Treating Dampness in Walls

Treatment overview — dampness in walls

1. What is dampness?

Dampness is excess moisture within a building fabric. Left untreated it can lead to mould growth, salt contamination, damage to finishes and, in severe cases, structural issues. Common types are condensation, penetrating damp, and the less common rising damp.

2. How damp appears on walls (signs to look for)

• Peeling paint or wallpaper: Finish detaching from the substrate.
• Steamed-up windows and wet surfaces: Typically points to condensation.
• Tide marks (to ~1 m above floor): Often linked with rising damp and salts.
• Discolouration and dark patches: Persistent moisture within the wall.
• Crumbling or blown plaster: Moisture and salts degrading finishes.
• Musty odour: Stagnant moisture and possible microbial growth.
• Mould and mildew: Black spotting or fuzzy growth on cold, damp surfaces.

3. Why it matters (cosmetic, structural, health)

• Cosmetic: Staining, peeling finishes, damaged soft furnishings.
• Structural: Long-term moisture can affect timbers, joists and plaster integrity.
• Health: Damp and mould may aggravate respiratory conditions and allergies.

4. Main causes of damp on internal walls

• Condensation: Warm, humid air meeting cold surfaces (kitchens, bathrooms, bedrooms).
• Rising damp: Moisture travelling up from the ground where a DPC is missing, bridged or failed.
• Penetrating damp: Rainwater entering through defects (leaking gutters, porous masonry, failed pointing/render).

5. External walls & basements — special considerations

• External walls: In wind-driven rain, porous or cracked masonry can absorb water. Faulty gutters/downpipes often exacerbate issues.
• Basements: Groundwater exerts hydrostatic pressure. Solutions are typically tanking (barrier) or Type C cavity drain systems discharging to a sump and pump.

6. First steps — assessment & basic checks

• Visual & smell checks: Look for salts, tide marks, mould, damp patches, musty odours.
• Touch & temperature: Cold, clammy surfaces indicate condensation risk.
• Foil test (indicative only): Tape foil to the wall for 24 hours. Moisture on the room side suggests condensation; moisture on the wall side suggests ingress. Use as a guide only.
• Professional survey: For persistent or complex problems, arrange a competent damp assessment. Avoid relying solely on simple electrical moisture meters for diagnosis.

7. How to fix damp — solutions by type (illustration only)

7.1 Condensation control

• Ventilation: Improve extraction in kitchens/bathrooms; air appropriately.
• Reduce moisture at source: Pan lids, shorter showers, dry clothes outside where possible.
• Balanced heating: Maintain steadier temperatures to limit cold surfaces.
• Finishes that help: Use anti-condensation or thermal liners/paints where appropriate.
• Wykamol options: Anti-mould washes/additives; compatible thermal lining systems; ancillary ventilation solutions specified in the design.

7.2 Penetrating damp

1. Fix defects first: Repair gutters/downpipes, flashings, pointing, cracked render and leaks.
2. Block or control moisture movement: For internal remediation, consider a cavity drain membrane lining (e.g., Wykamol CM3 Mesh or CM8) to isolate finishes from damp substrates.
3. Replastering: After isolation, use breathable or compatible finishes to resist future salt damage.
4. Exterior protection: Where specified, apply a breathable, water-repellent masonry cream to reduce rain penetration while allowing vapour diffusion.

7.3 Rising damp

1. Confirm cause: Check that external ground levels, bridging and splash-zones are addressed. Verify DPC level isn’t bridged by render or internal screeds.
2. Create/restore a DPC: Use a Wykamol Damp-Proofing Injection Cream to form a new chemical DPC in the mortar bed at the correct height (illustrative guidance only—follow product data sheets).
3. De-salt & replaster: After DPC works, contaminated plasters should be removed and replaced with a suitable renovation system or isolate with Wykamol CM3 Mesh before finishing.

8. Internal lining with Wykamol membranes (illustration only)

• Walls: Install Wykamol CM3 Mesh or CM8 with appropriate plugs/tapes. Finish with plaster, render on mesh, or independent stud/board systems.
• Floors/basements: Use CM8 (studs-down) integrated with perimeter channels, discharging to a sump & pump where designed.
• Key principle: Provide a managed pathway for moisture and protect internal finishes from salts and damp contact.

9. Preventing damp returning

• Maintain gutters, downpipes, flashings and pointing; check after storms.
• Keep ventilation systems working; clean filters and vents regularly.
• Retain consistent background heat in colder months.
• Monitor at-risk rooms (bathrooms, kitchens, bedrooms) and act early on condensation.

10. Wykamol product routes (selection guide)

• Diagnosis & prep: Biocidal mould wash; salt neutraliser where specified.
• Rising damp: Wykamol Damp-Proofing Injection Cream; compatible DPC accessories.
• Penetrating damp (internal isolation): Wykamol CM3 Mesh / CM8 membranes with plugs, tapes and profiles.
• Basements/Type C: Wykamol CM8, perimeter channel, Wykamol sump & pump kit (as designed).
• Condensation & mould: Wykamol anti-mould treatments and compatible thermal/anti-condensation finishes.

11. Product availability

All materials referenced in this guide—Wykamol membranes (CM3 Mesh, CM8), Wykamol Damp-Proofing Injection Cream, plugs, tapes, profiles, anti-mould treatments, and sump & pump components—are available directly from Clever Shield Coatings. Use the site search bar or browse our product categories to find what you need.

12. Aftercare & monitoring

• Check repaired building elements periodically (gutters, pointing, seals).
• Allow replastered/finished areas to dry fully before decoration.
• If symptoms persist or recur, seek a competent re-inspection to verify the original diagnosis.