Dry Rot Treatment Across London & Surrey
Dry rot spreads fast and travels through masonry. Expert diagnosis and eradication — act now.
What is Dry Rot?
Dry rot (Serpula lacrymans) is the most destructive timber decay organism found in buildings. Unlike wet rot fungi, dry rot can produce extensive mycelial growth that spreads through masonry, mortar, plaster and other non-timber building materials in search of new timber to attack. A localised outbreak that is not treated can spread through an entire building.
Despite its name, dry rot requires moisture to grow — it simply requires less moisture than wet rot fungi, surviving in timber with moisture content as low as 20–25% (compared to 50%+ for wet rot). Once established, it can generate moisture itself through its metabolic processes, enabling it to continue growing even in apparently dry conditions.
Dry rot can travel metres through masonry in search of new timber — a small outbreak discovered in one room may already have established throughout the floor structure or wall cavity. Professional investigation of the full extent is critical before any treatment.
Identifying Dry Rot
Cuboidal Cracking
The most distinctive sign: timber affected by dry rot cracks both along and across the grain, creating a characteristic ‘cuboidal’ pattern. The wood becomes lightweight, dark brown and crumbles easily.
Fruiting Bodies
Dry rot produces large, fleshy fruiting bodies (sporophores) that have a rusty-red centre surrounded by a white margin. They produce enormous quantities of rust-red spore dust.
Mycelium & Strands
Dry rot produces extensive grey-white cotton-wool-like mycelium and thick strand-like structures (rhizomorphs) that can travel significant distances through the building fabric.
Musty Smell
Active dry rot produces a distinctive musty, mushroom-like odour that is often detected before the fungus itself is visible — particularly in enclosed spaces like underfloor voids.
Rust-Red Spore Dust
Fine rust-red spore dust covering large areas of surfaces near a fruiting body is a classic indicator of active dry rot. The spores are highly resilient and can remain viable for years.
Lightweight Timber
Severely affected timber becomes extremely lightweight — the fungus breaks down the cellulose, leaving only a lightweight, brittle residue with no structural strength.
Our Dry Rot Eradication Process
Dry rot treatment requires a systematic, methodical approach that goes well beyond simply removing the visible growth:
- Full investigation — we trace the extent of the outbreak through the structure, opening up as necessary to confirm all areas of mycelium and affected timber. Treatment based only on visible growth frequently fails.
- Moisture source identification — dry rot cannot survive without moisture. Identifying and eliminating the moisture source is the first step in preventing recurrence.
- Removal of affected timber — all decayed timber is removed and disposed of as contaminated waste. Removal extends 500mm beyond the last visible signs of decay into apparently sound timber.
- Masonry treatment — all masonry and plaster in the affected area is treated with fungicidal solution by spray, brush and injection to kill residual mycelium within the structure.
- Replacement timber — new structural timber is pre-treated with preservative and installed. All end-grain and cut surfaces are treated on site.
- Environmental control — ventilation is improved and the moisture source is permanently resolved to ensure conditions cannot support regrowth.
- Monitoring — we recommend a follow-up inspection after the first heating season to confirm the treatment has been fully effective.
Is dry rot covered by buildings insurance?
It depends on your policy. Some policies cover dry rot caused by a specific insured event (such as a plumbing leak), while others exclude it as a maintenance issue. Our report will document the cause, which is essential for any insurance claim.
How quickly does dry rot spread?
Under favourable conditions, dry rot can spread rapidly — advancing several centimetres per week through timber and masonry. This is why immediate professional assessment on discovery is important.
Can I treat dry rot myself?
DIY dry rot treatment is rarely successful because the extent of the outbreak is almost always greater than what is visible. Partial treatment that misses areas of mycelium allows the outbreak to re-establish. Professional treatment with masonry injection and structural timber replacement is needed for reliable eradication.
Properties at Risk in London & Surrey
Dry rot is significantly more common in pre-1930 properties, which form the majority of housing stock in many London boroughs including Lambeth, Wandsworth, Croydon, Lewisham, Hackney and Islington. Victorian and Edwardian terraced houses typically feature suspended timber ground floors with sub-floor voids that, if inadequately ventilated or subject to moisture ingress, create ideal conditions for dry rot colonisation.
