Raised Garden Bed Against a Brick House Wall: Preventing Water Damage

A homeowner plans a 24-inch-high raised bed with its back against the home's brick exterior. The soil level will sit above the interior floor level, raising concerns about moisture seeping through the brick and causing water damage or mold.

Expert Recommendation: Don't Do It

The safest, most reliable approach is to not place soil directly against the house. Neither the homeowner nor a typical contractor is equipped to properly waterproof this detail. The risk of long-term structural damage, mold, and costly repairs far outweighs the aesthetic benefit.

Better Alternative

Build the raised bed with a solid back board (e.g., pressure-treated lumber, composite, or metal) and leave a 2–3 inch air gap between the board and the brick wall. This simple detail:

• Allows airflow to keep the brick dry.
• Prevents hydrostatic pressure against the foundation.
• Provides access for inspection and maintenance.
• Eliminates the need for complex waterproofing.

If the bed must abut the wall, consult a structural engineer or waterproofing specialist for a designed system (drainage mat, waterproof membrane, protection board, and weep holes)—but expect significant cost and complexity.

Expert: Sean J. Murphy, LA, ISA, LEED AP | www.seanjmurphy.com