Despite our recent record-breaking deluges, I'm not as concerned about the Gatineau River flooding as I am about flooding from other sources. I'm way more pumped about heavy rains, streams and overland flooding.
In my previous life as a contractor I worked on a house that was actually a converted cottage that had been built on blocks. The hill directed spring rains into the house some years so I built a catch basin and installed a 24-inch culvert under the middle of the house. Presto! Water problem solved. You might think in that case a full basement would be less susceptible but a basement may not have parted the waters. It's hard to make a basement waterproof, and water is sneaky. That wasn’t so bad when I was a kid: the basement was for damp, hockey and millipedes (which give me the willies to this day). Now people finish, furnish, flood, flush and repeat.
Floods are consistently the costliest disasters in Canada. The Insurance Bureau of Canada (IBC) claims the average cost to repair a flooded basement is over $40k. That's because we finish our basements and use them as living space more and more. It's also because we’re getting more rain events here, like the biblical, record-breading deluges in the summer of 2024. And we are still building in risky places.
We generally don't build our homes to manage that much water. Since 2015, some (not all) insurers have offered "overland flood insurance" as an extra rider on your property insurance policy. If you didn't specifically ask for that rider, you likely are not covered, and might want to ask your insurance broker about a flooding rider. And if your basement flooded in the past, that overland flood rider might get really expensive, or even denied. In the past governments paid for recovery from big storms. Currently the feds and insurers are changing the rules around who pays for the recovery of flooded homes and neighborhoods. This is how insurers and governments are trying to transfer flood risk from all insured homes and all taxpayers to higher risk home owners only. Keep your eyes out for new flood maps from the feds and the Province of Quebec coming soon that tell home owners and insurers who is at most risk. Could be that nobody bails you out next time if you have flooded repeatedly.
In the Hills we build on steep slopes, by lakes, and near placid creeks that become torrents in the spring and during storms. We seem oblivious to increasing risk. I’ve heard people say “Yah we get water in the basement. It’s not a big deal”. Many homes here have sump pumps and I’ve seen gutters built into basement floors. This might seem logical except repeated water infiltration can create rot and mold, ruin your stuff and make your house unsafe. Get it out pronto with a pump, wet vacuum, fans and dehumidifiers. Incidentally, those floor-model air conditioners with the duct you put out through a window are excellent dehumidifiers.
But it’s best to stop water from entering in the first place. Infiltration is often hard to diagnose. If water’s coming in from under your basement floor, or the water table is really high at your home, you might be stuck with it because the solutions can be really expensive. That's when you deal with infiltration inside the house with raised flooring and sump pits. However, in my experience most water in basements comes from above ground. Think of it this way: if your basement gets wet only when it rains and/or during the early spring melt, that water's likely coming from the surface, yes? There are expensive solutions like excavating and waterproofing the whole foundation, but sometimes the solutions are really simple. Here are a few.
First, especially during hard rains or when it rains on frozen ground, ensure that water goes away from your house rather than towards it. This often means evaluating your grading - preferably before a downpour! - and simply adding wheelbarrows of soil and some grass seed at the foundation. Backfill settles over time, changing the grade at the house and directing water to the foundation. There are a bunch of other simple things you can do. Here are some:
remove barriers like garden borders that prevent water from escaping;
keep trees away from the house because they can cause problems with foundation footing drains (and septic pipes, incidentally);
install gutters where you can't manage water on the ground;
install window wells with plastic covers on windows close to grade;
On a slope, build berms or shallow trenches uphill to direct water around the house;
avoid plantings close to the house because they may hold moisture and interfere with your drainage
Here's another easy but non-obvious solution: during the spring melt, If we have lots of snow, and especially if you shoveled your roof, dig channels so melt water and rain water can get away from the house. Note that foundation walls can transfer heat outside, melting frozen earth against the wall, and allowing water to get to the footing and into the basement. That’s one reason why footing drains are building code mandatory for foundations.
If you’re planning a new house, first check if the lot has flooded in the past. Insurers gasp like fish out of water when it comes to a home in a marsh. Some other tips:
Design roof slopes to shed water downhill, and build large roof overhangs to keep water away from your house (and protect windows and doors and keep summer sun out too);
Raise your foundation, door sills and windows well above the finished grade;
Make sure that your lot grading is designed from the start to direct water away from your house;
Have your builder compact the material as they backfill your foundation (S/he will know what I mean);
Use backfill like sand or "pit run" (sand/stone mix) that drains water rather than clay soil which holds water;
Ensure footing drains are properly installed around your foundation;
Install a water barrier under the concrete floor slab, and insulation while you’re at it.
These are basic best practices, and any good builder worth his or her salt water will use them - if s/he is building a basement. But basements are sort of old school now. If your builder wants you to have a full basement, make some waves, tell him his argument doesn’t hold water like basements do, and test the waters for slab on grade construction, which makes way more sense in many cases. During an interview for some research I was conducting a chief building official for a large Ontario city recently said to me "if you dig a 6-foot hole, sooner or later it will fill with water". And every day a little rain must fall, especially here in the hills in the summer of 2024!
Contact Plan4 for a site-specific evaluation and strategy to prevent water infiltration in an existing or planned home.
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