· Michael Blair
Grade around a house settles over decades, and beds get built up with mulch year after year. The result is ground sloping toward the foundation, which is exactly the wrong direction on Middle Tennessee clay.
Recognising it
Stand at the wall and look outward. Water should visibly run away. Mulch or soil piled above the brick ledge or against siding is a clear sign, and so is a bed that ponds after rain.
A string line and a level answers it definitively over ten feet.
How it is corrected
Adding soil to build fall away from the house, keeping the finished grade below the siding line and below any weep screed or brick weep holes.
Clay-rich soil is appropriate here rather than free-draining topsoil, because you want water to run off the surface rather than soak in beside the footing.
- Six inches of fall over the first ten feet
- Keep grade below siding, weep screed and brick weeps
- Use clay-rich fill, not free-draining topsoil
- Do not bury the brick ledge or cover weep holes
- Combine with downspout extensions
Do not bury the wall
Raising grade above the brick weep holes or a weep screed blocks the drainage path out of the wall assembly, which causes rot behind siding and moisture in brick.
It is a common mistake made while solving a drainage problem, and it creates a worse one.
With downspouts
Regrading and downspout extension work together — good grade with water dumped onto it beside the wall achieves little.
Doing both is usually the whole solution on a house whose problem is surface water rather than groundwater.