Nova Scotia’s worst basement flooding is not caused by a rainy month. It is caused by a single afternoon.
A post-tropical system tracks up the coast and drops 80 to 150 mm of rain in a matter of hours, more than the ground can absorb in two days. The soil saturates, the water table jumps, and hydrostatic pressure against your foundation goes from negligible to substantial in an afternoon.
And at the same time, wind takes down limbs and the power goes out.
That combination is the whole problem
Your basement is taking on the most water it will see all year, and your sump pump has no electricity. Sometimes for a day or more.
This is why we are so insistent about battery backup. It is not an accessory. A grid-powered pump is offline for precisely the hours it is most needed, and every storm season we get calls from people who discover that in the worst possible way.
A backup system is a second pump on its own float switch, wired to a deep-cycle battery on a maintainer. When the primary loses power or fails, it starts automatically and will typically run through a multi-hour outage. An alarm tells you it has engaged.
If you live along the exposed coast, the St. Margarets Bay corridor, the Eastern Shore, the South Shore, treat it as required equipment. See sump pump installation.
The pre-season checklist
Clear the gutters. A blocked gutter overflows at the wall, which concentrates roof water exactly where you least want it. Do this before the season, not during it.
Extend the downspouts. An average roof sheds several thousand litres in a single significant rainfall. A downspout ending 30 cm from the foundation delivers all of it into the backfill against your wall. Getting it a few metres out onto falling grade is the highest-value hour you will spend.
Test the pump with real water. Pour a bucket in until the float rises. It should start promptly, empty the basin and stop. Then walk to the discharge point and confirm water actually comes out, well away from the house.
Test the backup. Unplug the primary and repeat. Check the battery date, most need replacing every three to five years.
Check the grade. Ground should fall away from the wall, roughly 15 cm over the first 2 m. Settled backfill very often reverses this.
Clear window wells. A well full of leaves is a well that will fill with water, and a basement window is a weather barrier, not a below-grade waterproofing product. See window wells.
Look at low spots. Anywhere water pools near the house is somewhere it will soak in for hours. A French drain intercepts it before it arrives.
Coastal properties have two extra concerns
Salt. Steel corrodes far faster within sight of the water. Window wells, exterior fasteners and discharge hardware all have shorter lives here, and we specify galvanized or composite components as a default rather than an upgrade.
Tidal influence on the water table. In low-lying coastal areas (Eastern Passage, parts of Cole Harbour, the Eastern Shore), groundwater responds to conditions in the harbour, not just to rainfall. Basements there can take water on a clear day, which is genuinely confusing until you know why.
Converted seasonal properties
A large share of the South Shore and Eastern Shore housing stock is cottages converted to year-round use. They were built on crawl spaces and shallow foundations for summer occupancy, and they are now being asked to hold back an Atlantic winter with a heated floor above.
Crawl space encapsulation is very often the single highest-value project on these homes. It addresses moisture, air quality, comfort, and the long-term survival of the floor structure at once.
Before the season, not during it
Every year we get the same call in early September from people who meant to sort it out in July. The work is the same either way; the difference is whether the basement is dry when you book it.
Written by the crew at Maritime Basement Waterproofing.
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