Solving Basement Moisture Problems: A Comprehensive Guide to Tanking

It’s no secret that basements, with their deep-set locations and closeness to the ground, are prone to moisture problems. If you’re frustrated with that perpetual damp feeling or are worried about the potential for mould growth in your basement, this guide is for you. We’ll explore the reliable method of tanking – an effective way to keep your basement dry and comfortable.

Why is My Basement Damp?

Understanding the root cause of the problem is always a good place to start. Basements are typically below ground level, making them susceptible to water ingress. Water pressure from the soil surrounding your basement can force moisture through walls and floors. What’s more, limited ventilation and natural light make basements an ideal spot for humidity to settle.

What is Tanking?

Simply put, tanking is a waterproofing method used to treat and protect basements from moisture. Think of it as creating a barrier or a ‘tank’ around your basement walls and floor. This barrier repels external moisture and prevents it from entering the internal space.

  • Liquid applied membranes: This is a liquid solution that, when applied to the surface, dries to form a waterproof barrier. It’s a bit like painting your basement with a protective coat, ensuring that water stays out.
  • Cementitious tanking: This involves applying a thick slurry to the walls and floor. Once it sets, you’ve got a solid, water-resistant layer that guards against dampness.
  • Cavity drain membranes: A slightly different approach, cavity drain membranes create a gap between your basement wall and the protective layer. Any water that does penetrate will flow down this gap to a drain.

Tanking Steps: From Start to Finish

Taking the time to properly tank your basement is a thorough process. It’s crucial to follow each step diligently to ensure a successful and long-lasting result. Here’s an in-depth look at the steps involved in tanking your basement.

1. Preparing the Area

Remove all furniture, storage boxes, and other items from the basement. This will give you ample room to work and inspect the area.

Before any waterproofing can occur, surfaces must be spotless. Dust, dirt, or loose debris can compromise the adhesion of the tanking materials. Using a stiff brush, clean the walls and floors, and consider using a mild detergent if there’s stubborn grime.

If your basement is wet or has visible damp patches, use fans or dehumidifiers to dry the area thoroughly.

2. Inspect and Repair

In Marylebone, most bars and restaurants have a basement for packing or any other purpose. With the type of weather that Marylebone has, it is very easy for dampness to occur on the walls of the basement. While damp in small amounts is not as dangerous, when it accumulates it can it up an entire wall thereby causing the destruction of the structure. Some of the advantages of basement damp proofing thereby include:

3. Choose Your Method

The severity of moisture problems will help determine the right tanking method. If your basement only experiences mild dampness, a liquid-applied membrane might suffice. On the other hand, for basements with significant water ingress, a more robust solution like cementitious tanking or cavity drain membranes might be necessary.

Plus, consider your future plans. If you want to transform your basement into a living space, certain tanking methods might be more suitable due to their finish or durability.

4. Application

Whether you’re doing it yourself or with the help of a professional, it’s important to stick to the manufacturer’s guidelines. This ensures that the product performs as intended.

When applying the tanking product, make sure you cover every nook and cranny. It’s always better to err on the side of caution and apply a little more than to miss a spot.

Depending on the product and the severity of the moisture issue, multiple layers might be necessary. Let each layer dry completely before applying the next.

5. Monitor and Maintenance

Once the tanking process is complete and everything has dried, inspect the area again. Check for any missed spots or areas that might need a touch-up.

Every few months, especially during wet weather, inspect your basement for any signs of moisture. Early detection of issues will allow for timely repairs.

If you’ve chosen to use cavity drain membranes, ensure that the drainage system remains unclogged. Regularly clear out any debris to ensure efficient water flow.

Advantages of Tanking Your Basement

Taking the steps to tank your basement isn’t just about saying goodbye to that clammy, uncomfortable feeling. The process brings a variety of benefits, both immediate and long-term, that can enhance the quality of your life and the value of your property.

A Healthier Home Environment

Damp environments are a breeding ground for mould and mildew. These fungi can produce allergens, irritants, and even toxic substances. By tanking your basement, you’re not only preventing the unpleasant sight and smell of mould, but you’re also ensuring a healthier environment for your family. Respiratory problems, skin irritations, and allergies can all be triggered or exacerbated by mould exposure.

Utility Savings

Damp basements can make the entire house feel colder, leading to increased heating costs in the winter. By sealing off this moisture, your home can become more thermally efficient, thus possibly leading to reduced energy bills.

