Understanding Cavity Membrane Systems and Their Functionality
There are many ways to damp proof buildings and in this article, we take a look at cavity membrane systems, which are generally used in basements, cellars and any below-ground structure.
How do cavity membrane systems work?
There are 3 main components to a cavity membrane system, namely:
- Cavity membrane – Made from High Density Polyethylene (HDEP), the membrane has studs to create a cavity between the walls and the membrane. Water is then directed into the drainage channels on the floor, keeping the walls and floor dry.
- Drainage channels – Placed at the base of walls, these channels divert water to designated discharge points.
- Pump system and sump – The pump is located near the drainage channels and removes the water, sending it to the drainage system. The sump chamber holds the water until it is pumped clear of the building.
Floor and wall membranes are different, with the floor membrane usually having a wider gap than wall membranes, which allows large volumes of water to escape the space. The cavity between the interior walls and the substrate should be large enough to accommodate water and if installed correctly, this should be sufficient to keep the interior dry.
Basement tanking
This term is used for basement or cellar waterproofing and a type C cavity membrane system is a very effective way to waterproof a basement or cellar. We do not recommend that you carry our basement tanking yourself, as it is specialised work that should be done by an experienced team; at London Damp Specialists, we are experts at all forms of waterproofing, especially basement tanking. If you would like a professional assessment and a quote, call us on 020 8528 3864 or fill in the form on our website.
Tailored to the property
Every basement is unique and the waterproofing should be designed around the space; there are several basement tanking systems and a specialist would choose the most suitable. Our work is of the highest standard, which is why we offer an unconditional 30-year warranty; in the event a treated area has further damp issues, we will repair this at no cost to the customer.
Climate change
The weather is no longer predictable, especially here in London and the southeast where we seem to have endless days of cloudy, wet weather. This means there is a higher risk of damp issues in London properties and if you are seeing signs of moisture in your below-ground living space, we offer comprehensive basement wall moisture protection and what’s more, we issue a full 30-year guarantee on our basement tanking in London and surrounding areas.
Homebuyer damp survey
Those who are planning to buy a London property that has a basement should call us on 020 8258 3864; we can carry out a thorough basement damp assessment, as well as inspecting the rest of the property looking for tell-tale signs of moisture penetration. The only way to be sure that a property is free from damp and mould is to carry out a thorough damp survey, which could save you thousands of pounds in damp repairs.
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:
- Everything in Level 1 & Level 2
- 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
- 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.
The survey fee will be deducted from the cost of any recommended repairs.
These are the tools we use
A 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.
Inspection Drone
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 Swab Test Kit
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.
Plaster Salt Analysis Lab
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.
Contact Us
If you have some questions, please complete this form:
Book and Pay for a survey
If you are ready to book a survey and pay, please complete this form:
Contact Us
If you have some questions, please complete this form:
Book and Pay for a survey
If you are ready to book a survey and pay, please complete this form:
Contact Us
If you have some questions, please complete this form:
Book and Pay for a survey
If you are ready to book a survey and pay, please complete this form: