If you watched Episode 2 of Bryan Inc. you'll know that we ran into a few problems when we dug deeper into the basement of the Highview property. If you didn't watch, well then go visit HGTV.ca and get watching!
As the show continues to be aired on HGTV Canada, I want to add some ideas and thoughts on the problems and design decisions that we had to make through the renovation and construction of the two properties. This week, I wanted to share a little more about dealing with mouldy basements. I am learning as I go and so there's no one better to use as a resource than my husband. Here is Bryan's thoughts on dealing with a wet or leaky basement as seen in his book, Measure Twice.
Finishing a Wet or Leaky Basement.
Before you start choosing a sofa and buying a big new TV, you need to take a serious look at your foundation. If your basement smells musty, if the walls, floor or carpet feel damp, or you see efﬂorescence (whitish powder) on the walls, you've got moisture coming in. It makes no sense to finish a basement with a leaky foundation. Any area that combines moisture and organic material (such as wood or the paper covering on drywall) has the perfect conditions for mould. And when you put a bunch of dry building materials into that wet area, you’re setting yourself up for rot. It’s like having a pile of fresh food on the counter: it’s only a matter of time before it gets mouldy. (Even in an unfinished basement, I wouldn’t want to see signs of moisture: too much will weaken a concrete foundation over time.)
How does water end up inside in the first place? Sometimes it’s a natural condition known as hydrostatic pressure. As the earth around your home collects groundwater, the soil expands. This extra weight builds up and presses against the foundation floor. As the pressure builds, water can come through cracks in the walls and floor of the foundation or through the pores of the foundation itself.
You don't need hydrostatic pressure to have a wet basement. Storm water and even a garden hose could be part of the problem. Most often though, water vapour is the culprit. Moisture circulates around the house as vapour, which is created by activities such as breathing, cooking, doing laundry and showering. When warm, moist air cools, some of the moisture evaporates. That’s what’s happening when warm air hits a cold window, for example - the glass becomes coated on the inside with a layer of condensation. Even without any windows in a basement, moisture can condense on cool surfaces such as the concrete ﬂoor under carpeting or the brick or concrete block behind exterior basement walls. These damp conditions are perfect for uninvited visitors like mould, which can destroy the structural integrity of the foundation itself.
Moisture can also be caused by a problem with the weeping tile. Weeping tile is a bit of a misnomer. These are perforated tubes that sIope away from a home’s foundation, right down by the footings. Any groundwater that seeps down from the surface or percolates up from below gets led away from the foundation by gravity and the weeping tile. If water is no longer draining properly, those tubes could have become damaged or separated. Blame tree roots, soil movement, freezing and thawing or age. In older homes weeping tile is made of clay, which doesn’t last forever (these days, we use weeping tile made of plastic). A waterprooﬁng pro can inspect the condition of the weeping tile, and you may be able to have it patched, if you're lucky. If it’s in really bad condition, it might need to be replaced. That’s a big, expensive job.
Let’s say your foundation is made of stone rubble (we see these in older parts of Toronto and other cities across the country). These are loose and crumbly, and when you mess with them, you get all kinds of sand coming out of the joints. The foundations look heavy and solid, but they are very porous, which means water passes right through them, and you’re going to need to waterproof before you do any finishing of the space. Even if your house has a block or concrete foundation, you should have it inspected before you start any basement renovations.
If you want to read more advice from Bryan's book, you can buy it here. Happy reading!