Damp Proof Course (DPC) — What Every South African Homeowner Needs to Know

What a damp proof course is, why so many SA homes don't have one that works, how to test yours, and the modern chemical DPC that stops rising damp without breaking out brickwork.

Ask any builder on the Reef what the single biggest cause of rising damp is and the answer is always the same: a failed or missing damp proof course. The DPC is a physical or chemical barrier built into the wall about 150mm above ground level, and its only job is to stop moisture in the soil from wicking up into your plaster and paint. When it's working, you don't even know it's there. When it fails, you get tide-marks, salt blooms, and that musty smell that no amount of painting can hide.

What is a damp proof course?

A DPC is a horizontal barrier inside the wall that breaks the capillary path between the ground and the brickwork above. In South African homes it's traditionally a strip of polythene, bituminous felt, or slate laid into the mortar bed during construction. Modern homes also use plastic membranes built into the wall plate.

Why so many South African homes have a failed DPC

Pre-2000 brick homes were often built with no DPC at all — it wasn't enforced.
Bituminous felt DPCs become brittle and crack after 25–30 years of seasonal expansion.
Garden beds, paving and driveways were added later, raising ground level above the original DPC line and bypassing it completely.
Renovations punched through the DPC for plumbing, extensions or new doorways without re-sealing it.

How to test whether your DPC is working

You don't need a moisture meter to spot a failed DPC. Walk slowly along the inside and outside of every external wall and look for:

A horizontal tide-mark anywhere from 100mm to about 1 metre off the floor.
White, fluffy salt deposits (efflorescence) along the skirting.
Paint that's blistered, flaking, or won't take a fresh coat for more than a season.
Skirtings or floorboards that have rotted, warped or cupped.
A musty smell in the room even after airing it out.

If you see two or more of these, your DPC is either missing or has been bridged — and no amount of waterproof paint will fix it.

Chemical DPC — the modern fix

Breaking out a brick course to install a physical DPC strip is expensive, disruptive, and rarely necessary anymore. The modern fix is a chemical DPC injection: a silane/siloxane micro water-repellent that's injected (or in our case, applied via a saturating coat) into the bottom course of brickwork. Once it cures it forms a permanent hydrophobic barrier inside the brick itself. That's exactly how our Damp Gone Xtreme DIY kit works, and it's the same active chemistry our crews use on every professional damp proofing job.

DIY chemical DPC vs professional injection

DIY: ideal for single rooms or up to 30m² of wall. Apply with a roller along the bottom 1m of the wall, inside and out. Cures in 24 hours, dry walls within 4–6 weeks.
Professional: required for double-storey, very thick or rendered walls where injection pressure and replastering matter. Backed by a 10-year written guarantee.

How much does a chemical DPC cost in South Africa?

DIY kits start at R300 for a small repair area, R1,500 for a 5L kit (roughly 25m² of wall) and R5,500 for the 25L bulk kit. Professional injection runs R150/m² for Xtreme and R120/m² for Organic, including labour, materials and the guarantee. Either way you're paying for the same chemistry — the difference is who holds the roller and who carries the warranty.

Not sure which route to take? Send us a photo on WhatsApp 064 508 6253 or read our DIY vs professional damp proofing guide.