Basement Waterproofing in London Homes – What You Need to Know
A large number of London homes have a basement; some use this below-ground space for storage, while others turn it into living space; the property owner might decide to make the basement a 1 bedroom flat, which they rent out for a regular income. Then there are a few London houses that have extra floors to greatly increase the living space by building huge underground rooms.
High water table
London is also a wet, low-lying region with a bed of clay and this means damp can attack basements and cellars. There are specialised companies that offer basement tanking in London and they have more than 40 years of hands-on experience waterproofing basements. Such a company would offer a full 30-year guarantee on their work.
Basement tanking
This involves the use of waterproof plaster and render; the basement is emptied of all items and the damp-proofing team remove all damp plaster and the substrate is cleaned and dried. The ceilings are also cleaned and prepared, then the first coat of water-resistant plaster is applied and allowed to dry completely before another coat is added. When this coat is dry, a final skim of plaster is added and that should keep the interior dry at all times. The flooring also needs to be treated with waterproof render and screed, then the space can be used in any way you prefer.
Cavity drainage system
This is a system that is very effective at waterproofing basements; first, remove all plaster (damaged and undamaged) from all ceilings and walls, then prepare the substrate for fixing the cavity membrane, which is studded to create a space behind the wall. The studded membrane is also fitted to ceilings, as well as the walls, while channels are created under the flooring, with a sump and pump to channel water to the designated drainage points. Essentially, this system isolates the interior from the exterior by creating a cavity for the water to run down into the floor channels. Even very wet areas can be waterproofed using this method, making it very effective in wet areas where waterproof plaster is inadequate. An average-sized basement might take 3-4 days to waterproof and when everything is dry, you can bring in the furniture and the space is ready for occupation. The damp-proofing company are so confident in their work that they issue a no-quibble 30-year guarantee; if damp returns, they will fix it at no cost to the customer.
Independent damp survey for basements
If your basement is not waterproof, it is time to contact London Damp Specialists and book an independent damp survey of your underground living space. Our certified damp surveyors are very experienced and they can quickly pinpoint the origins of moisture that enters the space. The inspector can recommend the best solution to keep your basement dry at all times, plus we can recommend the best basement tanking contractor in London to carry out the work.
Don’t take any chances when it comes to damp and mould, contact London Damp Specialists on 020 7205 4886 or complete the survey booking form in this website.
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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