OK, finally got the chutes installed, bypasses sealed, etc. Ready to upgrade the insulation (generously speaking, 6″ of cellulose) in my attic. So what would be the recommendation for depth (assuming more cellulose)?
This is southern Minnesota (zip 55920), 1976 house, conventional construction for that period (though tightened considerably from the original), trussed roof, 4:12 pitch, good ventillation (tripled from original), approx 1000 sq ft footprint.
Seven blunders of the world that lead to violence: wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, worship without sacrifice, politics without principle. –Mahatma Gandhi
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I would install to a total minimum depth of 16" with cellulose. (R=50+)
Any kneewalls or other difficult framing?
Garett
No kneewalls. Standard low (non "energy") truss that goes to 3.5" at the eaves.
Seven blunders of the world that lead to violence: wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, worship without sacrifice, politics without principle. --Mahatma Gandhi
With your existing 6" of insulation I would guess you already have baffles at the eave.I like to make baffles out of 1 1/2" foam board when I run into low heal heights. It is a pain in the arse to install baffles after the fact but it can be done. Use a couple scraps of plywood long enough to lye on and scoot your way along.I have never tried but it seems that you would better R value by slipping the foam in under the insulation too. EXP foam would not be a vapor barrier if that is a problem.Garett
I've got the baffles covered (so to speak). I had previously tripled the number of vents over the original, so more baffles were needed, and the existing ones were't long enough for the depth of cells we're talking about, so they needed to be extended.Came up with the idea of taking two 7-foot 1x2s (8-foot is too long to handle), spaced about 22" apart, and tacking old 2x3-foot political signs to them, leaving about 8" of the 1x2s sticking out on the one end (and the rest of the 7 feet on the other). Slide the 8-inch stubs into the gap above the wallsn (with the signs down) and then lift the near ends up and tack them to the rafters, producing a vent area the full 3.5x22.5 inches in size. The same deal was used to extend the old baffles.For the ends (not full width) and one in the middle that was partly blocked by a plumbing vent, I cobbled corrugated metal duct to a register adapter, stuck the whole thing on a stick like I was going to the State Fair, and shoved it into place. Stick is then tacked to a rafter.This allowed me to do all the baffles from the center, never having to do more than squat down a bit.(In case anyone is wondering, I did a quickie flammability test on the signs. They burn, but no more rapidly than a piece of a commercial chute. If I were doing this professionally, though, I'd look for a fire-retardant material.)
Seven blunders of the world that lead to violence: wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, worship without sacrifice, politics without principle. --Mahatma Gandhi
OK, have an estimate. Works out to about 880 cubic feet of cells, guy thinks he can do it in under two hours. Price is $950. How bad a rip-off is that? (This is a non-union area, but labor prices aren't super low, though I can't quote any typical hourlys.) If it's not too bad I'll probably go with it, vs muck around with another quote. Most outfits here don't want to blow cells.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
Dan,It's a little higher than around here but...It's your choice. You already did the baffle work why not do it yourself? It would probably take you the better part of a day with a rental machine, plus the time to pick it up and return. Our attic blower will do about 85 bags an hour so your attic would take 2 - 2 1/2 hours including set up if we could park close, Add an additional 1/2 hour reload the trailer with bags plus travel time and expense. Your looking at a half day with 2 guys and equipment. Fair? It depends on what your time is worth?Good luck on the project,Garett
The guy told my wife that he could do it in under two hours. I don't know what he was including in that, but it's definitely an uncomplicated blow, other than the need to fill under a catwalk.
It's probably worth $300-400 to me to not do it myself, in part to keep peace with my wife, since I won't be able to get it done right away.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
r50 sounds good and not overboard... so blow to 20" settle to 16"
cordon it off and figure your bales per cordon so you can tell if you are getting the coverage you designed forMike Smith Rhode Island : Design / Build / Repair / Restore