Raised Beds Near House Foundations: Drainage & Waterproofing Essentials

Building a raised flower bed against a brick house wall risks water infiltration if soil contacts the veneer above the waterproofing line. Never raise soil higher than the finished floor elevation unless the foundation was specifically designed for it. Water trapped against brick can seep into framing, causing rot and mold.

If you must raise the bed, install a fluid-applied waterproof membrane against the foundation, protected by drainage board and filter fabric, with a French drain at the base to divert water away. Alternatively, keep soil 6–12 inches below the waterproofing line, slope a berm away from the house with drainage breaks, or excavate the clay soil entirely and replace it with well-draining loam at the original grade—achieving better soil without raising the bed.

French drains in raised beds require a perforated pipe wrapped in filter fabric, bedded in gravel, sloped to daylight or a sump. Position it at the bed's low point, behind the retaining wall. Always verify local building codes and consult a landscape architect for site-specific design.