Landscaping a Re-Graded Foundation Slope: Impermeable Aprons vs. Plantings

What to Put on a New Foundation Backfill Slope

After raising grade 12" over 10 ft run against basement wall, surface treatment affects long-term dryness.

Best: Impermeable Apron

• Concrete, mortared pavers, or mortared stone extending 3 ft out.
• Sheds water completely; eliminates seepage through backfill.
• Clay cap (compacted clay) is semi-permeable alternative.

Acceptable: Plantings with Caveats

• Shrubs/groundcover 5 ft from wall (root/water separation).
• No organic mulch against siding (termites, moisture).
• Stone mulch or bare ground near wall.

If Seepage Persists

• Plastic sheeting (pond liner) buried against wall, covered with soil/plants.
• Exterior waterproofing membrane (pro installation).

Soil Considerations

• Clay backfill = less seepage but poor for some plants.
• Amend planting areas only; keep wall zone lean.

A 10-ft run at 12" rise (10% slope) is good. Extending impermeable surface 3 ft maximizes protection.