Damp Under Suspended Timber Floors — Signs, Causes and Fixes

Older East Rand homes — particularly pre-1970s builds in Benoni, Boksburg and Germiston — often have suspended timber floors over a shallow crawl space. When those crawl spaces get damp, the floors above start to cup, creak and smell musty long before you see any visible damage.

The warning signs

• Musty smell strongest at floor level, especially in winter.
• Floorboards cupping, warping or feeling springy underfoot.
• Skirtings lifting away from the wall.
• Visible mould on the underside of the boards (check via air brick or hatch).

The three common causes

• Blocked or built-over air bricks — the crawl space can no longer breathe.
• Ground levels raised outside the house, bridging the DPC and flooding the void.
• A slow plumbing leak (bathroom, kitchen) draining into the crawl space for years.

The fix

Clear or reinstate air bricks, fix any raised ground bridging the DPC, and treat the base of the walls (inside and outside) with Damp Gone Xtreme. In severe cases we lift a few boards and treat the sub-floor brickwork directly. Book a professional inspection before floorboards need replacing — it's a lot cheaper to fix damp than to relay a floor.