I’m going to eventually blow cellulose into the attic, so I need to install insulation dams between rafters. The house is brick faced, so not only do I not want to block the eave vents, I also don’t want to fill the gap between wood wall and brick.
Since I often take the “long way ’round the barn” when doing stuff like this, I thought I’d throw this out here and see if someone had a better method.
The current thought: From scrap ply, cut a piece to fit between the rafters with a notch removed to slide a styrofoam chute into. The styrofoam gets stapled to the underside of the roof sheathing and the ply bridges the vertical space from the top plate. Then foam-gun all the seams. (the two screws in the pic are just so I can hold on to the ply).
Firstly, I’m not sure this is the fastest way to dam. Secondly, if I want to make the ply vertical, I’d need to attach blocks to the rafters to attach the ply to. Without the blocks, the ply would simply be set on the top plate and leaned against the foam, but I’m not sure that is secure enough.
Ideas?
jt8
“Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree.” — Dr. Martin Luther King, Jr.
Replies
What I did was use a bunch of corrugated plastic political signs that were two feet on the narrow dimension. Stapled each to two 1x2s on edge, placed about 1 inch from each side, with a short piece of 1x2 at the "business" end to hold the spacing. The 1x2s projected about 8" beyond the end of the signboard, and another narrow piece of signboard was attached to this.
These were installed by sliding the "business" end into the eave, with the 1x2s up, then lifting the other ends of the 1x2s up even with the rafters and tack screwing them to the rafters. The sign board then ended up wedged against the rafters, and the narrow piece was wedged against the top plate.
One nice thing about this scheme is that you didn't have to get any closer than about 4 feet to the wall/roof corner, making it feasible to do in my 4/12 attic.
But this was a truss roof, where the joists weren't in the way as they are in your case. But maybe the above will give you an idea or two.
Re your current scheme, I'd suggest maybe using a piece of rubber foam (available from a fabric store) instead of the plywood piece. If you go with the plywood (or maybe use sign board), attach wedges to it so it can be jammed into place. (In fact, a piece of corrugated sign board, cut to your profile but 2" wider, with the sides folded back at about the 1.5" line, should jam into the gap nicely. A piece of 1x2 or plywood could be tacked across the piece to keep it from folding in the middle and provide a place to push.)
I don't think there's any need to foam the cracks -- not much is going to get through a gap smaller than 1/4" or so.
"I thought I'd throw this out here and see if someone had a better method."
Yeah, you buy this item that is designed by the same company for that very purpose: http://www.adoproducts.com/wind.html
Also, are you sure you bought the correct width? When I did mine, they fit a lot tighter from side-side.
"I never met a man who didn't owe somebody something."
Also, are you sure you bought the correct width? When I did mine, they fit a lot tighter from side-side.
You're looking at one half of one of these:
View Image
A whole one didn't fit between the rafters.
Sounds like I need to try and make a special trip over to ABC, because my Lowes don't have the vertical pieces or a better fit.
jt8
"Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree." -- Dr. Martin Luther King, Jr.
Yeah, that's what I used but they sold them in 2 sizes for 16" or 24" rafters.
"I never met a man who didn't owe somebody something."
Your way looks like a painfully slow way to do things! Ouch!
Our rafters were 16 O.C. and Menard's had 16" plastic baffles like what is shown mid-page here:
http://www.lowes.com/lowes/lkn?action=howTo&p=Improve/InsulHome2.html&rn=RightNavFiles/rightNavHeatingCooling%20
Being thin plastic, they are flexible and bendable. Placing them against the roof deck in approximate position, the bottom end was easily curved downward and back allowing it to be stapled to the top of the 2x wall plate. Then the rest of the baffle was stapled to the roof deck and adjacent rafter sides. This way the insulation side of the attic was closed off from the eave and cellulose could be blown right out to the edge of the wall. Other than the price of each baffle (a ripoff IMO) this was a fast way to take care of this issue, so I had my sons do every rafter cavity.
Instead of scrap ply, use 1/2" "Tuff-R" insulation panels or similar stuff. Much easier to cut. Glue them in place and seal the gaps with caulking compound or "Great Stuff" foam. You could use that one plywood panel you made as a template for cutting these.
I've used squares of unfaced fiberglass batts folded in half, with the folded edge facing out. Push it in just far enough and let friction hold it in place. Fills all the gaps nicely (there'd be less gaps to fill if you used 16" rafter vents rather than a 24" split in half).
I bought some of these to do my attic. Haven't got around to installing them yet, figure it will be a good fall season project for me.
Hope this helps,
Kenny
I only see one size. Do those break down to accomodate a 16" on center rafter instead of the wider span truss?
jt8
"Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree." -- Dr. Martin Luther King, Jr.
Yes, they do break down for different widths. That's one of the reasons I bought these, the original part of my home is rafters, the addition is trusses.Hope this helps,
Kenny
Edited 8/7/2007 11:31 pm by 1hotwire
Whats wrong with plain old wax coated cardboard insulation stops in this application???