Closed cell or open cell foam backer rod
user-7601308
| Posted in General Questions on
Do i want closed cell or open cell backer rod for the space between my window rough opening and window jambs?
also, my rough openings are a bit oversized with almost an inch on each side, and top and bottom between RO and window jamb. Is there an oversized backer rod that would be suitable?
And — do you install the rod on all 4 sides of the window? Do you push it in from the exterior or interior?
thanks,
forrest
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Replies
Forrest,
What kind of windows are you installing. Fanged? flangeless? wood with brick molding?
Non flanged wooden window frames.
Do I only put backer rod on the sill of the rough opening? And then just insulation between the sides and top?
Forrest,
As Andy said: Furring down the ROs so that you have about 3/8" makes everything much easier.
Then put the backer rod about half way towards the exterior and fill the gap with foam. You can add a bead of caulking at the interior face as further insurance.
The sill gets treated differently. It needs a sill-pan of peel & stick membrane placed in the RO before the window is installed. If the sills are not sloped it should be turned up to create a dam at the inside face of the window frame. A bead of caulking provides the air-barrier. No insulation is used.
"my rough openings are a bit oversized with almost an inch on each side, and top and bottom between RO and window jamb. Is there an oversized backer rod that would be suitable? "
An inch on each side seems a bit much. I'd be furring out that RO to be a little closer to the window size. I mean, how are these windows going to securely attach with that much of a gap? How would they be trimmed out?