So, after last year’s ice dams, I’m working to try and avoid them with pre-emptive actions to take care of the problems. Some of these will be inside the house, and others outside.
Inside, one of the things I need to do is empty the four rafter cavities that are over our son’s bedroom closet (below the attic floor) of the blown-in insulation, and try to use some rigid poly insulation that will allow air to come up from the eaves under the roof. This will go along with replacing the plaster and lathe with drywall, to take care of the water damage we had there.
The other thing I need to do is patch the places where the previous owner had the ‘master’ bathroom replaced. In order to run some electrical wires, the contractors they used put a big hole in the back corner of the plaster of the room, which they covered with a soffit over the shower. The thing about this hole, and the hole I assume is at the bottom of the wall, is that warm air from the house goes right up behind the shower and up under the base of the valley on the back of the house where we had the worst ice build-up. I’m still debating the best way to fix this problem, either from the attic above, or from getting into the soffit from the bathroom.
Outside, I’ve worked up a plan to run heating tape/wire along the eaves, gutters, and valleys where we had problems (and in the front where we also get ice build-up). This involves running wire to outlets to the exterior in the areas the tape will be located, and installing GFI plugs in these. Luckily, the finished room in the attic contained a 20amp, 240 outlet which we never used. I say luckily, as it was wired incorrectly for a 240 outlet (no return line other than the ground!), but after disconnecting it in the breaker box, it was a nice dedicated 12 gauge 110 line available in the attic, with enough extra line up there to install a junction box.
From the junction box, I need to run two lines, one to behind the valley over the shower, and the other to the front of the house. Each of these will be placed under the eaves of the roof, which will allow for the plugs to be protected from the weather, and to give a ‘drip loop’ to the wires which will insure that if water IS running down the wire, the lowest point of the wire will be below the plug/outlet.
The back area has two problem spots, and covers 137 feet of eaves, three valleys, a skylight, a small 4’x4′ first-story roof, and three downspouts. The eaves come out about 16-18” and have a split-slope, where the two feet of roof closes to the eaves is a more gentle slope than the rest of the roof. In dealing with that, I planned for 24-28” of coverage of the eaves, full gutter coverage, and six feet (or so) of coverage up the valleys with the heat tape/wire.
Frost King has a formula for figuring out how long of a wire you need for your task, and a couple of minutes of work made it an easy spreadsheet. Not surprisingly, I needed more than one length of wire for this set-up. Frost King offers wire lengths from 250′ to 50′, so I ended up with a combination of one 200′ length and two 60′ lengths, with one 60′ length dedicated to most of the gutters and two downspouts, the other 60′ length dedicated to the short section of roof (over our son’s closet), one of the valleys, the rest of the gutter and the last downspout, and the 200′ length to cover the rest of the eaves, the skylight and the other two valleys.
In the front, there is only one little section of eaves, and a long, winding gutter with a feed from the first story roof over the entryway, so a 60′ length will take care of the area, with a loop making sure the entryway roof outflow is clear. And all of these will need the self-regulating, temperature sensitive plugs so that they’re only on when they need to be.
(Actual installation information in Part II)