Cottage Q&A
QUESTION
I've been told that opening a lightly insulated or uninsulated cottage and heating it for brief winter
escapes can be damaging to drywall or insulation. Is this true? How can we prevent potential problems?
ANSWER
Your info is right on target. Typically, the first thing cottagers do on a winter visit is crank up the heat or get a good blaze going in the woodstove to warm the place up. Next, we set about enjoying ourselves - heading outside to play in the snow (and tramping some of it back indoors). Cooking, showering, breathing in and out. In other words, loading up the air with moisture.
Then we turn off the heat and leave, and that's when trouble can start. Cold air can't hold as much moisture as warm air, so the moisture condenses out, especially where it meets cold surfaces. If you were there to watch, you'd see it forming on places like single-pane windows, doors, and even on the inside faces of exterior walls, says Andy Christie of Safe Homes Canada Home Inspection in Barrie. That's also where damage is likely to show up first: water-stained window and door mouldings and mildewy drywall. If this scenario is repeated often enough, it could eventually cause structural damage as well, rotting out floor sills and the bases of wall studs. Damage to existing insulation is unlikely, Christie says. In fact, if it's practical, adding more insulation and a continuous vapour barrier should lessen the condensation problem, by moderating the abrupt temperature difference between inside and outside and preventing moisture from entering the wall cavity.
But if you're only visiting the cottage a couple of weekends per winter, there's another way to clear out moisture, suggests André Robichaud, eastern Ontario district manager for Canada Mortgage and Housing Corporation. Once the heat's off, and while you're packing up to leave, open up all the doors and windows. In 20 minutes or so, the air inside should be as dry and cold as the air outside, so condensation damage can't get started.
In the final analysis, warns Christie, cottagers should expect to carry out minor repairs periodically to interior finishes and drywall in any cottage that's uninsulated or lightly insulated. Even the sun's heat will create cycles of warming and cooling that will produce some condensation indoors. The only way to solve the problem completely is to insulate and seal, and keep the heat on at a low level year-round.
* Published in the November/December 2005 issue of Cottage
Life
