When the garage was built, the concrete below the soil line should have been waterproofed. A perforated drain pipe should have been placed alongside or on top of the footing that supports your ...

To install a french drain, you'll need a perforated drain pipe such as this one, which is available in a range of sized (including 25m x 69mm, 25m x 100mm, 50m x 60mm, and 50m x 100mm).

Laying the Pipe: Place a perforated drain pipe on top of the gravel, with the perforations facing downward. This allows water to enter the pipe while keeping sediment out.

Install the filter sleeve on the perforated pipe, if it didn’t come pre-installed. Then lay the drain pipe in the bottom of the lined trench. Backfill the remainder with clean drainage gravel.