ice on house

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Barry J

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Yeah, "rock salt" is a no-no,,,that can also stain your shingles...that's why you use calcium choride
 

Dana

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here are some pics of the ice on my house, attic insulation above the bathroom, and the ice dam

The middle picture shows mold/rot where the wood has gotten wet- this is clearly not a recent phenomenon, and is likely to be air &/or heat leaks through that below code-minimum fiberglass in the attic. (Cookie has it right- whether they sealed & insulated the wall properly or not, you DEFINITELY need more insulation!)

Keep the the soffit & ridge ventilation scheme using soffit chutes, and add at least 6" (R20+) of blown celluose over the fiberlgass. Using R19 batts would help, but not half as much as blown cellulose for tow reasons: Batts cannot fill in the compressions and voids in the original insulation, whereas blown goods inherently will, then, low-density fiberglass allows too much convection in a cold-side up horizontal application and performs to a much lower R when you need it the most- R38 fiberglass performs closer to R20 in an attic app when it's below zero, as it has been recently.

With a cellulose overblow you restore the R value of the original insulation- no need to remove it. If you put up some cardboard strips as depth guages (staple them to the joists), an mark them 15" up from the ceiling sheet-rock below, then fill in to a level smooth even depth you'll be hitting around R50, which is above code minimum, but still cost-effective in a MA climate, and far more likely to fix the ice-damming and shower condesation issues than going code-minimum with batts. You can probably even get 3/4 of it payed for through a MassSave weatherization subsity, which would be less than the cost of the material as a DIY. Whether contracted out or DIY, use borate-only /sufate-free material (most of the stuff at box stores have sulfates, which can be corrosive to metals when wet). If contractor, go with a "stabilized forumla" that contains water-activated adhesives that will dramatically reduce settling and redistribution of the material by high winds whistling through the soffits. If DIY, and in a high-wend location, use a dry-blown borate-only, and use a garden sprayer to lightly dampen the top surface near your soffit chutes, which will cause it to crust over making it wind-resistant. (In MA National Fiber of Belchertown distributes their borate-only "Cel-Pak" dry blown material through Kamco, which caters primarily to contractors, but you'd have to rent a blower elsewhere.)

The top plate of the strucutral studwall (clearly visible in the middle pic) won't be adequately insulated if you just jam some thin chutes in there and blow. It's probably worth a cut'n'cobble on 2 layers of 2" XPS rigid-board, or better yet, use 3-4" EPS bead-board to make the chutes, leaving 1.5-2" of clearance between the EPS and roof deck. (You can buy recycled EPS for wicked-cheap at the Insulation Depot in Framingham, if you do the pick up- they won't deliver in less than tractor-trailer load quantities, but they'll sell in small quantity out of the yard.) Cut to a loose fit, and 1-part foam to air seal it at the rafters and top plate, and try to get the angle right where it meets the top plate.) If you have a contractor doing it, just going with 4" of closed-cell spray polyurethane foam on the top plates would be less labor, and higher R where it counts the most, just make sure they don't seal the soffit ventilation in the process. (4" of mid-density closed-cell Icycnene would be cheaper than generic SPF- slighly less R, but still enough.)
 
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