HOW-TO · WATERPROOFING

How to stop dampness and rising damp in walls

Damp patches, peeling paint and musty smells all trace back to water getting in. Here is how to find the source and stop wall dampness with SUMO Sealcrete and Dampguard.

LEVEL

Intermediate

TIME

Varies by cause

STEPS

WHO THIS IS FOR

Homeowners and applicators tackling damp patches, rising damp and seepage in walls.

Wall dampness has three common causes: rising damp (moisture wicking up from the ground), penetrating damp (rain or a leak coming through), and condensation. The fix depends on the cause — treating the wrong one wastes effort — so this guide starts with diagnosis, then treatment with SUMO Dampguard and Sealcrete.

BEFORE YOU START

What you’ll need

DAMPGUARDdamp-proof treatmentDamp & Seepage Wall Coating10 kg→SEALCRETEwaterproof coat / repairAcrylic Waterproofing Liquid1 kg→

Wire brush, brush/roller, mixing gear

THE METHOD

Step by step

Find the source first

Rising damp shows as a tide-mark low on the wall; penetrating damp appears as patches linked to rain or a leak; condensation forms on cold surfaces. Identify which before treating.

WATCH OUTCoating over damp without fixing the source just traps it and pushes it elsewhere. Diagnose first.

Fix the water source

Stop the water getting in — repair leaking pipes, gutters, flashings or external cracks, and improve ventilation for condensation. Let the wall dry out.

Prepare the affected surface

Remove blown plaster, salts and flaking paint back to a sound surface, and brush it clean.

Treat with Dampguard / Sealcrete

Apply SUMO Dampguard to check the damp, and/or a Sealcrete waterproof coat where water is penetrating, following the product method and coats.

PRO TIPMatch the product to the cause — a surface treatment stops penetrating/seepage damp; rising damp needs the source and DPC addressed.

DAMPGUARDPRODUCT USED IN THIS STEPDamp & Seepage Wall Coating10 kg→

Re-plaster and finish

Once treated and dry, re-plaster with SUMO Ready-Mix Plaster, apply putty and repaint.

PLASTERPRODUCT USED IN THIS STEPReady Mix Plaster40 kg→

AVOID THESE

What to avoid

!Painting/coating over active damp

It traps moisture and blisters. Fix the source and let the wall dry first.

!Treating the wrong cause

Rising, penetrating and condensation damp need different fixes. Diagnose before treating.

!Not removing salts/blown plaster

Treat a sound surface — strip damaged plaster and salts back first.

QUESTIONS

FAQ

How do I stop damp in a wall?+

Find the cause (rising, penetrating or condensation), fix the water source, prepare the surface, then treat with SUMO Dampguard/Sealcrete and re-finish once dry.

Why does my paint keep peeling on a damp wall?+

Water behind the paint pushes it off. Stop the water, let the wall dry, treat the damp, then repaint.

Can I just paint over a damp patch?+

No — that traps the moisture. You must address the source and treat the wall first.

THE KIT

Products used in this guide

DAMPGUARDSUMO PRODUCTDamp & Seepage Wall Coating10 kg→SEALCRETESUMO PRODUCTAcrylic Waterproofing Liquid1 kg→PLASTERSUMO PRODUCTReady Mix Plaster40 kg→SBR LATEXSUMO PRODUCTPolymer Waterproofing Latex1 kg→

NOT SURE ON YOUR JOB?

Send us your substrate and tile size — our technical team will confirm the exact method.

Read the datasheet →