Rising Damp Treatment in London
A tide mark on internal walls, crumbling plaster, salt deposits, and a persistent damp smell at low level — these are the classic signs of rising damp. When present, it requires a properly installed chemical DPC and specialist replastering. We provide both, with a 20-year written guarantee.
Understanding the problem
What Is Rising Damp — and Why Does It Happen in London Properties?
Rising damp is the upward movement of groundwater through masonry walls by capillary action — the same process that draws water up a paper towel. It is most prevalent in London’s Victorian and Edwardian housing stock, where properties were built before damp proof courses became standard, or where an existing DPC has failed.
Properties built before 1875
Victorian and earlier properties were built without any damp proof course. Groundwater rises freely through solid brick walls by capillary action, typically reaching 1–1.5 metres in height.
Failed or bridged DPC
Properties built with a slate or bitumen DPC may develop rising damp if the course deteriorates with age, or if soil, render, or a patio has been raised to bridge above the DPC level externally.
High external ground levels
Where paths, gardens, or neighbouring properties have raised the external ground level above the existing DPC, moisture bypasses the barrier and enters the wall structure at the elevated level.
Why accurate diagnosis matters
Rising damp shares visible symptoms with penetrating damp and condensation. Incorrect diagnosis leads to the wrong — and often expensive — treatment. CSRT-certified moisture surveys distinguish accurately between causes.
20-Year Written Guarantee on All Rising Damp Treatment
All rising damp treatment carried out by Damp & Mould Solutions is backed by a 20-year written guarantee covering the chemical DPC and associated replastering. No hidden conditions, no annual inspection requirements, transferable on property sale.
Do you have rising damp?
Signs Your Property Has Rising Damp
These are the distinctive symptoms of genuine rising damp — as opposed to penetrating damp or condensation. If you’re seeing several of these together, a CSRT moisture survey is the reliable way to confirm the cause before committing to treatment.
Consistent Tide Mark at Low Level
The most diagnostic sign of rising damp is a horizontal tide mark — typically between 0.5 and 1.5 metres — on internal walls at low level. Unlike penetrating damp (irregular height) or condensation (highest points), rising damp produces a fairly consistent band that follows the height water has reached within the wall.
- Mark consistent across the full width of the wall
- Height of 0.5–1.5 metres — characteristic of capillary rise
- Often more visible in winter when evaporation is lower
Salt Staining & Efflorescence
As rising damp evaporates from the wall surface, it deposits salts from the ground within the plaster and on the surface. These hygroscopic salts appear as white powder or crystalline deposits and are strongly associated with rising damp rather than condensation or roof/plumbing leaks.
- White powdery deposits — ground salts deposited at evaporation point
- Frothy or granular plaster texture — salt crystallisation within substrate
- Presence of nitrates in analysis — confirms groundwater origin
Crumbling or Hollow Plaster at Low Level
Plaster that has been saturated with moisture and contaminated with hygroscopic salts loses its structural integrity. It sounds hollow when tapped, crumbles at the edges, and detaches from the wall substrate. This contaminated plaster must be removed and replaced — it cannot be salvaged once salt-saturated.
- Hollow sound when tapping — lost bond with substrate
- Crumbling edges or soft spots — structural breakdown
- Plaster falling away from walls — salt crystallisation delaminating
Persistent Damp Smell at Low Level
Rising damp produces a characteristic musty, earthy smell — particularly noticeable in rooms with little ventilation, in hallways, and in rooms with solid external walls. The smell persists year-round unlike condensation smells, which are typically worse in cold weather. Ground salts and biological activity in moisture-laden plaster produce the odour.
- Persistent year-round — not seasonal like condensation
- Strongest at low level and near affected walls
- Not resolved by ventilation alone — source treatment required
Is it rising damp, penetrating damp, or condensation?
These three conditions share visual symptoms — damp patches, mould, and salt staining — but require completely different treatments. A chemical DPC injection on a wall affected by penetrating damp will not work. A CSRT-certified moisture survey using calibrated meters is the only reliable way to determine the cause and ensure the right treatment is recommended.
Call 020 4542 6114 to book a diagnostic survey →Our treatment process
How We Treat Rising Damp — Survey to Finished Wall
Rising damp treatment involves more than injecting a DPC — it requires resolving the external cause, installing the chemical barrier correctly, and replastering with a salt-resistant specification. We manage the complete process.
CSRT Moisture Survey
Calibrated moisture meters measure wall readings at multiple heights. Confirms rising damp and rules out penetrating damp or condensation before any treatment is proposed.