In Surrey, older properties in towns such as Guildford, Reigate, Redhill, Dorking and Farnham similarly feature the solid masonry construction and timber flooring that is susceptible to dry rot when moisture management fails. Ground-level damp caused by clay soils, aging drainage infrastructure and burst supply pipes from South East Water or Affinity Water mains are frequent triggers.
Any property that has experienced a plumbing leak, drainage overflow, roof failure or condensation problem over an extended period should be assessed for dry rot — particularly if there are enclosed timber structures such as floor voids, roof spaces or wall panelling.
Wet Rot vs Dry Rot — How to Tell the Difference
Wet Rot
- ✓ Localised — stays near moisture source
- ✓ Timber dark and fibrous
- ✓ Cracks along the grain
- ✓ Less likely to travel through masonry
- ✓ Easier to treat — eliminate moisture, replace timber
Dry Rot — Far More Serious
- 🚨 Spreads beyond moisture source
- 🚨 Travels through masonry and mortar
- 🚨 Cuboidal cracking pattern
- 🚨 Generates moisture itself
- 🚨 Requires masonry sterilisation + full replacement
Dry Rot Treatment Cost Guide
Treatment costs depend on the extent of the outbreak and the degree of structural timber replacement required. A small, contained outbreak discovered early may require only localised treatment. A large outbreak that has spread through floor joists, wall plates and masonry may require significant structural work. We provide detailed scope and costing after the initial investigation.
Early detection is the single most effective way to minimise dry rot treatment costs. A small, newly-established outbreak can be treated for a fraction of the cost of an advanced infestation. If you suspect dry rot, call us immediately rather than monitoring or attempting DIY treatment.
More Questions Answered
How do I know if I have dry rot or just mould?
Mould grows on surfaces and is usually green, black or white. It does not structurally damage timber and does not spread through masonry. Dry rot attacks the timber itself — the wood becomes brown, lightweight and crumbles when pressed. The distinctive cuboidal cracking pattern and musty mushroom smell are key indicators. If you are unsure, do not delay — call us and we will assess the situation, usually on the same day.
Does dry rot need to be disclosed when selling a property?
Yes. Sellers have a legal duty to disclose known material defects including active or historic dry rot. Failure to disclose can result in a claim for misrepresentation. Where treatment has been completed, a professional treatment report demonstrating that the outbreak has been eradicated and the moisture source resolved provides evidence for buyers and their solicitors.
What guarantees come with dry rot treatment?
Our dry rot eradication work comes with a written guarantee. The guarantee covers the treated areas against recurrence of the treated outbreak, subject to the moisture source having been resolved. Guarantees can be transferred to a new owner on sale of the property, making treated properties easier to sell and to mortgage.
Areas We Cover
We operate across South London, North London, East London and throughout Surrey — typically within a 20-mile radius of Cheam, SM3.
South London
- ✓ Croydon
- ✓ Sutton
- ✓ Merton
- ✓ Wimbledon
- ✓ Tooting
- ✓ Balham
- ✓ Clapham
- ✓ Streatham
- ✓ Lambeth
- ✓ Wandsworth
- ✓ Kingston
- ✓ Richmond
- ✓ Thornton Heath
Surrey
- ✓ Guildford
- ✓ Woking
- ✓ Epsom
- ✓ Leatherhead
- ✓ Reigate
- ✓ Redhill
- ✓ Dorking
- ✓ Camberley
- ✓ Farnham
- ✓ Staines
- ✓ Weybridge
- ✓ Esher
- ✓ Cheam
North & East London
- ✓ Hackney
- ✓ Islington
- ✓ Camden
- ✓ Haringey
- ✓ Walthamstow
- ✓ Stratford
- ✓ East Ham
- ✓ Ilford
- ✓ Romford
- ✓ Barking
- ✓ Lewisham
- ✓ Greenwich
Not sure if we cover your area? Call us on 0800 054 1524 — we’re happy to advise.
Ready to Get Started?
Surveys available across London and Surrey. Same-day attendance available.