Damp-proofing resists moisture and water vapour moving through a surface, while waterproofing holds back liquid water under pressure — waterproofing is the stronger, more complete barrier. Damp-proofing suits walls managing rising or penetrating damp, such as an interior face treated with Damp Proof; waterproofing suits roofs, wet areas and below-ground walls that take direct or standing water, such as Shield or Megaflex.
The difference between damp-proofing and waterproofing paint
A damp-proofing paint slows moisture and vapour; a waterproofing paint blocks liquid water entirely. A waterproofing membrane carries more binder and flexible polymers to form a continuous water barrier, while a damp-proof coating manages moisture and salts on a wall face. Use damp-proofing where the problem is damp; use waterproofing where the problem is water.
What is the purpose of damp-proofing?
The purpose of damp-proofing is to stop rising and penetrating damp from reaching the internal wall face and finish. It keeps moisture and the salts it carries from blistering paint and feeding mould, so the wall stays dry and paintable. It is a moisture-management step, not a defence against standing water.
How many years does damp-proofing last?
A quality damp-proof coating lasts around 5 to 10 years, and a chemical damp-proof course can last far longer. Lifespan depends on the severity of the damp and whether the source was fixed. A waterproofing membrane like Shield carries a 10-year warranty on walls.
Damp-proofing vs waterproofing cost
Damp-proofing a wall face with a coating is the cheaper job; full waterproofing with a membrane or a new damp-proof course costs more but solves a bigger problem. A litre of waterproofing coating costs more than ordinary paint because of the higher binder load, but on a roof or wet area it is the only option that lasts. Match the spend to the problem — a coating for damp management, a membrane where water must be held back.
Coatings, membranes and a damp-proof course
- Damp-proof coating — a surface treatment like Damp Proof that manages moisture on a wall face.
- Waterproofing membrane — a continuous barrier like Shield on walls, Fiber Coat on roofs, or Megaflex below ground.
- Damp-proof course (DPC) — a physical or chemical barrier in the wall that stops rising damp at its source.
When you need both
A wall with rising damp often needs both: a damp-proof course to stop the source, then a damp-proof coating on the repaired face. Sealing the outside with waterproofing and managing the inside with damp-proofing is the two-sided approach used on coastal and older homes.
Which to use on walls, roofs and bathrooms
- Interior damp walls: damp-proofing with Damp Proof.
- Exterior walls and roofs: waterproofing with Shield or Fiber Coat.
- Bathrooms and below ground: cementitious waterproofing — Megaflex under tiles, in showers and below ground.
Frequently asked questions
What is the difference between damp-proofing and waterproofing paint? Damp-proofing slows moisture and vapour; waterproofing blocks liquid water. Waterproofing is the more complete barrier for roofs, wet areas and below ground.
How long does damp-proofing last? Around 5 to 10 years for a coating; a chemical damp-proof course lasts longer. Fixing the moisture source is what protects that life.
Do I need both damp-proofing and waterproofing? On a wall with rising damp, yes — a damp-proof course to stop the source and a damp-proof coating on the face, with exterior waterproofing to keep rain out.
Where to buy
Shop Damp Proof and the Waterproofing range, or read the complete waterproofing guide. Trade pricing: +27 84 985 6141.
