- Lateral damp is moisture moving sideways into a wall from soil or fill on the other side.
- It is common where ground is higher than the inside floor: split-level homes, hillside plots, raised garden beds and paving against walls.
- A DPC injection does not stop it, because the water comes in from the side, not from below.
- Describe the problem once and compare quotes from contractors across Cape Town.
Tell us about the problem and compare quotes from lateral damp treatment specialists in Cape Town.
Compare QuotesSigns of Lateral Damp
- Damp up to the level of the ground or bed on the other side of the wall.
- Damp on walls that are partly below ground.
- Patches behind built-in cupboards against an outside wall.
- Worse after heavy rain or irrigation.
Causes and What the Assessment Should Establish
- The ground level outside compared with the inside floor.
- Whether a membrane or tanking was ever installed.
- Where surface and ground water drain, and whether it collects against the wall.
- Whether the problem is lateral damp, rising damp or both.
Treatment Options and Their Limits
| Option | What it does | Limitations |
|---|---|---|
| Lower the ground or remove beds | Takes soil and paving off the wall | Not possible on split-level or boundary walls |
| External membrane | Waterproofs the soil side of the wall | Needs excavation and access |
| Internal tanking | Waterproof render or slurry on the inside face | Holds water back but does not stop it reaching the wall |
| Drainage | Moves water away from the wall | Works with waterproofing, rarely instead of it |
For walls holding back soil, see retaining wall waterproofing. For rooms below ground, see basement waterproofing.
What the Work May Include
- Removing plaster from the affected wall.
- Excavating and applying an external membrane, where access allows.
- Internal tanking with a waterproof slurry or membrane, then replastering.
- Adjusting ground levels, paving falls or drainage.
Lateral Damp Treatment Prices in Cape Town
| Item | Ballpark price |
|---|---|
| Interior damp proofing coating, per m² | R180 - R350 |
| Internal tanking system, per m² | R800 - R1,500 |
| Soil-side wall waterproofing, per m² | R250 - R550 |
| Exterior French drain, per linear metre | R300 - R600 |
Ballpark figures, not quotations. Indicative 2026 ranges, rounded, from published South African damp-proofing, waterproofing and plastering price guides (Cape Town and Western Cape guides where available, national and Gauteng guides otherwise), checked October 2026. Per-metre prices are per linear metre of wall unless stated. Some include VAT and some do not, so confirm VAT on every quote. A site assessment and a written quote set the actual price.
What changes the price
- Wall area below ground level.
- Whether excavation is possible.
- Tanking system and number of coats.
- Drainage work and reinstating paving or gardens.
Getting Lateral Damp Quotes
Describe what is on the other side of the wall and add photos of both sides. Compare quotes through Damp Proofing Cape Town.
Frequently Asked Questions
Will DPC injection fix lateral damp?
No. Injection stops moisture rising from below. Lateral damp needs a vertical barrier, tanking or ground-level changes.
Can I just move the flower bed?
If the bed is the cause and the DPC is intact, lowering soil below the DPC level can be enough.
Is internal tanking a permanent fix?
It can last well, but it holds water back rather than stopping it. Drainage on the outside helps reduce pressure.
Do split-level homes always get lateral damp?
No, but walls holding back soil need waterproofing. Older split-level homes often lack it.
Related Pages
Damp Proofing Cape Town is a free quote-comparison service. Damp is inspected, quoted and repaired by independent damp proofing contractors, and your agreement is with the contractor you appoint. Ask each one for a written, itemised quote, what is and is not included, guarantee terms and payment terms before paying anything.
Lateral Damp Treatment Cape Town. Describe the damp once and compare lateral damp treatment quotes.
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