage ceiling and the storage area floor. For the attic above the house we just blew in fiberglass to achieve R60. I think you'll love the spray foam insulation.



Jon