Rim board insulating question

[joks79]

I'm looking for some input on the best way to insulate a rim board on my addition. The basement will be finished in the long run. The floors have infloor radiant heat. The floor was constructed with I joists and the engineered rim board. What's better? Spray foam, faced batts, or unfaced batts. I read somewhere that using 2" foam cut down and then seal the edges with caulking.

Any help would be appreciated. Thanks

 

[garyl62]

IMO the best is spray foam, not the stuff in a can, but the commercial application type. Might not get you the payback though if all you're doing is the rim. Faced batts would be my second choice, cheaper and easier to do yourself. 2" foam board is only an R-10 so going with any batt would be better than that.

 

[lenny]

IMO it seems air infiltration would be the main issue between the foundation, green plate and rim joist. Ideally 2" foam for the air infiltration and than bats for thermal. Like Gary said, foam would probably cover both but at what expense? At least with conventional you can DIY and not upset foam which is permenate. Anything you do will help and keeping that air from coming in is big.

 

[ezra]

if only short term till a finished basement stuff some cheep bats in.
next yr when u Finnish basement spray it all rim walls and underside of heated floor

 

[dfattack]

you asked what's best or better...commercial/professional spray foam. I have it on my houses and I learned the rim board is one of the hardest areas to seal properly. spray foam 1 1/2" then fiberglass batts on top of that is the ticket. Same thing with your outside walls. no need to use 2" foam board then have to caulk and tape. Spray it on and you are done...

 

[wak]

I would only use foam or foam and then fiberglass. I would not use only fiberglass. Fiberglass insulation allows moisture to pass through. You run the risk of that moisture condensing on the inside of the rim.

Wak

 

[freezinbevr]

All solid responses...Spray foam is THE best because of the infiltration of all those layers of wood meeting in a spot which is impossible to get at without spraying foam on it! Extra R value with some fiberglass over that and you are golden. As a heating guy, we see the frosty rim plate all the time with just fiberglass stuffed up there. I did a project this week where the wall of the home had frost on the interior of the sheathing behind the glass and the vapor barrier. Showed the homeowner what they just bought this summer...Issues.
Brad

 

[joks79]

Thanks for all the replies. I did get a price to do 96 linear feet at $400 for 3.5" of spray foam. Is this a good price?

 

[snowchief]

seems pretty reasonable considering you'd have close to half that in materials if you bought foam board and fiberglass plus your time. On homes and add ons we do we keep the rimboard back 1.5" and put the foil wrapped 1.5" foam around whole thing on outside seems to work well.

 

[catshed]

that price seems to be in line I'm guessing that is closed cell it will be money well spent if done properly

 

[IceJam]

That's a real good price..since you can go buy a kit at menards to spray yourself for 400.00
Ive ben insulating for to long and tho I don't use a lot of spray foam I would use it in your situation with no budget involved..lol
You should understand that glass products can get wet every day and when they dry they go back to there natural state !..Foam is not the best noise absorbent but in your project no need to worry.Maybe when you go to do the basement some of this could help you out.
All the replies I've read are real good answers and ideas.

Thanks for all the replies. I did get a price to do 96 linear feet at $400 for 3.5" of spray foam. Is this a good price?