Top Causes of Basement Flooding and How to Prevent It

If you are lucky enough to have extra living space in the form of a basement, flooding is a very real possibility for every sub-ground level space. Here at London Damp Specialists, we have a wealth of experience in dealing with basement flooding and in this short blog, we present common causes of basement flooding and ways to prevent moisture from entering the structure.

  • Blocked guttering – If the guttering is blocked with moss and wet leaves, excess rainwater will run down the exterior walls and collect at the ground level. Clogged downpipes can also cause water to seep underground, which would damage a basement if not immediately addressed.
  • Compromised sealant – There are several sealants that are used to waterproof a basement at ground level; older properties are more likely to encounter this issue and a thorough damp proofing test from one of our technicians would quickly reveal the cause and repairs can be done. We offer a basement tanking service that makes the cellar walls waterproof, keeping moisture out.
  • Sloping ground – If a portion of your garden slopes toward the house, this could mean that water does not drain away, rather it gathers at the property line and this moisture can penetrate the basement walls, causing a lot of damage.
  • Mains water leak – You could be losing water without realising it and a leaking pipe under the garden can lead to dampness penetrating your basement and the foundations of the house. A typical sign would be an area of the lawn that is greener than the rest, due to the constant seeping of water. Give us a call and we can test your basement for signs of moisture damage, then we can draw up a list of actions that solve the problem.
  • Backed up sewers – In the event a sewer clogs, this could result in flooding, not just in the basement, but above ground too. This could be classed as a major disaster, which is one reason why you should have your drains power flushed on a regular basis. A drain unblocking specialist would use CCTV technology to get a close-up view of the drains, then they can carry out the unblocking.

If you have a basement and you are worried about flooding and water damage, call in a London-based specialist for basement tanking, which is a way to waterproof a basement. As basements are below ground level, moisture from the surrounding soil can easily cause damage; we at London Damp Specialists offer a total waterproofing solution for basements and cellars that involves adding a waterproof membrane to the floors, walls and ceilings.

Call us today on 020 8528 3864 and let the basement tanking experts protect your property, we have the know-how and the resources to come up with a complete solution. We also carry out damp surveys to determine the precise situation and come up with a workable solution that protects your property from water damage.

Damp Survey Costs

Transparent pricing with no hidden fees for our independent, unbiased surveys.

Level 1

Level 1

£199 + VAT

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

Level 2

£299 + VAT

What’s included:

  • Everything in Level 1
  • Dry rot inspection
  • Wet rot inspection
  • Woodworm inspection
  • Damp information and prevention guide

 Survey Add Ons

Add On 1

£299 + VAT
Lab Analysis Of Plaster

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 to Survey

Add On 2

£299 + VAT
Mould Lab Swab Testing, qPCR on DNA

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.

Add to Survey

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

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

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

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

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

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

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

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

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: