Penetrating Damp
The Dangers of Penetrating Damp
Rainwater entering a building through the roof or exterior walls is called penetrating damp; masonry and brickwork have to endure harsh weather conditions, with driving rain and gale-force winds and should your London home fall victim to penetrating damp, you need to take immediate action to limit the damage. The damp UK climate is an ideal breeding ground for penetrating damp and with increased rainfall, London is wetter than ever, which is not good news for homeowners.
We have been providing industry-standard damp surveys for London homeowners for 40 years, a family-managed business that offers independent damp inspections by qualified damp specialists and sourcing the causes of penetrating damp is one of our specialities.
The Damp London Climate
London sits on the Thames Valley Basin, a large area with a clay-based foundation and that means moisture retention. Heavy rainfall is a prime cause of penetrating damp; a leaking roof or walls allows rainwater into the building, which can cause extensive damage to masonry, plaster and timber. Regular inspections are advised in order to detect damp issues and when a building is compromised, there may not be any immediate signs.
Above Average Rainfall
Ask anyone in the London area about rain and they will agree that rainfall seems to be higher than usual. If you haven’t had your roof inspected recently, perhaps now is a good time to book an independent damp survey and find out if your home is impacted by penetrating damp. Blocked guttering, for example, can lead to rainwater running down exterior walls and if this is not addressed, the damp will penetrate to the interior walls.
Tell-Tale Signs of Penetrating Damp
The tell-tale signs include the following:
- Patches of damp on internal walls that do not dry out
- Plaster/paint deterioration
- Salt stains on walls, tide marks
- Rotting timber
- Damage to skirting boards and window frames
- Mould on internal decorations and fittings
- Musky odour in the house
- Moss growing on external walls
Watermarks on internal walls are a sure indication of penetrating damp and if you should notice any of the above signs, contact us on 020 8945 5547 and book an independent damp survey to get a definitive answer. We provide the homeowner with a detailed report within 24 hours of the survey completion. Should remedial work be required, we have a close working relationship with one of London’s leading damp-proofing companies.
Typical Causes of Penetrating Damp
Penetrating damp can be caused by the following:
- Driving rain can penetrate brickwork, masonry and compromised render
- Blocked guttering and downpipes
- Leaking roof
- Leaking window and door frames
Damp-proofing must be completed before repairing damage caused by penetrating damp, otherwise, the problem will persist.
How to Treat Penetrating Damp
Penetrating damp can be caused by compromised cavity wall construction and might require a DPC foam to be injected into the cavity and the application of waterproof render. A comprehensive roof inspection is advised if you notice signs of penetrating damp, which is one part of our independent damp survey package.
Penetrating Damp Treatments
The following are used to combat penetrating damp:
- Removal of damaged plaster/timber
- Use of salt neutraliser
- Tanking slurry
- Use of waterproof render
- Application of new waterproof exterior render
- Sealing external walls with clear silicone
The most important factor is to pinpoint the origin of the moisture penetration, then the remedial work can be done and after that, the damp damage can be repaired. If you repair damage caused by penetrating damp without first identifying the cause, you could be wasting your money, as the damage will return if the penetrating damp issue is not resolved.
How to Book an Independent Damp Survey
If you would like to book an independent damp survey from a leading London provider, we are the go-to company in all London Boroughs. Our PCA-certified surveyors use cutting-edge digital tools and equipment to accurately determine the presence of damp, mould and timber rot.
Call 020 8945 5547 or fill in the online form on this website and we will arrange for one of our certified damp surveyors to inspect your London home.
These two terms are often mixed up. Rising damp comes from the ground, if moisture enters a building from the roof or external walls, it is known as penetrating damp. Both are equally destructive and you can waste money if the damp is misdiagnosed.
The common signs of penetrating damp include damp patches and tide marks on walls and ceilings, moss growth on external walls signifies a source of moisture and this needs further investigation. If you notice a musky smell in the house, or bubbling paint and peeling wallpaper, this is a sure sign that damp is present. You can book an independent damp survey with London Damp Specialists and find out whether or not your home has damp, mould or timber rot issues.
Climbing onto a roof presents danger and we would never recommend that a homeowner do this. We provide an independent damp survey that includes a thorough roof inspection; our surveyors operate drones to get a close-up view of every square inch. They can see the guttering, examine the timber fascia and soffit boards and upper walls can be inspected, looking for signs of penetrating damp. You could book a roof inspection from a local roofing company but that would not include a damp survey on the whole house.
Damp Survey Costs
Transparent pricing with no hidden fees for our independent, unbiased surveys.
Level 1
What’s included:
- Inspection of walls
- Inspection of floors
- Inspection of ceilings
- Leak inspection of drains and plumbing
- Damp information and prevention guide
Level 2
What’s included:
- Everything in Level 1
- Dry rot inspection
- Wet rot inspection
- Woodworm inspection
- Damp information and prevention guide
Level 3 (Most Popular)
What’s included:
- Thermal Imaging
- Air humidity testing
- HD boroscope camera
- Brickwork pointing inspection
- DPC inspection
- Ventilation flow test on extractor fans
- 4K drone imagery roof, chimney stack
and guttering inspection - Structural condition inspection
- Inspection of walls
- Inspection of floors
- Inspection of ceilings
- Leak inspection of drains and plumbing
- Dry rot inspection
- Wet rot inspection
- Woodworm inspection
- Damp information and prevention guide
Survey Add Ons
Add On 1
Laboratory analysis Of plaster identifies hygroscopic salts such as chlorides and nitrates. which indicate whether damp is caused by rising groundwater or by plumbing leaks, This testing removes guesswork, allowing the exact source of moisture to be identified so the correct treatment is applied rather than carrying out unnecessary damp-proofing work.
Add On 2
qPCR DNA mould testing detects microscopic mould spores that are invisible during a normal inspection and van remain hidden behind walls, floors. or inside building rkaterials. It identifies the exact mould species present and the contamination level, allowing hidden mould problems to be confirrned and properly treated before they affect the property or occupants’ health.
Qualifications: All our surveyors are PCA and CSRT qualified for remedial treatments and also CSSW qualified for structural waterproofing.
Next day report: You will receive the report within 24 hours of the inspection taking place.
These are the tools we use
Damp Meter
A damp meter is a diagnostic tool used to detect and measure moisture levels within building materials such as plaster, brick, timber, and concrete.
Borescope camera
borescope camera is a small inspection camera attached to a flexible semi-rigid cable that allows you to see inside areas that are otherwise inaccessible.
Drone Inspection
A drone is a remotely operated aerial device equipped with a camera that allows visual inspection from above without the need for scaffolding or ladder.
Air Humidity Sensor
Air humidity sensor measures the amount of moisture present in the air, expressed as relative humidity (RH) in percentage. It helps determine whether indoor conditions are contributing to condensation, mould growth, or damp-related issues.
Thermal Imaging Camera
A thermal imaging camera detects temperature differences on surfaces by using infrared technology to produce a heat map image. In damp investigations, it helps identify cold spots, moisture intrusion, insulation defects, thermal bridging and leaks.
Air Flow Ventilation Detector
An air flow ventilation detector measures the movement and volume of air passing through vents, extractor fans, and air bricks. It confirms whether ventilation systems are working properly and achieving adequate air changes within a room. Poor airflow leads to trapped moisture, high humidity, condensation on cold surfaces, and ultimately mould growth.
Mould Lab Swab Testing
A mould swab test is carried out to confirm the presence of hidden mould growth and identify the specific species involved. Surface mould is not always visible, especially behind furniture, inside cavities, or within ventilation systems. Laboratory analysis of a swab sample determines whether active mould spores are present and what type they are, which helps assess potential health risks and decide the correct remediation approach rather than relying on visual assumption alone.
Lab Analysis of Plaster
Laboratory analysis of plaster is used to identify the type of salts present within the material, typically chlorides and nitrates. The presence and concentration of these salts help determine whether the moisture source is consistent with rising damp, ground contamination, or another forms [sic] of water ingress. such as mains water leak, This removes guesswork and prevents misdiagnosis, ensuring the correct remedial treatment is specified rather than applying unnecessary or ineffective solutions.
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