Don’t make these three basement nishing mistakes
Finishing your basement is the most economical way to add comfortable living space to your home
Winter is the season when Canadians most cherish the idea of a nished basement. Sure, it’s great to have one any time, but as the winds swirl and snow blows outside, there’s something especially attractive about snuggling into a comfy couch or easy chair in your warm, bright, inviting subterranean space.
e thing is, most homeowners and some professional builders don’t realize how easy it is to nish a basement incorrectly. Even if things look great on the surface, common design mistakes can encourage mould, mildew and hidden corruption behind the scenes in your basement — none of which can be xed easily after the fact. is is why the best way to nish a basement is to do it differently than the way it’s always been done.
The primary challenge when it comes to nishing a basement is maintaining good indoor air quality throughout your home. Comfort, sufficient light and a pleasant oor plan are all important, but they don’t matter much if your basement is polluting your indoor air with mould spores. e unique danger with basements is that moisture in the form of liquid water leaks, moisture vapour and condensation will enter wall cavities and oors, triggering the growth of mould and mildew on organic materials. A well nished basement is always dry, but also has some capability to handle unexpected moisture.
Basement Finishing Mistake #1: Having Too Much Hope
Even the wettest basements in the world look dry at some times of the year. And even the smallest amount of leaked water will have disastrous effects if it happens behind a wood frame stud wall or into the pile of broadloom. All this is why it makes sense to hold your basement nishing enthusiasm in check and give yourself a chance to prove for sure that your basement really is dry. It’ll cost tens of thousands of dollars to nish your basement in even the simplest way, and this is a signi cant risk if you go ahead without monitoring that your basement is truly dry over at least one full year before nishing.
Basement Finishing Mistake #2: Installing Carpet on Concrete
Even with the addition of thick underlay, wall-to-wall carpet on concrete basement oors is bad for two reasons. First, if you have any kind of a leak — no matter how small — it’s going to soak the carpet and kickstart mould. And second, carpet can encourage droplets of condensation to develop along the concrete oor during warm, humid summertime weather. Both these problems can be solved with the right kind of subfloor underneath whatever nished oor you choose. Every building supply store sells basement subfloor tiles these days. They create a slightly elevated space underneath to separate nishing oor from concrete and create a small drainage channel underneath in the event of a small water leak.
Basement Finishing Mistake #3: Inappropriate Rim
Rim joists are the areas where the oor frame of the rst oor of your house meets the outside walls in the ceiling of your basement. Almost every home I examine has mould growth on the bre-based insulation behind vapour barrier plastic installed in rim joist areas. As common and code-compliant an approach as this is, it simply doesn’t work. e code de nitely needs to be upgraded. ere’s simply no way you can install plastic to seal out the warm, moist indoor air from infiltrating the fibre insulation, cooling within it during winter, and forming mould-promoting liquid water droplets inside. At least a three-inch depth of closed cell spray foam is the only way to seal and insulate rim joist areas properly.
Finishing your basement is the most economical way to add comfortable living space to your home. You’ve already got a roof and exterior walls, you just need to divide up the basement and make it nice. Just be sure to do it so mould doesn’t get a chance.
Steve Maxwell hates indoor mold in all its forms. Visit Canada’s largest collection of how-to and home improvement articles and videos at Baileylineroad.com House Works by Canada’s Handiest Man’ Steve Maxwell features DIY tips, how-to videos and tool product reviews. Feel free to say send him an email to say hello or to ask
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A beautiful nished basement is a great home feature, but enduring success depends on avoiding speci c common mistakes that promote mold and harmful indoor air quality.
This basement allows no organic matter to touch masonry walls or oors. When this strategy is applied to a truly dry basement, the result is long-lasting freshness and freedom from mold.