Part of Ward Property Services UK LtdPlaster damaged by damp cannot simply be skimmed over. Where moisture has evaporated through a wall for years, hygroscopic nitrate and chloride salts accumulate in the plaster and continue to draw moisture from the air even after the wall itself is dry. Ordinary gypsum plaster applied over contaminated masonry will stain and blow within months.
We use the right system for the wall. Renovating plaster with a salt-inhibiting additive for treated walls following DPC installation; breathable lime plasters for solid-wall period properties where vapour needs to pass through; and standard finishes where the substrate is genuinely sound. Finish quality matters too — repairs are feathered and floated so the wall reads as one surface once painted.
Common signs
- ✓ Bubbling, hollow-sounding plaster that crumbles at a touch
- ✓ Salt crystals reappearing through fresh paint
- ✓ Patchy staining that returns weeks after redecorating
- ✓ Cracked and detached plaster around a repaired leak
- ✓ Skirtings removed for damp works leaving open wall sections
Likely causes
- • Long-term rising or penetrating damp depositing salts
- • Escape of water saturating plasterboard and gypsum
- • Incompatible modern cement renders on solid walls
- • Poor preparation during previous repairs
- • Movement and settlement cracking exacerbated by moisture