COTTAGE RETROFIT
Turning cabin into a home
TURNING A COTTAGE INTO A HOME
Q What’s the best way to boost insulation in my cottage? I’m converting the place into a four-season home, but I want to preserve the interior wooden wall finishes. Paper-covered batt insulation is in the twoby-four wall frames now, but I’m concerned because there’s no vapour barrier on the warm side of the walls.
A Your plans are similar to what other people are aiming to do these days. As a larger portion of the population heads into retirement, the cottage is looking pretty good as a year-round home. The thing is, conversions like this aren’t simple because the cold-related details required always track back to big decisions made early on about foundations, frame design and water systems. Upgrades are certainly possible, but many times they’re not ideal.
You asked specifically about existing insulation and vapour barriers and this is one area where compromise will be required.
Although adding a vapour barrier on the warm side of any wall insulated with fibre-based insulation is standard practice, you naturally don’t want to remove all of that great interior wood. To preserve that wood and boost insulation values, you’ve got a couple of options. You could certainly add rigid foam insulation to the exterior walls before new siding goes on. I’ve added two inches of extruded polystyrene foam in applications like this and it’s worked well. Exterior insulation keeps your wall cavities warmer than they’d otherwise be in winter, so you’re reducing the chance of internal wall condensation because of your lack of vapour barrier.
If you’re concerned about trapping moisture within your wall cavities because of impervious foam on the outside, you could opt for rigid sheets of breathable fibre insulation. My favourite right now is Roxul Comfortboard.
Another option involves removing all exterior siding and sheathing, removing existing batt insulation, then replacing it with spray foam. This is much more work and much more of an expense and I probably wouldn’t bother if it were my project.
If you do go for adding insulation on the outside, be sure to monitor indoor humidity levels during winter. If you’re successful in tightening up your cottage, install a heat recovery ventilator to improve air quality and keep humidity levels low. The lower the indoor humidity levels, the less likely damaging levels of condensation will occur in your walls. Levels lower than 45 per cent relative humidity are what you’re aiming for.
SEWAGE BACKUP PROTECTION
Q Is it a good idea to install a backwater valve to protect my basement from sewage backup? I live in Ottawa and I’m considering this upgrade.
A The short answer is yes. A backwater valve is a great idea for most homes connected to a municipal sewage system. It’s installed in the main outgoing sewage line from your house and it allows sewage to only flow out of your home, not back in. Depending on the design of the municipal system you’re connected to and your location relative to the height of surrounding land, a failure of the municipal system could allow thousands of gallons of raw sewage from other homes into your basement. Most often this happens in the basement where the main floor drain is located, but sewage can back up and spill out in other places, too. Many homeowner insurance packages include coverage for this sort of damage, but you’re much better off never having to make a claim like this in the first place.
Installing a backwater valve requires access to the main drain as it exits the basement floor and this usually means some work downstairs that goes beyond plumbing. But truth be told, it’s a small price to pay to prevent the kind of disaster that affects homes every year.