PENETRATING DAMP

 ARE YOU CONCERNED THAT YOUR PROPERTY HAS PENETRATING DAMP?

Penetrative damp is simply rain water that seeps through the cracks in a building’s foundation, and it can impact both the structure of the building as well as the health of its occupants. This problem is most common in buildings that are exposed to excessive amounts of rainfall or in older buildings with blocked gutters or porous bricks and roofs with cracks.

Rain penetration, or penetrative damp as it’s also known, is caused by the movement of moisture, in a horizontal direction. Or by rain water seeping through the walls randomly. It can affect cavity walls or badly installed wall-ties, internal walls and buildings constructed with solid walls.
Penetrative damp is most commonly caused by the presence of porous bricks that allow water to permeate through the walls, or by defective buildings.

Damage ceiling from water pipelines leakage
Water-leakage-from-broken-pipe-behind-wall-causing-water-stains
damp survey

SIGNS THAT YOUR HOUSE HAS PENETRATIVE DAMP:

  • EDamp patches on internal walls that won’t go away, even after you’ve dried them
  • EThe paint / plaster on your walls are deteriorating
  • EYou see blisters, stains or salt deposits on the wall
  • EThe timber in your house is starting to rot or decay
  • EYour window frames / skirting boards rotting Mould growing on your internal decorations. You can smell dampness or mould in your house. Moss is growing on the external walls of your house

You can spot penetrative damp by watermarks or moist patches near windows or doors, at any height. The moisture detector will usually have high readings when it’s raining, but low readings when it’s dry. Don’t wait to fix the problem — call London Damp Specialist at 0207 305 5997 and get your survey booked in today!

THE CAUSES OF PENETRATING DAMP

Penetrating damp is often caused by blocked downpipes/gutters, or blown rendering. It is common for rainwater to penetrate the wall horizontally, causing penetrating damp. You must also check for damage, decay or cracks in window frames and roofs.

You must be protect external basement and retaining walls from moisture intrusion by using tanking treatments. Interior walls can be protected by a chemical damp-proof course and waterproof renders. If there are building defects, such as faulty windows or roofs, they must be rectified by proficient and professional builders.

TREATING PENETRATIVE DAMP

With recent advancements, penetrative damp treatment is even more sophisticated. If your internal walls suffer from poorly constructed cavity walls and installation of wall ties, you can use a damp proof render to fix the problem.

External walls often need to be treated with water-resistant paints and coatings, along with water repellent creams and fabrics. Clogged gutters and downpipes must occasionally be cleaned out, while cracked roof tiles should always repaired swiftly.

Colourless water repellents can be good as they are breathable and allow moisture to escape through them, rather than blocking it. Window sills and other areas where water is stored must be cleaned of dirt, leaves and moss growth regularly.

Cement tanking systems can be employed to effectively treat damp issues caused by high external ground levels.

Penetrating damp treatments could be:

  • NRemoving plaster
  • NTanking Slurry
  • NWater-proof render
  • NSalt neutraliser
  • NApplication of skim coat plaster
  • NApplication of an external render
  • NUsing a clear waterproof sealer on the exterior walls
  • There can be health implications associated with damp such as those caused by mould and dust mites, which can trigger allergies or aggravate pre-existing medical conditions.

PENETRATING DAMP CAN BE A SERIOUS PROBLEM IF LEFT

Thousands of homeowners have used London Damp Specialist. If you need a professional damp survey, book it today using our online form or by calling us directly on 0207 305 5997.

frequently asked questions

Can penetrating damp affect both internal and external walls?

Yes, penetrating damp can affect both internal and external walls. It occurs when water penetrates through the walls due to issues like faulty guttering or roofing, cracks in the wall, or poor pointing.

How can I identify the source of penetrating damp in my property?

Identifying the source of penetrating damp involves checking for signs such as damp patches on walls or ceilings, a musty smell, or damaged plaster. The source could be a leaky roof, faulty gutters, cracks in walls, or other structural defects that allow water to penetrate.

Can penetrating damp cause damage to plaster, paint, or wallpaper?

Yes, penetrating damp can cause significant damage to plaster, paint, and wallpaper. It can lead to discolouration, peeling paint or wallpaper, and damage to plasterwork.

Can external factors, such as faulty gutters or roof leaks, contribute to penetrating damp?

Absolutely, external factors like faulty gutters, roof leaks, or even cracks in external walls can contribute significantly to penetrating damp.

What are the effects of penetrating damp on electrical systems within a building?

Penetrating damp can potentially cause severe damage to electrical systems within a building. It can lead to short circuits, malfunctioning appliances, and in extreme cases, electrical fires.

How can I ensure proper ventilation to prevent or minimise penetrating damp?

Ensuring adequate ventilation, especially in areas prone to high moisture levels such as kitchens and bathrooms, can help prevent penetrating damp. This can be achieved by installing extractor fans, regularly opening windows, and using dehumidifiers if necessary.

Is it necessary to conduct regular inspections to detect and address potential penetrating damp issues?

Yes, regular inspections are crucial in detecting and addressing potential penetrating damp issues early. This includes checking for signs of dampness, inspecting the roof and gutters, and ensuring the property’s drainage system is functioning correctly.

How can I maintain proper drainage around my property to prevent penetrating damp?

Maintaining proper drainage involves ensuring gutters and downpipes are clear of debris, fixing any leaks promptly, and making sure the ground slopes away from your property to prevent water from pooling against walls.

Can penetrating damp cause health issues?

Yes, prolonged exposure to penetrating damp can cause health issues, particularly respiratory problems. The damp conditions can promote mould growth, which releases spores into the air that can exacerbate allergies and asthma.

Does penetrating damp cause mould? What is damp mould?

Yes, penetrating damp can lead to the growth of damp mould. Damp mould is a type of fungus that thrives in moist conditions and can appear as a black, green, or white substance on walls, ceilings, or furniture. It can cause a musty smell and lead to a range of health issues.

HOW CAN I GET HELP?

To get help, call London Damp Specialist on 0207 305 5997.

Or, feel free to send an enquiry or book a survey online.

If you submit an enquiry form, one of our damp surveyors will be in touch with you to discuss your problems. We aim to contact you within 24 hours.

  • Damp can cause structural problems such as rot and corrosion that could ultimately cost you money in the long run if not treated properly.

Our Equipment

Damp Meter

Purpose:

Takes comparative surface moisture readings across accessible walls, floors, ceilings and building joinery.

Common Uses / Notes:

Maps surface moisture profiles to help identify rising damp, penetrating damp, condensation, or active plumbing leaks.

Deep-Penetration Damp Meter

Purpose:

Detects moisture changes deep below the immediate surface of structural materials without destruction.

Common Uses / Notes:

Evaluates dampness within wall cores, beneath floorboards, inside subfloors and behind finishes without removing plaster.

Non-Invasive Moisture Scanner

Purpose:

Scans surface planes non-invasively without inserting pins or probes into decorated finishes.

Common Uses / Notes:

Checks decorated walls, tiled surfaces and delicate floor coverings to trace sub-surface water migration non-destructively.

HD Borescope Inspection Camera

Purpose:

Provides high-definition visual examination inside enclosed, narrow, or inaccessible building cavities.

Common Uses / Notes:

Inspects subfloor voids, wall cavities, dry lining and enclosed pipework to locate leaks and defects with minimal disruption.

4K Inspection Drone

Purpose:

Captures high-resolution imagery and video of high-level external structures and rooflines.

Common Uses / Notes:

Inspects roof tiles, chimney stacks, lead flashing, parapet walls, valleys and gutters to locate water ingress sources.

Air Humidity Sensor

Purpose:

Measures ambient air temperature and relative humidity (%RH) levels within living areas.

Common Uses / Notes:

Determines whether atmospheric moisture, cold bridging, or insufficient ventilation supports surface condensation and mould growth.

Thermal Imaging Camera

Purpose:

Visualises surface temperature differentials across walls, ceilings and floors.

Common Uses / Notes:

Detects cold spots, missing insulation, thermal bridges, evaporative cooling zones and concealed water leaks.

Airflow & Ventilation Detector

Purpose:

Measures volumetric air extraction performance (L/s or m3/h) of mechanical extractor fans.

Common Uses / Notes:

Tests kitchen, bathroom and utility fans to verify compliance with UK Building Regulations Part F and control condensation.

Gas Screening Instrument

Purpose:

Screens indoor environments for sewer gas intrusion, combustible gases and combustion concerns.

Common Uses / Notes:

Traces foul odours, soil stack leaks and sewer gases (H2S, NH3, CH4, CO, O2). Does not replace Gas Safe registered safety checks.

Chemical Vapour Detector

Purpose:

Screens air for Volatile Organic Compounds (TVOC/VOC) and chemical substances like formaldehyde (HCHO).

Common Uses / Notes:

Investigates unexplained chemical odours, building material off-gassing, post-flood air safety and indoor air quality.

Airborne Particle Detector

Purpose:

Measures airborne particulate concentrations across precise micron size ranges (PM1.0, PM2.5, PM10).

Common Uses / Notes:

Assesses fine dust, smoke, airborne matter and environmental air quality following water damage or mould outbreaks.

Electrical Socket & RCD Tester

Purpose:

Provides basic safety and protective circuit screening in areas affected by dampness.

Common Uses / Notes:

Identifies socket wiring faults, tests RCD trip functions and checks AC voltage in wet areas. Does not replace an EICR.

Survey Levels & Package Specifications

Level 1

Standard Damp Survey

Standard price: £299 + VAT

Promotional Price: £199 + VAT (Limited Time Offer)

The Level 1 Damp Survey is a basic damp inspection designed to check the main accessible areas of the property for damp, leaks
and visible moisture-related issues.

Equipment Included

  • Damp meter

What Is Included

  • Inspection of walls
  • Inspection of floors
  • Inspection of ceilings
  • Leak inspection of drains and plumbing
  • Damp information and prevention guide

Best For

This survey is best for customers who need a basic damp check where only a damp meter is used. It is most suitable for simple

damp concerns, such as suspected rising damp, visible damp patches, minor moisture concerns or a general check of accessible
areas.

