When furring out is sill foam gasket enough of thermal break?
agurkas
| Posted in General Questions on
I am planning to furr out floor joist bays by another inch and a half. Idea I have is to use Owens Corning SealR Sill Plate Gasket cut into strips and put between joist and wood spacer for the furring strip. Does that create enough of a thermal break?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Apollo,
The thickness of the foam is 1/4 inch, so its R-value is approximately R-1.
Is that enough? No. Will it help a little? I suppose.
A better approach would be to install a continuous layer of rigid foam across the bottom of the joist bays.
Martin,
I looked into that and it was just too expensive for the budget I have to deal with that room. Reason for furring out is to create 1.5" of space bellow joists for cellulose to get into, so it would create thermal break.
I did think about doing the "sandwich" of cellulose in the bays, hosewrap stapled directly to the joists, and then 3" Roxul AFB I have sitting in storage. But it is less costly to do all cellulose than cellulose and Roxul.
Apollo,
If you are installing 2x2 or 2x4 strapping to the underside of your joists, install the strapping at 90 degrees to the joists. That will go a long ways toward addressing the thermal bridging.
Martin,
That was the original plan. I was also planning to only attach the strapping every other joist.
I actually found some XPS sheets I forgot I had. So I cut them into little blocks and will use that as spacer between strapping and the joists. That should provide for a nice thermal break.