Before recommending anything expensive, we look at where the water is coming from. On a meaningful share of the wet basements we assess in Halifax, the water never came from the water table at all. It fell on the roof or the yard, and grade delivered it to the foundation.
That is genuinely good news, because surface water is the cheapest category of problem to fix.
Read your own property first
Three things to check, free, this week.
Downspouts. Where does each one actually end? An average Halifax roof sheds several thousand litres in one heavy rainfall. A downspout discharging 30 cm from the wall puts all of it into the soil directly against your foundation, where it saturates the backfill and pushes against the concrete. Extensions cost very little and resolve a surprising number of problems outright.
Grade at the wall. The ground should fall away from the foundation: roughly 15 cm of drop over the first 2 m. Over decades, backfill settles and landscaping gets added, and grade very commonly ends up flat or tilted back toward the house.
Flow paths. After the next heavy rain, go outside while it is still running. Where does water pool? Which way does it move? Does the neighbouring property drain toward yours? Water standing anywhere near the foundation is water being given time to soak in.
What a French drain does
A French drain is a trench filled with clean washed stone containing a perforated pipe, positioned to intercept water upslope of whatever it protects. Water in the soil finds the stone, which offers far less resistance than the surrounding ground, enters the pipe, and gravity carries it away.
The system works because of the stone as much as the pipe. Roughly a third of a washed stone bed’s volume is air, which is why it accepts water so much faster than soil does. The pipe is simply the fastest route through the stone once the stone has collected it.
Filter fabric is not optional. It lines the trench and folds over the top of the stone before backfill, letting water through while keeping soil fines out of the void space. French drains that quietly stop working after four or five years are almost always drains built without it.
The outlet decides everything
The most common French drain failure is not construction. It is that nobody established where the water was going before the digging started.
A gravity drain needs an outlet at a genuinely lower elevation. On a sloped lot (much of Bedford, much of the peninsula’s edges), that is straightforward: the line runs to daylight somewhere downhill. On a flat lot, such as parts of Cole Harbour or Eastern Passage, it can be the hardest part of the job, and the honest options narrow to a properly sized drywell, a permitted storm connection, or a pumped basin.
Two rules that are not negotiable in HRM:
- You cannot discharge onto a neighbouring property. That is a liability problem, and a neighbour problem.
- You cannot connect storm water to the sanitary sewer. It is prohibited, it overloads treatment plants, and it backs sewage into other people’s basements.
We confirm the outlet before we quote the trench. If there is no viable outlet, the trench is a hole that fills with water.
French drain, trench drain, or weeping tile?
These get used interchangeably and they are three different things.
Weeping tile is foundation drainage. It sits at the footing, at the bottom of the foundation, and manages groundwater against the house. See exterior weeping tile.
A French drain is landscape drainage. It sits shallower and is placed to intercept surface and near-surface water moving across a yard.
A trench drain, or channel drain, is a surface grate set into hard surfaces: a driveway apron, a garage entry, a walkout landing. It captures water already running across pavement.
Plenty of Halifax properties need more than one. A trench drain at the driveway, a French drain in the soft landscape, and downspout extensions feeding into neither of them.
How deep?
It depends on what is being intercepted. A drain handling surface runoff and shallow saturation typically sits 45 to 60 cm deep. A drain meant to lower the water table around a specific area, or to protect a foundation wall directly, needs to sit deeper, sometimes near footing depth, at which point it is really foundation drainage.
Depth is set by the job, not by a standard number.
Where this fits
Yard drainage is unglamorous, and it is frequently the cheapest permanent solution to a wet basement. If your assessment shows surface water is the driver, that is what we will quote, not an excavation you do not need.
More on the work itself: French drains and yard drainage.
Written by the crew at Maritime Basement Waterproofing.
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