another old house/insulation/moisture si
A friend is buying a neat old house, has a situation, and I need to refresh my thinking. Been into the archives, but need more. I’m not doing the work, but would like to know what the best practice is.
The house is about 120 years old, framed with biggish old timbers probably by a shipwright (irregular bays)…..stands on a point looking out to a bay here in Cape Breton, Nova Scotia….water all around, and it will get the full Atlantic storms.
The house has clapboards, but they are already coming off on one wall. The plan is to remove them all on each wall, insulate (no insulation at present), sheathe, and shingle. Interior finish is painted pine boards, handplaned….has the gaps you would expect, so no chance of a continuous coating for a vapour barrier. That stuff isn’t coming off.
In this situation, what insulation would you choose….what about vapour barrier…..what’s best on the outside (I’m thinking felt). I see kraft or foil faced fibreglass suggested a lot, but I don’t even know if that is still available in Canada: I’ve never seen it except in older homes.
Anyway, thanks for any suggestions. Just pondering at this point.
Replies
My house had failing siding and board sheathing with huge gaps, plaster interior walls that were staying, so i had essentially the same ingredients as your friend.
I removed the boards, used 7/16 OSB sheathing, drilled a 2-1/2 hole in each cavity, and dense-packed cells in the walls. We (you need two people, one to fill the hopper of the machine and one to wield the hose) used the machine for one looong day.
I don't know if you have HD/Lowe's or anything like that up there, but if i buy my bales of cellulose at the store, the machine rental is gratis. Also, you don't need a vapor barrier. You can use the same machine to spray loose fill in the attic too, though probably that'll be a second trip after the wiring's re-done. <G>
The only solution that would have been better would have been foam sprayed inside the bays before re-sheathing, which would have the advantage in a high wind area on the coast of gluing all the partz together, but it's ghastly more expensive and not a DIY thing. I also didn't feel comfortable removing all the sheathing at once in order to do it all in one trip for the contractors. You don't need a vapor barrier for this either.
If the interior walls are that leaky that cels or foam would leak to the interior, a layer of 1/2 foam cut to fit the bay with the cells or foam sprayed against it will keep the inside clean.
Another labor-intensive solution I used when i was doing one small area at a time was cut foamboard slightly smaller than the size of the bay, wedge it in place, then use spray foam in cans to seal between foam and the stud. You don't have to rent any machinery, but the foamboard ain't cheap and it IS slow going if you have to cut 2 or 3 layers of 2" foam for each cavity.
There's also blown-in-blanket, but i have no direct experience with it.
I can't remember exactly what my costs were for insulating my walls, but as i recall, the foam, contractor-installed, was going to cost 5X what the cels cost me to buy. It was easy, suited my plan to re-sheathe one wall at a time, and less than $500 for materials and doesn't require a vapor barrier. I had occasion to remove the a couple areas of interior plaster where i'd insulated and i was impressed how well-packed the bay was. I've been really happy with the results and my heating bill, esp since NG isn't an option.
I also used a layer of 1/2" foamboard over the new sheathing as a thermal break, which i highly recommend for us northerners as long as it's not a huge pain to re-detail the openings for increased wall thickness. Then you may as well do a rain screen...
I basically agree.But I would like to see something "seal" the inside walls. Both to keep foam or cells from comeing through also also for a bondbreaker so that the inside walls could be removed if/when needed.But I am not sure what to use. Insulmesh? Tyveck? Sheet foam cut and foamed in place would work, but be a lot of work..
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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 mentioned a sheet of 1/2" foam to prevent the cells escaping inside (though i forgot the inch mark). I would worry than anything you didn't positively seal, like a fold in visqueen, could provide small air channels, channeling moist air through the wall. I guess it could be done tidily, taped in place... It's not necessary in my experience to worry about dense-pack falling after installation if you have to remove an interior wall. I did that in a few spots to move doorways, etc. and it just stood there, intact, no "bond" to break. Not like loose-fill at all, LOL...
Edited 8/11/2007 4:01 pm by splintergroupie
Thanks for the comments guys. My buddy is working it our with his contractor.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
I think I'd tack in felt (probably secured with lath) and then foam. The color of the felt shouldn't show too badly through the cracks. Use a good rain shield on the outside.