Ice dams. What you need to know about your roof.

I had my upper roof insulated last year (new baffles, blown-in insulation) and the roof over my sunroom addition insulated about six months ago, also with blown-in cellulose. Imagine my surprise to wake up last week and find this.

leak 2

Those two inch holes are where the insulation was blown in; I hadn’t got around to plastering them. As soon as I realized I had sprung a leak, I punched through them so the water could drain out. I also tore off the drywall because it had a giant bulge in it (about two  cups of water poured out the moment I did).

I set up my bucket to catch the drips and then I went outside to try to figure out what was going on. And here’s what I found:

leak 3

Now, after the roof was insulated, I realized we’d forgotten to insulate the little tin roof over the bay window and I had arranged for Cedric Poon, a local contractor, to come and do that for me, but he was booked until March 10.

I thought I had time; after all, we hadn’t had much snow. Clearly I didn’t.

Water  melted from the sunroom roof above it and froze when it hit the cold tin roof, then built up until it blocked the eavestroughs and backed up under the shingles. The entry point of the leak on the inside of the house matches up perfectly to the ice you see on the outside.

But that wasn’t the source of the problem, I discovered, it simply added to it. It turns out that while I have two roof vents on my upper roof, one was completely blocked by snow. Both are too small for the space: the current vents are only capable of venting 70 sq ft each.

leak 4The heat in the attic of the upper level had nowhere to go so it was melting the snow on the roof and turning it into icicles which were then dripping  onto the sunroom roof and running down,  and freezing when they hit the ice dam.

Bernie Lauzon of Lauzon Roofing came by today to remove the ice and  prevent any further damage. ($ 100 plus taxes and that ice is gone.)

As soon as the snow is gone too, we will install new, appropriately-sized vents, replacing the existing ones on the upper roof with bigger ones and installing a new one in the sunroom roof.

Meanwhile, Aucoins Insulation will come back to remove the wet insulation and install dry stuff. My drywallers and painters (Dave and Jeff Smart of Smartchoice Painting) are going to fix the damage once they’re all done and it will be as good as new. I’m lucky to have great trades to respond so quickly but here are the  two lessons I’ve learned about ice dams.

First of all, adding insulation alone isn’t enough; you need vents that are the right size for your attic. Secondly, don’t forget about insulating things like bay windows. That little roof needed insulation too. In the next week or so, it will get it.

A huge thanks to Cedric Poon, Dave and Jeff Smart, and Jake Morgan, all of whom came by at various times to remove snow, cut channels into the ice build up, and help me out on short notice. I’m lucky; the damage is minimal.Oh, and the cost of new Venmar vents? About $ 100 each for the vents, around $ 250 each, installed. Well worth it.



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