Finishing the Basement

In the event I ever get around to becoming a university professor, I’ve got my first research topic chosen: Basements, Potatoes and the Canadian Psyche. It springs from a theory I have, one that I’ll test after my seven-figure research grant comes in from the Ministry of Architecture and Root Crops. I contend that Canadians have basements today because of a throw-back to the era when each household required a frost-proof root cellar for winter-stored potatoes, carrots and turnips. Look to warmer parts of the globe and you don’t often find basements under anything. And that fact has something to teach us Canadians about basement renovations. It doesn’t matter that most of us can now buy potatoes any day of the year. Tradition has a long arm. For most Canadians, a house is not quite a home without a basement. So in one sense, even modern, finished basements are still used to store potatoes. Nowadays, any worthwhile basement potato bin needs wall-to-wall carpeting, a big-screen TV, and a plush couch for the two-legged potatoes that lounge in front of it. If you’re planning to finish your basement, then it’s always wise to keep in mind what you’re really up against: the conversion of a hole in the ground into a warm, dry, bright living space. And this fact exerts more influence on the nuts-and-bolts of a successful basement reno than anything else.

Foot-Friendly Floor
A reliably-dry space is the essential starting point for any basement finishing project. Don’t even think about starting without that. But even given this much, a typical bare basement floor is everything most of us hate underfoot: it’s cold, hard and ugly. That’s why so many homeowners choose carpeting for finished basements. Just roll it out and you’re done. But used alone, or even with an under pad, carpet is a risky proposition below grade. And the source of this risk is invisible moisture. Even apparently-dry basements can develop moisture problems during humid weather, when condensation occurs on cool floor surfaces. That’s why you need to consider some floor insulation strategy upfront. Carpet alone isn’t good enough because warm, moist air percolates through the fibers and condenses at the bottom of the pile. And too often this process is enough to make it smell like you’re living with a wet dog. Basements don’t have a musty reputation for nothing. There are two approaches I favour for basement floor prep. The one that offers maximum insulating value starts with a layer of 1 1/2 or 2-inch thick extruded polystyrene foam placed against the concrete, with a layer of 5/8-inch plywood on top. The whole thing is secured with Tapcon screws torqued directly into pre-drilled holes in the concrete floor. You get a warm, dry, all-wood subfloor that’s ready to take almost any kind of finished flooring safely, including carpet.

Your home may feature every basement waterproofing strategy known to mankind, but there’s still no guarantee that, say, a week of torrential downpours won’t overwhelm your bulwarks. And if this possibility concerns you, consider a second type of basement floor strategy. It uses a new type of product made of interlocking tiles of water-resistant wafer board, bonded to a dimpled plastic layer. This plastic separates the wood from the concrete floor, while preserving small drainage channels between the two. You certainly don’t ever want water to trickle into the space under the floor, but if it does there’s no disaster. There’s still a clear path to the floor drain. Sublfor is one brand that I’ve tested and like. Even when submerged underwater for three days, the wafer board substrate remained solid, with minimal swelling.

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