Basements are for Potatoes – not Couch Potatoes

Basements are for Potatoes; no, not couch potatoes.

If that’s what you were thinking, then you’re not alone. Millions of Canadians use their basements as living space, thinking it’s the ideal space to set up a family room, games room, or even kids’ bedrooms.

But in truth, it takes a great deal of careful design and maintenance to avoid water and moisture infiltration in even the best cases. And oftentimes, moisture accumulation results in a nasty – and costly – surprise to the hapless homeowner.

Recently I heard a news report about a woman living in Laval whose basement was flooded when the sewers backed up. The insurance company covered the losses of about $50,000 and the basement was repaired. Not long after, it happened again even though she had installed a backwater valve meant to prevent the sewage from entering the house. This time the insurance company refused to pay.

A little history about basements
Up until about the 1950s, residential basements were rarely “finished” for use as living space as they often are today, and with good reason.

Before about 1900 basements were mostly used as cellars; storage for items such as preserves, wine, and yes, potatoes. Then as we started to install furnaces, electrical and plumbing systems, the basement was naturally a good place for them. Expensive houses were built with full height basements, while more modest housing only had a crawlspace with a dirt floor.

Nowadays, the use of sump pumps and proper drainage and construction materials has gone a long way towards making basements comfortable living spaces. But in the end, there is only so much one can do to keep groundwater from seeping in at some point. Some factors are simply outside the homeowner’s control (such as the surrounding geography and adequacy of the local municipal sewer and drainage network).

Steps to Take to Reduce the Risks
With the increasing frequency of severe weather we have to be more and more careful with how we handle the surface water around our houses. Here is a short list of things to do:

  • Check the grading around the house. It should slope away at least 1 metre within 12 metres of the building.
  • Ensure gutters and downspouts are installed, and discharging 2 metres away from the house.
  • Install a backwater valve and test its operation every six months.
  • Have a plumber check the sump pump installation. It must discharge outside.
  • Inspect the garage floor drain and clean it every six months.

Meanwhile, if you haven’t already got a finished basement, but are planning to do so, there are a few things you should take into consideration before embarking on the enterprise.

Is your house well situated? Ideally it should be a little higher than the surrounding properties and well away from any river or lake. Any history of flooding in the area? Houses in Quebec’s Richelieu valley for example should not even have basements.
Does the city have storm water sewers that are separate from the waste sewers? If not, there is a higher risk of backup in the event of heavy rain.
Does the grading around your house slope away from the house for at least 10 feet? Do all your downspouts discharge at least 6 feet from the house? 90% of water flows away and only 10% soaks in. It is not a good idea to allow the french drain to take care of everything (because it won’t).
Does the sump pump discharge directly outside to the ditch or the storm drain? If it discharges directly into the sewer line inside the house, as it does in many houses, then there could be a problem. During a major rainstorm the sewers may become overloaded and start to backup. At that point, the backwater valve should close automatically to protect the house. The sump pump then turns on to remove the accumulating water, but that water has nowhere to go because the sewer pipe is full, so the basement floods anyway.
Think twice before finishing your basement. If in doubt, call a house inspector to look at your situation and advise you on what you have to do.