The Level 1 Damp Survey is suitable where the customer wants a straightforward inspection of walls, floors, ceilings, drains and
plumbing without the use of advanced survey equipment.

Level 2

Detailed Damp & Timber Survey

Standard price: £399 + VAT

Promotional Price: £299 + VAT (Limited Time Offer)

The Level 2 Damp Survey includes everything in the Level 1 survey, with additional timber decay inspections and deeper
moisture testing.

Equipment Included

  • Damp meter
  • Deep-penetration damp meter for all building materials
  • Non-invasive moisture detection equipment

What Is Included

  • Inspection of walls
  • Inspection of floors
  • Inspection of ceilings
  • Leak inspection of drains and plumbing
  • Dry rot inspection
  • Wet rot inspection
  • Woodworm inspection
  • Deep moisture detection in building materials
  • Non-invasive moisture testing under floorboards and subfloors where accessible
  • Damp information and prevention guide

Best For

This survey is best for customers who need a damp and timber inspection. It is suitable where there may be concerns about damp,

wood rot, dry rot, wet rot, woodworm or moisture hidden behind building materials.

The Level 2 Damp Survey uses equipment that can read deeper into building materials, including areas such as subfloors, under
floorboards, behind panelling and other accessible hidden areas. This allows us to get a better understanding of whether there may
be hidden damp within the property without dismantling or damaging materials.

This survey is very suitable for home buyers and sellers who want a more detailed damp inspection before purchasing or selling a
property.

Specialised Laboratory Diagnostic Add-Ons

Add-On 1

Laboratory Analysis of Plaster Samples

Price £299 + VAT

Small plaster samples are carefully taken from affected walls and submitted to an independent laboratory for salt analysis. The laboratory tests for the presence and precise concentration of hygroscopic salts, including nitrates and chlorides.

Diagnostic Value: Soluble ground salts are drawn up through masonry during rising damp and remain in plaster permanently. Salt analysis scientifically differentiates true rising damp from condensation or historic leak contamination.

Note: Plaster sampling requires minor material removal and is our only add-on involving minor invasive work.

Add-On 2

Mould Laboratory Testing & qPCR DNA Analysis

Price £299 + VAT

Surface swab or lift samples are submitted to an accredited laboratory for advanced qPCR DNA analysis.

Diagnostic Value: Accurately identifies exact mould species, measures contamination concentrations and detects hidden fungal growth inside cupboards or behind dry lining. Delivers impartial scientific evidence to guide safe environmental remediation.

Add-On 3

Gases, Chemical Vapours & Airborne Particle Testing

Price £299 + VAT

Comprehensive environmental air quality and gas screening tailored to specific property concerns.

Screening Suite Includes: IAQ air quality assessment, Volatile Organic Compounds (TVOC/VOC), Formaldehyde (HCHO), Particulate Matter (PM1.0, PM2.5, PM10), Sewer Gases (H2S, NH3, CH4), Combustion Gases (CO, O2) and ventilation performance.

Diagnostic Value: Air quality issues are often linked to damp, leaks and mould, but they cannot always be identified by a visual inspection alone. This testing helps detect hidden airborne contaminants, gases, chemical vapours and fine particles that may affect the property’s condition and indoor environment. It can also help identify problems such as poor ventilation, sewer gas ingress, off-gassing from building materials, combustion-related gases, or airborne particles following water damage, providing a more comprehensive understanding of the property’s condition.

It is also useful where a property has persistent unpleasant or unexplained odours. The testing can help investigate foul smells caused by damp, water damage, stagnant water, drains, sewer gases or chemical vapours, allowing the source of the odour to be identified more accurately.

Testing includes:

  • Indoor Air Quality Testing- IAQ
  • Volatile Organic Compound Testing- TVOC / VOC
  • Formaldehyde Testing- HCHO
  • Fine Particulate Matter Testing- PM1.0 / PM2.5 / PM10
  • Dust and Smoke Particle Testing- PM1.0 / PM2.5 / PM10
  • Sewer Gas Testing- H2S / NH3 / CH4
  • Gas Leak Screening- CH4 / C3H8
  • Carbon Monoxide Testing- CO
  • Hydrogen Sulfide Testing- H2S
  • Ammonia Odour
  • Testing- NH3
    Oxygen Level Testing- O2
  • Ventilation / Stale Air Assessment- IAQ / TVOC
  • Drain Smell Investigation- H₂S / NH3 / CH4
  • Chemical Odour Investigation- TVOC / VOC / HCHO / NH3
  • Post-Leak Air and Surface
  • Condition Assessment- PM2.5 / TVOC
  • Combustion Gas Safety Screening- CO / O2 / CH4
  • Building Material Off-Gassing Assessment- TVOC / HCHO
  • Airborne Pollutant Screening- PM1.0 / PM2.5 / PM10 / TVOC