Nobody wants a cold, moldy finished basement, but that’s exactly what many homeowners get after they’ve spend tens of thousands of dollars finishing their basements. Why? Failure to recognize three key Canadian basement finishing facts. Even a surprising number of contractors don’t take these seriously enough:
Fact#1: Never install carpet directly on concrete.
Failure to take this fact seriously won’t absolutely guarantee your basement will smell musty in time, but it is a really good start. And make no mistake. If your basement smells musty it means air quality in your entire home is lower than it should be. Even underpad between the carpet and concrete floor won’t eliminate the risk, and the determination of air is the reason why.
Neither carpet nor underlay can stop the downward movement of basement air towards the underlying concrete floor. And if that basement air is warm enough and humid enough (as it often is during summer), it will lose some of its moisture as it sinks into the carpet pile, cooling as it gets closer to cool concrete and leaving droplets behind.
The solution? Install a basement subfloor that’s also made to act as a vapour barrier. The most widely available subfloor tiles in Canada come from a company called DRICORE, and they make a big difference in the finished project. Effective basement subfloors stops basement air from getting near the concrete floor, keeping that air warmer and condensation-free. Click here to learn more about basement subfloor installation with my detailed online basement finishing course. It’s for people wanting to do the work themselves or hire a contractor intelligently. This course is free until October 2020.
Fact#2: You need cold air return ducts.
Most Canadian homes have forced air heating systems, and the furnaces behind these systems are usually more than powerful enough to heat basements comfortably after finishing. The reason too many finished basements in this country are not warm enough in winter is because the furnace never has a chance to warm the cool basement air. Improper cold air return ducts are the reason why.
Forced air furnaces operate by heating air, distributing it around your house, then drawing that same air back into the system for reheating. And while it’s not always convenient to extend cold air return ducts down to the basement floor, that is what’s necessary for proper basement heating. Without floor-level cold air returns ducts near the floor, pockets of lukewarm air will remain in your basement, never able to gain enough heat no matter how hot you make the rest of the house.
Fact#3: Let your basement prove it’s bet-your-life dry.
Enthusiasm is probably one motivation behind your basement finishing plans, but enthusiasm can also lead you into a nightmare if it’s not tempered with good old boring common sense. What does this mean for basement finishing? Never finish a basement without at least one year of absolutely dry performance in all seasons. And to be honest, you could still have a leaky basement several years out, when an exceptionally wet season happens. The issue with leaks is vital because even a little leaked water can trigger a lot of irreparable mold growth and the poor indoor air quality this creates.
Take these facts seriously and you’ll be that much more likely to enjoy mold-free performance from your finished basement spaces.
Steve Maxwell and his wife Mary live on a 90-acre modern homestead on Manitoulin Island, Ontario in a stone house they built with local materials beginning in 1985. Steve is Canada’s longest-running home improvement and how-to columnist and editor of Home and Property. He divides his time working on the land, building things large and small, and creating articles and how-to videos that teach sustainable, self-reliant, hands-on living skills. Steve’s website, Bay Line Road, is named after the rural road where he and Mary live with their five kids.