London Homebuyer Damp Checklist – Important Factors to Consider Before Purchase

London Homebuyer Damp Checklist – Important Factors to Consider Before Purchase

3rd July, 2025

If you are planning to invest in a London property, you have come to the right place, as we present essential information about damp and mould issues. Property prices are the highest in the country in London and rather than taking it on face value, you need to ensure that the building is not compromised by damp or mould.

Here is a damp checklist to help you discover whether or not a property has damp or mould issues.

  • Inspect the roof – A leaking roof is definitely a source of moisture entering the interior roof structure. Imagine a few roof tiles being lifted off the roof during gale force winds; the chances are you would not be aware of this and a few heavy rain showers is all it takes to let water into the internal roof structure and that would cause damage to joists and rafters. Another potential issue is blocked roof guttering, as this would result in excess rainwater running down the exterior walls. If you book a damp inspection with London Damp Surveys, a comprehensive roof inspection is included.
  • Inspect exterior walls – Damp can penetrate exterior walls if brickwork, masonry or rendering is compromised; use a screwdriver to poke masonry and mortar to test the integrity of the material. Check the walls at ground level to see if rising damp is present, which can be the result of damaged damp proof course, which is sandwiched between brick courses to prevent moisture rising up the exterior walls. Often, the best solution is to inject a chemical damp-proofing material that sets and prevents moisture rising.
  • Condensation – This can cause a lot of damage to a building; caused by excessive moisture in the air, condensation can form on walls and windows and it should be wiped up with a dry cloth. Of course, you need to get to the underlying cause of condensation, which might be lack of ventilation or penetrating damp and the best way to do this is to commission a damp inspection from London Damp Surveys; we cover all London Boroughs and our team of qualified damp surveyors are always ready to assess your home.
  • Inspect interior walls – Start with the upstairs, looking for damp patches, peeling wallpaper or bubbling paint. If you see tidal marks, this is an indication that water was present and has dried out. Check the ground floor walls and ceilings for signs of damp and should you find signs of moisture, it needs to be investigated.

If you are planning to make an offer on a London property, don’t take any chances, call London Damp Surveys on 0207 305 5997 during regular office hours or fill in the form on this website. Our qualified damp surveyors use state-of-the-art equipment to inspect a building and if damp, mould, woodworm or condensation are present, our surveyor will find it and you will receive a detailed report shortly after the survey completion.

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.

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.