Damp Proofing

What Affects the Cost?

• •Type of damp (rising, penetrating, or condensation)
• •Number of walls and area affected
• •Whether replastering is needed after treatment
• •Basement tanking vs DPC injection
• •Access to external walls

Areas We Cover

Frequently Asked Questions

What are the different types of damp?

The three main types of damp in London properties are rising damp, penetrating damp, and condensation. Rising damp occurs when groundwater travels upward through walls by capillary action, usually because the original damp-proof course has failed or was never installed — common in Victorian and Edwardian terraces built before 1920 across boroughs like Lewisham, Southwark, and Greenwich. It typically shows as a tide mark up to 1 metre high with salt deposits (efflorescence) and blown plaster. Penetrating damp enters through external walls, roofs, or around windows due to failed pointing, cracked render, or damaged flashings — we see this frequently in exposed south-west facing elevations. Condensation is caused by excess moisture in the air meeting cold surfaces, and is the most common cause of black mould in bathrooms and kitchens. Each type requires a fundamentally different treatment — we diagnose the cause using professional-grade moisture meters and thermal imaging cameras before recommending a solution.

How can I tell if my house has a damp problem?

Common warning signs include peeling or bubbling wallpaper, black mould growth (especially in corners and behind furniture where air circulation is poor), a persistent musty smell, white salt deposits (efflorescence) on walls, damp patches that feel cold to the touch, rotting skirting boards or window frames, and condensation regularly forming on windows during cooler months. In older London properties — particularly Victorian terraces built between 1850 and 1910 across South East London — damp is especially common at ground floor level where the original slate or bitumen damp-proof course may have deteriorated or bridged by raised external ground levels. Moisture readings above 20% on a protimeter-type meter generally indicate an active damp problem requiring treatment. We offer a free damp inspection where we use calibrated moisture meters and thermal imaging to diagnose the type and severity of the problem, then provide a written report with recommended treatments and a fixed-price quote.

Do you offer a guarantee on damp proofing work?

Yes, all our damp proofing treatments come with a written guarantee backed by both our company and the product manufacturers. Chemical DPC injection treatments using silicone-based cream systems from suppliers like Safeguard or Sovereign carry a 20-year guarantee as standard. Basement tanking systems using cementitious slurry coatings or cavity drain membranes are guaranteed for 10 years. External waterproofing and penetrating damp repairs are guaranteed for the expected lifespan of the materials used, typically 10-15 years depending on exposure. The guarantee covers both materials and workmanship, and we provide full documentation including a Property Care Association compliant certificate that you can pass on if you sell the property. This documentation is routinely requested by solicitors during conveyancing and by mortgage lenders during valuations, so having a properly guaranteed treatment from a reputable contractor adds measurable value when you come to sell and avoids potential issues with property transactions.

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