What is the Difference Between Rising Damp and Penetrating Damp?
This is a question that many of our customers ask and in this short article, we explain how rising and penetrating damp differ, along with typical solutions.
As the name implies, we are talking about moisture that rises up from the ground when we mention the term ‘rising damp’. Buildings need a damp proof course to prevent moisture from attacking the structure; damp passes through most materials with capillary action, much like a sponge soaks up water and if not addressed, the moisture will continue to spread. Older London homes typically have a black layer of DPC that is bitumen-based and impervious to water, which can easily be damaged by ground subsidence. Our independent damp survey includes a thorough inspection of the DPC and we look for tell-tale signs such as damp patches on internal walls and moss growth outside.
Solutions
Often, the best solution is to inject a chemical foam into the wall cavities, which acts as a moisture barrier and also provides excellent thermal insulation, which reduces or removes condensation. The original DPC can be repaired in some cases; we work closely with the best damp-proofing company in London and they guarantee their work for a full 30 years.
Penetrating Damp
Moisture that enters a building from the roof or external walls is called penetrating damp, because it eventually penetrates into the interior, damaging timber and plaster. The mastic that seals timber window and door frames can be compromised and this would allow rainwater to penetrate the frame and cavity wall. The passing of time sees the damage slowly spread and if a house is unoccupied and there is a damp issue, the results can be devastating. Condensation is a tell-tale sign of penetrating damp and our condensation experts can come up with a solution.
Solutions
The most important thing to do is find the source of the moisture and fix it; only then can you think about damp damage repair. We offer an independent damp survey that covers every aspect of damp, mould and timber rot; we use cutting-edge digital devices to pinpoint damp and you receive a detailed report in your inbox the following day. While we do not provide damp-proofing services, we work closely with the best damp-proofing company in London; they issue a 30-year warranty on all damp-proofing work.
The Importance of Regular Damp Inspections
The only way to be sure that your London home is free from damp and mould is to book an independent damp survey from a reputable company such as London Damp Specialists. You can call us on 020 7205 4886 or leave a message in the online form and we will get back to you.
Pre-Purchase Damp Survey
It is not difficult to conceal damp damage; a coat of paint here and a skim of plaster there and the average person would be none the wiser. Be sure that the property is free from damp and mould by booking an independent damp survey with a company that has been providing a top-rated service for more than 40 years.
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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