Interior Perimeter Drainage, Dartmouth

The problem

The homeowners had spent two seasons trying to solve this from the wall. Sealant, waterproof paint, and a crack injection on the one visible crack: none of it changed anything, because none of it addressed where the water was actually coming from.

The pattern told the story immediately. Water appeared as a line around the perimeter of the floor, not running down any wall. The walls above it were dry. It showed up hours after the rain rather than during it, and it was worst during spring melt.

That is water coming up through the cold joint where the slab meets the footing, driven by a water table sitting above the underside of the floor. Nothing applied to a wall can affect it.

What was done

A channel was cut around the interior perimeter and excavated beside the footing, never beneath it. Perforated pipe was bedded in clean washed stone and the whole envelope wrapped in filter fabric, so the void space that actually carries the water cannot silt closed.

Dimple board was run up the wall and lapped down into the stone bed, so any seepage through the concrete above is channelled into the drain rather than onto the floor.

The system was sloped to a sealed sump basin at the low corner. A cast-iron primary pump handles normal flow, and a battery backup on its own float takes over automatically if the power drops.

New concrete was placed and finished flush, and the system was flood-tested before handover.

Why the backup mattered here

This basement floods during the same storms that take out the power in this part of Dartmouth. A grid-powered pump is offline for precisely the hours it is most needed. The backup runs for several hours of intermittent cycling on its own battery. It is the component that makes the rest of the system dependable.

Result

Dry through the following spring melt, including a week of sustained rain that put the water table at its seasonal peak.