Waterproofing a Below-Grade Garage: Interior Sealants vs. Exterior Barriers

A buyer looking at an 80-year-old brick garage set a foot below grade reports damp interior walls and musty smell. Roof leak fixed, shingles replaced. Asks if it's a DIY project.

Two Scenarios

• Exposed brick/block walls: Clean, caulk, and apply masonry sealant inside—like basement waterproofing.
• Brick veneer over stud walls: Excavate to the footing, glue a rubber membrane from above grade down to the footing, then backfill.

Additional Steps

If interior drywall is damp, remove and inspect for mold. Not easy work, but a good independent hardware store can guide product selection—worth the extra cost over chain stores.