Insulate/seal rim joist/sill plate
KyleH
| Posted in Energy, Heating & Insulation on
Yet another “How do I insulate…” from a rookie DIY’er! I’ve done a search but haven’t found a defintive answer. As winter is approaching, I’m wondering what the best approach to insulating and sealing the sill plate/rim joist area of my basement. I was going to use low expanding spray foam to seal the gaps between basement wall/sill plate/rim joist, then use rolls of fiberglass insulation against the rim joist. Is this the wrong approach, are their better materials to use?
Thanks for any help.
Kyle
Replies
Your ideas are good. You could even use a "normal" expanding foam if you want. The extra expansion won't push anything apart. But I don't know that it has any significant advantages either.
Unless you're the lead dog, the view just never changes.
I'd skip the fiberglass in favor of a couple of inches of eps foam - the white beadboard stuff. Cut it to fit loosely between the joists, and fill around it with low expanding foam. Take a look at the cheap foam gun at http://www.efi.org. Ideal for a homeowner weatherizing one house.
Andy Engel
Senior editor, Fine Woodworking magazine
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By eps foam, you mean the white 'styrofoam' that is used in packaging around electronics, etc.? Could you also use the 'blue foam'?
Thanks for the EFI link. Any benefit in splurging for the gun vs. just using the spray cans?
I'd recommend against the blue, xps foam as it's a vapor barrier. Yes, there is a benefit to the gun. Get the cheap one - it's around $40. One can of foam for it costs about $18, and contains 7 times the volume of the stuff in hardware stores. Also, the gun allows a precise application that's not possible with foam in a can.Andy Engel
Senior editor, Fine Woodworking magazine
An updated profile is a happy profile.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
None of this matters in geological time.
Great, thank you Andy. I'll look into the gun, and try to find the white foam. Is that something I can find at the local big box stores?
you can also do it this way, plastic vapour barrier folds and creases very easly ..
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sleeps till noon but before it's dark...
Sometimes. I buy it at a local insulation distributor, though. And if you can't find it, the blue or pink foam is probably OK.
Andy Engel
Senior editor, Fine Woodworking magazine
An updated profile is a happy profile.
Other people can talk about how to expand the destiny of mankind. I just want to talk about how to fix a motorcycle. I think that what I have to say has more lasting value. --Robert M. Pirsig
None of this matters in geological time.
Kyle,
You might want to check with your local spray foam insulation contractors. My insulation guy bid me about a buck a line foot to insulate my rim joist with spray foam. I ended up doing mine with bats as I still had a bunch of structured wiring to do in spots but needed to have the insulation in for final inspection. I may still pull out the fiberglass and have them come spray it.
Regards,
Dennis
By all means go with sprayed-in urethane foam. This is one area where you not only want the insulation, but the total airseal that only foam can do.
I just went throught that last winter I got a foam insulator to come and spray for me, the cost of those foam kits won't save you a dollar to do it yourself. Maybee a little more conventient not having to let someone into your house. But they are way faseter and you probably actually end up getting more foam in your house. Keep in mind there is an r-3.5 inch foam and an r 6.5 the latter is much more expensive going around your joists with roxul wouldn't be to hard. Bugs and mice don't like it where as they tend to accumulate in pink
I thought most foam contractors charged a set-up fee meaning that even a relatively small job would still cost close to a grand...
Someone above I think said something about 1$ a liniar foot for strayed foam, so say for a 40 x 40 house would be $160 to do the rim joist. It's hard to believe that a guy with a spray foam rig would even pull into your driveway for that amount...
How about telling us the actual price for what you purchased, the number of square feet you got foamed, and the type of foam?
This goes back a ways, but I payed 650 cdn. It covered my rimjoists in my basement and my kneewalls and attic spaces in my home, as well as a bathroom adition. I'm sorry I can't remember what the cubic footage of all this was. I had the guy over one afternoon and he said his guys had a half day somewhere else and on the way back the would get me. It was the 'icy' foam or something like that not the super hard stuff. This has to be kept dry and it's soft so rodents could still burrow and only R.3 an inch
If you can afford the foam and don't want to get into the act and dirt around old sills, have the foamers do it.
If you want to do it low cost for yourself (and are of Scottish decent like myself) and have/can purchase some scrap/cheap fiberglass/foam from a re-cycler, here's what I'd do:
Install cut to size fiberglass in the joist cavity. Have 2-3 inches thicker than you need. Cut the foam board (not white beadboard- not considered full air barrier material) just the size of the cavity opening or 1/16" larger. Push board in under fiberglass is compressed and board is jammed in place, caulk edges to com-lete air seal.
Don't worry about compressing the glass; for its listed thickness, the R value drops but the R/inch in the cavitygoes up. Did a calculation of this on another thread the other day. Was a 36% compression of an R19 batt for 2x6 walls in a 2x4 wall- the final R per inch was 4.3, up from the standard 3.4-3.5. The old Glasclad for under siding we used to have here in Canada had a 4.4 R/inch.