Protection for Your Possessions

If you are using your basement for storage, moisture can be a real enemy. From books to electronics to cherished family heirlooms, many items can be damaged or even entirely ruined by persistent dampness. Tanking ensures your possessions remain in pristine condition.

Versatility of Space

A dry, well-maintained basement offers endless possibilities. Whether you’ve always wanted a home gym, a library, a wine cellar, or even a small studio for arts and crafts, tanking provides the canvas for these dreams to become a reality.

Added Structural Integrity

Constant moisture exposure can weaken the very foundation of your home. Over time, this can lead to structural issues that can be costly to repair. By tanking your basement, you’re not just protecting the space but also maintaining the structural integrity of your home.

Boosted Property Value

Home buyers today are well-informed and cautious. A dry, useable basement is a significant selling point. Not only does it increase the effective square footage of the living space, but it also signifies a well-maintained property. Homes with tanked basements can command higher prices on the property market.

Is your basement in need of damp proofing? Contact London Damp Specialists today for all your basement tanking needs.

Professional Damp Diagnostic Equipment

Electronic Moisture Meter

Purpose:

Takes comparative moisture readings from accessible walls, floors, ceilings and other surfaces to identify abnormal moisture patterns.

Common Uses / Notes:

Helps the surveyor map affected areas and identify patterns associated with rising damp, penetrating moisture, condensation and potential leaks. Readings support the survey but are not a diagnosis on their own.

Deep-Reading Moisture Meter

Purpose:

Investigates below the immediate surface of building materials without requiring extensive removal of finishes.

Common Uses / Notes:

Helps locate moisture within walls, beneath accessible floors, inside subfloor areas and deeper within the building fabric where hidden moisture is suspected.

Non-Destructive Moisture Scanner

Purpose:

Checks for changes in moisture beneath walls, ceilings and flooring non-invasively without puncturing or damaging the finished surface.

Common Uses / Notes:

Ideal for decorated walls, ceilings and flooring where pin testing would be undesirable. Useful for tracing water migration paths and comparing dry areas against suspected damp sections.

High-Definition Borescope Camera

Purpose:

Provides a close visual inspection of concealed or difficult-to-access spaces without opening up large sections of the building.

Common Uses / Notes:

Used beneath floors, inside wall cavities, behind linings and around hidden pipework to uncover leaks, hidden moisture, timber decay, or construction defects with minimal disturbance.

4K Aerial Drone

Purpose:

Captures high-resolution images of roofs, chimney stacks and other inaccessible high-level external areas.

Common Uses / Notes:

Inspects roof coverings, chimney stacks, flashing, guttering, parapet walls, valleys, high-level brickwork and difficult elevations to reveal defects linked to penetrating damp and water ingress. Subject to weather, safety rules and flight regulations.

Indoor Humidity Monitor

Purpose:

Measures the amount of moisture held within the indoor air (relative humidity and temperature).

Common Uses / Notes:

Helps determine whether high ambient humidity, insufficient ventilation, or surface condensation could be contributing to black mould growth and damp conditions.

Infrared Thermal Imaging Camera

Purpose:

Displays surface temperature variations across walls, floors and ceilings.

Common Uses / Notes:

Assists in identifying cold bridging, condensation risk, insulation irregularities, thermal patterns and hidden water leaks. Interpreted alongside physical moisture readings rather than treated as proof of damp on its own.

Ventilation and Airflow Tester

Purpose:

Tests the extraction performance and airflow velocity of mechanical extractor fans and ventilation outlets.

Common Uses / Notes:

Assesses extractor fans in kitchens, bathrooms and utility rooms to determine whether moisture-producing areas have sufficient extraction rate (L/s or m3/h) to control humidity, condensation and mould risk.

Multi-Gas Detection Equipment

Purpose:

Screens indoor air to identify certain gases present within the property.

Common Uses / Notes:

Supports investigations involving drain smells, suspected sewer gases (H2S, NH3, CH4), combustion concerns (CO, O2) and flammable gases (CH4, C3H8). Does not replace testing or certification by a Gas Safe registered engineer.

VOC and Chemical Vapour Monitor

Purpose:

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

Common Uses / Notes:

Useful when investigating unusual chemical smells, building material emissions/off-gassing, conditions following water damage, or general indoor air quality concerns.

