Basement Wall Construction

Basement walls must resist lateral soil pressure. Poured concrete or properly grouted CMU block required. Reinforcement per structural plans.

1. Verify wall type matches plans (poured concrete or CMU block)

2. For concrete walls: check for honeycombing, voids, or cold joints

3. For CMU walls: check that all cores are grouted solid (required for structural walls)

4. Verify horizontal and vertical reinforcement per plans

5. Check wall thickness — minimum 8" for most residential basements

6. Verify wall is plumb and straight

7. Check for cracks — hairline is normal, anything wider than 1/8" needs evaluation

8. Verify anchor bolts for sill plate are in place

- Honeycombing or voids in concrete (weak spots)

- CMU cores not grouted (wall has no strength)

- Missing reinforcement

- Wall too thin

- Wall not plumb or bowing

- Large cracks indicating structural issues

- Missing anchor bolts

Exterior of basement walls must be waterproofed before backfill. Foundation drain (perimeter drain) required at footing level.

1. Verify waterproofing membrane applied to exterior (should be visible before backfill)

2. Check membrane type — liquid-applied, sheet, or spray — must cover entire wall area

3. Verify protection board or drainage mat over membrane (prevents damage during backfill)

4. Check perimeter drain pipe at footing level — 4" perforated pipe in gravel

5. Verify drain connects to sump pit, daylight, or storm system

6. Check that backfill material is free-draining (gravel or sand, not clay)

7. Verify damproofing vs waterproofing — for habitable basements, full waterproofing required

- No waterproofing on exterior walls (most common cause of wet basements)

- Membrane not extended to footing level

- No protection board (membrane punctured during backfill)

- Missing perimeter drain (water has nowhere to go)

- Perimeter drain clogged or with no outlet

- Clay backfill holding water against wall

- Damproofing used instead of waterproofing (damproofing only resists moisture, not water pressure)