Clay, grade and the water sitting in your yard

Most GTA subdivisions sit on heavy clay that was driven over by machinery for months during construction, then covered with a thin skin of topsoil. Almost every drainage complaint we get traces back to that one fact.

What compacted clay does

Water cannot move down through it at any useful rate. So it does one of two things: sits on the surface until it evaporates, or runs across the surface to the lowest point — which, on a lot graded by a builder in a hurry, is sometimes the corner of your foundation.

Roots cannot get down either. Which is why a five-year-old lawn in a new subdivision often looks worse than a forty-year-old lawn on an established street.

The symptoms, and what each one means

Puddles that last a day after rain — surface grade is flat or reversed there.
A permanently soft corner — water is arriving faster than it can leave; usually a downspout or a neighbouring grade.
Moss in the lawn — shade plus constant moisture plus compaction.
Efflorescence or damp on a basement wall — water sitting against the foundation.
Interlock that heaves in one area only — water collecting under that part of the base.

What actually fixes it

Grade first. Moving water with slope is free forever and needs no maintenance. Most yards can be substantially improved by re-grading alone.

Then drainage. Where grade cannot do it — a low corner, a side yard between two houses, a patio that has to be level — you install drainage: catch basins, perforated pipe in clear stone, and a discharge point that is lower than the problem. A pipe that ends nowhere achieves nothing.

Downspouts and sump. Extend them away from the foundation and away from where people walk. An astonishing number of wet yards are one downspout emptying beside the house.

Soil, last. Amending and aerating helps the top 100 mm, which matters for turf, but it is not a substitute for the first three.

Never build a patio over a drainage problem. Fix the water, then lay the stone.