Damp walls aren’t just unsightly—they can damage your home and health. This guide will help you understand the causes, spot the signs, and take practical steps to treat damp walls properly.
What Causes Damp in Walls?
There are three main types of damp:
1. Condensation
- Most common in bedrooms, bathrooms, and kitchens
- Caused by warm air hitting cold surfaces
- Signs: Water droplets on windows, black mould in corners, musty smells
2. Rising Damp
- Happens when moisture rises up from the ground
- Caused by a broken or missing damp proof course (DPC)
- Signs: Tide marks, peeling wallpaper, cold lower walls
3. Penetrating Damp
- Caused by water entering from outside
- Common with damaged bricks, poor render, or leaking gutters
- Signs: Damp patches after rain, mould on high walls, staining
Step-by-Step Guide to Treat Damp Walls
Step 1: Identify the Source
- Walk around your home.
- Inside: Look for mould, stains, or flaking paint.
- Outside: Check brickwork, gutters, roof tiles.
Step 2: Fix the Cause
Condensation Fixes:
- Open windows daily
- Use extractor fans
- Avoid drying clothes indoors
- Add a dehumidifier or PIV system
Rising Damp Fixes:
- Inject damp proof cream
- Fit a damp proof membrane
- Lower external ground levels below the DPC
- Replaster with salt-resistant render
Penetrating Damp Fixes:
- Repair gutters and downpipes
- Seal cracks in bricks or render
- Reseal windows and doors
- Apply masonry cream
Step 3: Treat the Internal Walls
Replastering:
- Use breathable, damp-resistant render—not standard plaster
Damp Proof Paints:
- Only apply on dry, clean walls
- Avoid painting over salt-contaminated areas
Tanking Slurry:
- Great for basements
- Creates a waterproof barrier on internal walls
Treating External Walls
- Use masonry cream to repel water
- Repair render or pebbledash
- Keep gutters and roof in good condition
- Avoid planting trees/shrubs near walls
Treating Damp in Bedrooms and Living Rooms
- Keep furniture slightly away from walls
- Ventilate after showers or cooking
- Heat rooms evenly
- Consider insulating cold walls
How Moisture Meter Readings Help
Use a moisture meter before treating walls.
What’s Normal?
- 12%–15% is typical for internal walls
- 16%+ suggests a problem
Moisture Reading Guide:
| Moisture % | Condition | Action Needed |
|---|---|---|
| 0–10% | Dry | No action required |
| 11–16% | Slightly Damp | Improve ventilation |
| 17–20% | Moderately Damp | Investigate the source |
| 21–25% | Damp | Take action |
| 26%+ | Very Damp | Call in professionals |
DIY or Call a Professional?
- Minor condensation? Try DIY solutions.
- Rising or penetrating damp? Get expert help.
FAQs
Q: How to stop moisture coming through walls? A: Find the source—condensation, rising or penetrating damp—then treat it at the root.
Q: How do you damp proof an internal wall? A: Inject cream, use membranes, and replaster with water-resistant render.
Q: How to treat walls before painting? A: Dry the wall, remove loose material, treat salts or mould, prime, then paint.
Q: How do you permanently fix damp? A: Solve both the cause and the damage. Fix leaks, damp proof, and replaster.
Q: Can I treat damp walls myself? A: Yes, if it’s minor. But call experts for rising damp or structural issues.
Final Tips
- Ventilate year-round
- Inspect gutters and roofs seasonally
- Keep external ground below the DPC line
- Don’t ignore mould or musty smells
Need Expert Help?
Don’t let damp take hold. At Damp and Mould Solutions Ltd, we find the cause and fix it right.
📞 Call: 020 4542 6114
📧 Email: [email protected]
Let’s make your home dry, healthy, and stress-free.