How to Treat Rising Damp on Internal Walls — A South African Step-by-Step Guide

A practical, weekend-friendly guide to permanently treating rising damp on internal walls in South African homes — what to strip, how to apply Damp Gone Xtreme, and how long until you can repaint.

Internal walls are where rising damp shows up first and worst. Bedroom skirtings start lifting, plaster crumbles behind the bed, and the wall behind your TV unit grows a halo of dark patches. The good news: treating rising damp on an internal wall is one of the most DIY-friendly jobs in home maintenance — if you follow the right sequence and don't skip the prep.

How do you know it's rising damp and not something else?

Rising damp has three tell-tale signs that almost never lie:

A horizontal tide-mark between 200mm and 1m off the floor — never higher.
Salt deposits (white powdery efflorescence) along the skirting that come back even after you wipe them off.
Damage worse in winter and spring, when the soil is still wet from summer rain.

If your damp patch is up near the ceiling, around a window, or only behind a shower, it's probably penetrating damp or condensation — not rising. Read our mould and condensation guide for that scenario.

What you'll need (R1,500 budget, 1 weekend)

Damp Gone Xtreme 5L kit (covers ~25m² of wall, inside + outside if you can access it).
Wide paint scraper and 80-grit sandpaper.
Dust sheet and masking tape.
Cheap 100mm paint roller and a 50mm cutting-in brush.
P2 dust mask and nitrile gloves.
Bucket of clean water and a sponge.

Step 1 — Strip back to a sound surface

Move the furniture away from the wall and lay down dust sheets. Scrape off all flaking paint, blown plaster and loose render up to at least 300mm above the visible tide-mark. If the plaster sounds hollow when you tap it, it has to come off — Xtreme treats the brickwork behind the plaster, not the failed plaster itself. Vacuum the debris and wipe the wall with a damp sponge to lift loose salts.

Step 2 — Treat the bottom 1m of wall, inside and out

Stir the Xtreme thoroughly. Pour a small amount into a roller tray and apply two saturating coats to the bottom 1m of the wall, allowing 4 hours between coats. The liquid should soak into the brick — if it beads off immediately you've got paint or sealant in the way and need to strip more. Don't dilute it. Don't skimp at the corners.

For best results, treat the outside face of the same wall as well. Rising damp comes through from both sides of a single-brick wall, and treating only one face leaves a moisture path. If the outside is rendered, our crews handle this on every professional damp proofing job.

Step 3 — Wait. This is the step everyone skips.

Brickwork that's been wicking moisture for 20 years has a lot of trapped water and salts to release. After treatment, leave the wall bare for 4–6 weeks (longer in winter) before replastering or painting. Open windows daily. If you replaster too soon, the salts come straight through your new finish and you'll think the treatment failed — it didn't, you just sealed wet brick.

Step 4 — Replaster with a salt-retardant render

Once the wall reads dry on a moisture meter (below 5%), replaster with a salt-retardant render — your local builder's merchant stocks it as 'waterproof plaster' or 'render additive'. Standard cement plaster will let salts through. Skim, sand and paint with a breathable interior paint.

When to call a professional instead

Double-storey wall or anything above 2.5m on the inside.
Wall shared with a bathroom or kitchen with active leaks.
Heritage home with hand-pressed bricks or lime mortar.
Damp that's already caused floor or skirting rot.

In any of those cases, book a Professional Inspection — via our professional damp proofing service or WhatsApp 064 508 6253. Otherwise grab a Damp Gone Xtreme DIY kit and knock it out this weekend.