A damp proofing solution is generally required when there are signs of rising damp include a musty smell, damp patches on walls, peeling paint, and crumbling plaster, often at the base of the walls. While some minor damp issues can be addressed with DIY methods, it’s recommended to seek professional help for significant damp problems to ensure proper treatment.
A well-installed damp proof course can last the lifetime of the building. However, it should be inspected regularly, and any damage or degradation should be repaired promptly. The cost of damp proofing varies depending on the severity of the problem and the method used. It’s best to get quotes from multiple professionals to get an accurate estimate.
Quick Answers
How do you treat damp walls internally?
Fix the moisture source first, remove damaged plaster, apply a damp proof membrane, then re-plaster using moisture-resistant materials.
Can you paint over damp walls?
Not safely. Walls must be fully dry, sealed with a damp primer, and painted with moisture-resistant paint.
What causes damp in homes?
The three main causes are:
- Rising damp (from the ground)
- Penetrating damp (through walls or roofs)
- Condensation (poor ventilation)
Do I need a damp specialist?
If the issue keeps returning, spreads, or affects structure—yes. DIY fixes won’t solve the root cause.
Welcome to Our Help & Advice Hub
Damp and mould problems are frustrating. They damage your home, affect your health, and often come back if treated incorrectly.
This page is your starting point.
Instead of overwhelming you with theory, we’ve broken everything down into simple guides you can follow—whether you’re:
- A homeowner trying to fix damp
- A tenant dealing with mould
- Or preparing a property before selling
👉 Use the guides below to find the exact help you need.
🔎 Find the Right Guide
Damp Problems Explained
🧱 How to Treat Damp Walls
🏠 Damp Surveys & Diagnosis
💨 Ventilation & Condensation Control
🧰 Damp Proofing Solutions
⚖️ Tenants’ Rights (UK)
Understanding Damp (Without the Jargon)
Most damp issues fall into three categories:
1. Rising Damp
Moisture travels up from the ground through brickwork.
Common signs:
- Tide marks on walls
- Crumbling plaster
- Damp at skirting level
👉 Usually requires a damp proof course (DPC).
2. Penetrating Damp
Water enters from outside due to defects.
Common causes:
- Cracked walls
- Faulty gutters
- Roof leaks
👉 Fixed by repairing the external structure first.
3. Condensation
The most common issue in UK homes.
Caused by:
- Poor ventilation
- Everyday moisture (cooking, showers)
👉 Solved with better airflow and ventilation systems.
How to Fix Damp Properly (Simple Process)
No matter the type of damp, the process is always:
- Find the source (don’t guess)
- Fix the cause (not just symptoms)
- Remove damaged materials
- Apply the correct treatment
- Improve ventilation to prevent return
Skip step 1 or 2, and the damp will come back.
Costs of Damp Proofing (UK Guide)
The cost of damp proofing varies depending on the severity of the problem and the method used. It’s best to get quotes from multiple professionals to get an accurate estimate.
Average damp proofing costs
| Damp proofing costs | Cost + VAT (low to high) | Average cost |
|---|---|---|
| Damp proof course cost | £250 to £2,000 | £850 |
| Damp proofing external walls cost | £750 to £2,500 | £1,500 |
| Damp proofing a cellar cost – tanking | £30 to £60 per square metre | £45 per square metre |
| Damp proof course injection cost | £1,000 to £5,000 | £3,500 |
*Prices vary depending on severity, access, and property type.
👉 Always get a proper survey before committing.
When to Call a Damp Specialist
You should get professional help if:
- Damp keeps returning after DIY fixes
- Walls feel cold and wet year-round
- You see mould spreading quickly
- Plaster is breaking down
- You’re buying or selling a property
Need Help With Damp in You London Home?
If you’re unsure what type of damp you’re dealing with, we can help.
At Damp & Mould Solutions Ltd, we’ve been resolving damp issues across London for over 15 years—focusing on accurate diagnosis, not guesswork.
👉 Book a damp survey or get expert advice today.
Damp problems don’t fix themselves—and quick fixes usually make things worse.
The key is simple:
Diagnose properly → treat correctly → prevent long-term.
Condensation Control
Installing proper ventilation systems like extractor fans and vents can significantly reduce condensation. Additionally, the use of dehumidifiers can help manage moisture levels in the air.
Do I Need to Remove Plaster Before Damp Proofing?
Removing plaster before damp proofing depends on the severity of the damp issue. If the plaster is contaminated with salts or mold, it should be removed to prevent further deterioration. However, if the plaster is in good condition, damp proofing can sometimes be applied directly over it.
How to Treat Damp Walls Internally
Treating damp walls internally involves several steps:
- Identify and Fix the Source: Before applying any treatment, ensure that the source of the dampness is addressed.
- Remove Damaged Materials: Remove any affected plaster, paint, or wallpaper.
- Apply Damp Proofing Membrane: Use a damp proof membrane to prevent moisture from seeping through the walls.
- Re-plaster: Re-plaster the walls with a moisture-resistant plaster.
