Is spray foam the way to go? Is it a DIY project? If so where to buy it? Or will caulking and fiberglass do it? My basement walls are studded and insulated with fiberglass but the builder did not extend the fiberglass to the rim joists.
Thank You for your input.
Replies
I would use fiberglass batting. Fill the entire bay that of those that run parellel to the foundation, and cut pieces just long enough to extend in past your walls for bays that run perpendicular.
Another concern would be firestopping. Did your contract block the open spacing where the walls meet your ceiling?
J. D. Reynolds
Home Improvements
If you're referring to fire stops in the basement walls there are none. There is a sole plate on the basement floor and the studs run up beside the joists and are nailed to the joists. The basement walls just have the studs, insulation and a foil paper over the studs and insulation. The builder only built to code...didn't even provide a door inside the bulkhead...did that myself. With him what you see is what you get...wouldn't let him build me a dog house.
Thank You for your reply.
You did not give you location. But it is not unknow that in the colder climates that FG does not work very well in rim joist bays.
It is hard to get a a good vapor seal all the way around. Moist air can work behind the FG and condesnse on the cold rim joist.
A better methode is cut sheat foam and to fit and seal it in place. You can use either the foam guns or "caned" foam from the home horror stores.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I'm in Massachusetts just south of Boston. Condensation on the rim joists behind fiberglass never occurred to me. Thank You for the advice.
"Is it a DIY project? "
That is one of my questions...
;)
Get some foam panel and cut it on the TS to fit in. if you need glue/caulk use spray foam in cans or PL 300 but if this is new construction , the spaces will be all equal and you can get a tight friction fit for much of it.
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Fairly new construction...all bays are the same size. I would like to do it myself. If I were going to go the spray route I would consider hiring a pro.
I like the foam board idea. Shouldn't be too messy.
I use foam all the time, what I do is cut the foam an inch small in both directions, that way the spray foam can get in around and act as vapour barrier. I tack it in place with a nail or two. I like to use the foil faced iso board, but sm works too. The white stuff is not always dense enough to stop vapour.
As others have said, rip some dow blueboard, score and snap the widths for each bay as you go along, caulk perimeter of each bay with sealant.
Great thread. I am also south of Boston (cold in winter) and in the process of finishing my basement according the referenced article / Building Sciences method. Here's my question: rather than apply foam directly to the rim joist, can I run my 2" Dow XPS from the floor all the way to the ceiling, i.e. to the bottom of the first-level floor? I would run it between the floor joists and seal all gaps in that fitted area with foam and Tyvek tape - basically, a 96" floor to ceiling run right up past the internal foundation wall with cutouts to accommodate joists. The reason for this is two-fold: 1) it's more straightforward, i.e. I don't have to work around utilities to get back into the joist area; 2) I have this design approved by the building inspector, because it shows a *continuous* vapor retarder (the foam has a perm rating of 1.0 per inch). The cold joist is still protected from the warm air I will create in the basement space in winter, but there would be a 12" pocket between the joist and the edge of the foam (which I can stuff with existing fiberglass). Thoughts?
Works for me if it works for you.
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