Resolve External Factors
High ground levels, bridged DPC, or defective drainage that allowed the DPC to fail are addressed before treatment — otherwise the problem recurs.
Chemical DPC Injection
Silane or siloxane cream or fluid injected under pressure into a horizontal mortar course at low level — BS 6576 specification. Creates a permanent moisture barrier within the wall structure.
Remove Contaminated Plaster
All salt-contaminated plaster stripped back to a minimum of 1 metre above the tide mark — removing hygroscopic salts that would cause the wall to appear damp again if left in place.
Salt-Resistant Replastering
Renovation plaster system applied to the treated wall — salt-retardant plaster designed specifically for post-DPC environments, not standard gypsum that would fail within months.
20-Year Guarantee
Written guarantee issued covering the DPC and replastering. Transferable on property sale. No annual inspection requirements or hidden conditions.
Complete solution
Services That Accompany Rising Damp Treatment
Rising damp treatment is rarely a standalone service — it always requires replastering with the correct specification, and where mould is present, remediation before the new plaster is applied. We manage the complete remediation.
Replastering With Salt-Resistant Systems
Rising damp treatment always requires removal of contaminated plaster and replacement with a salt-resistant renovation plaster system. Standard gypsum plaster applied after DPC injection will fail — hygroscopic salts in the substrate cause it to deteriorate within months.
- Renovation plaster specified for post-DPC environments
- Full plaster removal to 1 metre above tide mark
- Included as standard in our rising damp packages
Damp Survey
A CSRT-qualified damp survey correctly identifies whether the cause is rising damp, penetrating damp, or condensation — or a combination. Misdiagnosis leads to the wrong treatment. Pre-purchase surveys available for buyers across London.
- Calibrated moisture meters — not visual assessment alone
- Written report with photographic evidence and recommendations
- Pre-purchase surveys available — same-week where required
Mould Removal
Rising damp creates the moisture conditions for mould growth on plaster and timber skirting boards. Where mould is present, it must be professionally remediated and the substrate treated with biocide before new plaster is applied — sealing mould behind new plaster produces ongoing contamination.
- Anti-fungal biocide treatment to substrate
- Coordinated with DPC installation — single visit where possible
- Air quality monitoring available for severe mould cases
Penetrating Damp Treatment
In some London properties — particularly Victorian terraces with solid brick construction — rising damp and penetrating damp coexist. Where moisture survey readings indicate both, we treat both in a coordinated package rather than leaving one unresolved.
- Comprehensive survey identifies all active moisture sources
- Combined treatment package where multiple causes present
- 10-year guarantee on penetrating damp treatment
London coverage
Rising Damp Treatment Across London
Rising damp is concentrated in London’s pre-1920 housing stock — Victorian and Edwardian terraces and semis, period conversions, and basement flats. We work across all London boroughs, with particular experience in North and North West London’s period housing.
Not sure if it’s rising damp or another cause? Call 020 4542 6114 — we’ll advise based on what you’re seeing before the survey visit.
Common questions
Rising Damp Treatment FAQ
What is rising damp?
How do you treat rising damp?
Is rising damp often misdiagnosed?
How long does rising damp treatment last?
How much does rising damp treatment cost in London?
What our customers say
Trusted by London Homeowners & Landlords
We had serious rising damp and mould in our Victorian terrace. These guys were brilliant — professional, tidy, and sorted it all within days. Walls are dry and the finish is excellent. Highly recommend.
Another company told us we had rising damp throughout the ground floor. Damp and Mould Solutions surveyed properly and found it was actually penetrating damp from failed pointing on one wall. Saved us thousands by diagnosing correctly.
Pre-purchase survey identified rising damp and they treated it before we exchanged. The 20-year guarantee was important for our lender. Great service throughout — thorough survey, clear report, and quality workmanship.
Get in touch
Book a Rising Damp Survey in London
Speak to a CSRT-Qualified Damp Specialist
Tell us what you’re seeing — the height of the tide mark, which walls are affected, and whether salt deposits are present — and we’ll advise on likely cause before the survey visit. Same-week appointments frequently available across London.
💡 Tip: A photo of the affected wall — showing the height of the tide mark and any salt deposits — sent to info@dampandmouldsolutions.co.uk helps us advise on likely cause before the visit.
Request a Rising Damp Survey
Fill in your details — same-week appointments frequently available across London.
Don’t Let Rising Damp Spread Further Up Your Walls
Rising damp is progressive — without treatment, moisture migrates higher and causes more structural damage, more contaminated plaster, and greater repair costs. A same-week survey costs far less than the damage caused by delay.