Basement renovations: Traditional methods can be risky

Experts from the Canada Mortgage and Housing Authority (CMHC) predict that we are entering a boom period for basement renovations. The trend is being driven by homeowners’ need for more living space. It’s a terrific opportunity for contractors that have developed good systems for basement finishing using state-of-the-art techniques.

But while the business opportunities in basement renovation work are large, so are the risks. The biggest risk of all concerns moisture. How are you going to make sure that moisture – and its inevitable consequence, mold – doesn’t wreck your client’s dream renovation and your reputation?

As “building envelope” science has progressed over the years, traditional methods of finishing basement walls and floors have come under attack.

The traditional way to renovate a basement is, of course, to use good old-fashioned stud framing, fibre insulation and a poly vapour barrier – just like you would above grade. Nothing wrong with that, right? “It’s the way we’ve always done it,” most contractors will say.

In some cases this method will work. If the contractor has a lot of expertise, specific technical knowledge and the right site conditions – plus a bit of luck – a basement finished the old-fashioned way can work out just fine. But there is a lottery factor at play.

Why? Because moisture – in the form of water vapor – is often on the move through concrete basement walls. In the summer, vapor will tend to move from the outside in, through the concrete and through the batt insulation, until it finally stops at the plastic vapour barrier with nowhere to go. There, especially if the AC is going full blast, the water vapour can condense into water droplets on the back of the vapor barrier. It can begin to pool at the bottom of that wall and begin to rot and mold the wood studs and batt insulation.

Imagine stuffing a wet, used bath towel into a plastic bag – and waiting to see what happens. This can be precisely what you are doing if you finish a client’s basement with this type of traditional structure.

Engineered wall and subfloor systems for residential basement renovations aim to defeat moisture problems like this before they can even start. The leading products in this category, DRIcore SMARTWALL panels and the DRIcore Subfloor system, allow contractors to build with proven moisture-protection technology.

DRIcore SMARTWALL panels are prefabricated, non-loadbearing wall panels that are 23.5” wide and 96” high with a tongue-and-groove system to interlock the panels together. Vertical and horizontal channels allow for electrical conduit. The panels are insulated with EPS foam (polystyrene) which fills the void entirely, factory-bonded to ½-inch drywall. SMARTWALL is designed to allow moisture to move freely back and forth by the way of its semi-permeable vapour barrier. Your walls are allowed to breathe and dry. No more wet bath towel in a plastic bag effect!

On basement floors without a moisture barrier, similar water vapour problems can occur. To prevent this, DRIcore’s Subfloor product is the correct material to use with DRIcore SMARTWALL. This subfloor is comprised of 2-foot by 2-foot tongue-and-grooved engineered tiles. Bonded to the underside of each tile is a high-density plastic layer with “feet” that provide an airspace under the subfloor to allow air to circulate to help dissipate moisture that might collect. DRIcore Subfloor tiles can be covered with floor finishes that range from laminate and hardwood, to ceramic and stone, to vinyl and carpet.

At the beginning of this article, we looked at the reason that basement renovations are experiencing such a boom. It’s about living space. Living space, moisture and mold problems do not go well together. In order to protect your client’s health and your own reputation, consider asking some tough questions about traditionally-framed walls below grade.