Fine Particle Monitor

Purpose:

Measures airborne material and particle concentrations across precise size ranges, including PM1.0, PM2.5 and PM10.

Common Uses / Notes:

Supports investigations involving fine dust, smoke, poor indoor air conditions and environments affected by post-leak damage or extensive mould contamination.

Socket and RCD Testing Device

Purpose:

Provides limited, basic electrical safety and protective circuit screening during the inspection.

Common Uses / Notes:

Helps identify certain socket wiring problems, confirms the operation of Residual Current Device (RCD) protection and detects AC voltage in damp areas. Does not constitute a full electrical inspection or an Electrical Installation Condition Report (EICR).

Equipment & Inspection Levels

Level 1

Essential Damp Survey

Standard price: £299 + VAT

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

Offer ends in--Days--Hours--Mins--Secs

Repair Deduction: Full survey cost deducted if remedial work is instructed.

The Level 1 survey is an entry-level inspection of the main accessible areas. It is intended for relatively straightforward concerns involving visible damp, suspected rising damp or isolated moisture patches.

Equipment Provided

  • Electronic damp meter

Areas and Checks Included

  • Accessible walls
  • Accessible floors
  • Ceilings
  • Visible drain and plumbing leak checks
  • Damp information and prevention guidance

Recommended For

This option is suitable when a customer needs a basic assessment using a standard damp meter. It can be used for a general check or where there is a simple and clearly defined moisture concern.
The inspection covers accessible internal surfaces, drains and plumbing but does not include the advanced diagnostic instruments provided with the higher survey levels.

The survey price will be deducted if we undertake the recommended remedial work.

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Level 2

Enhanced Damp & Timber Survey

Standard price: £399 + VAT

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

Offer ends in--Days--Hours--Mins--Secs

Repair Deduction: Full survey cost deducted if remedial work is instructed.

The Level 2 survey includes the Level 1 inspection together with deeper moisture investigation and checks for timber-related deterioration.

Equipment Provided

  • Electronic damp meter
  • Deep-reading moisture meter
  • Non-invasive moisture scanner

Areas and Checks Included

  • Accessible walls, floors and ceilings
  • Visible drain and plumbing leak checks
  • Wet rot inspection
  • Dry rot inspection
  • Woodworm inspection
  • Deeper moisture readings from suitable building materials
  • Non-destructive moisture checks beneath accessible floors and within subfloor areas
  • Damp information and prevention guidance

Recommended For

It is appropriate for concerns involving wet rot, dry rot, woodworm, concealed dampness or moisture below finished surfaces.
The combination of deep-reading and non-invasive instruments allows the surveyor to gather information from subfloors, beneath accessible floorboards, behind suitable panelling and within other reachable concealed areas without unnecessary dismantling.

The Level 2 survey is a good choice for buyers and sellers who require a more detailed damp and timber assessment before proceeding with a property transaction.

The survey charge will be deducted from the cost of remedial work undertaken by us.

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Specialised Laboratory Testing Add-Ons

Add-On 1

Laboratory Analysis of Plaster Samples

Price £299 + VAT

(The cost of this add-on is deducted from your repair bill if we carry out the recommended remedial works).

Small plaster samples are carefully taken from affected walls and sent to an independent laboratory to analyse the concentration of hygroscopic salts (chlorides and nitrates).

Why it matters: Hygroscopic salts are carried by ground moisture during rising damp and remain in plaster even after masonry dries.

Diagnostic value: Differentiates true rising damp from condensation, rainwater penetration, or temporary plumbing leaks.

Note: Salt analysis can be particularly helpful when moisture-meter readings alone do not provide a sufficiently clear diagnosis. It may assist in distinguishing possible rising damp from condensation, water penetration or residual contamination caused by a historic leak. 

The results are considered together with the moisture profile, construction of the building, external ground levels, condition of the damp-proof course and other survey observations. This is the only additional service requiring minor invasive work because physical plaster samples must be collected. If we undertake the recommended remedial work, the survey cost will be deducted from the cost of that work.

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Add-On 2

Laboratory Mould & qPCR DNA Analysis

(The cost of this add-on is deducted from your repair bill if we carry out the recommended remedial works).

Surface swab or lift samples are submitted to an accredited laboratory for advanced qPCR DNA testing to identify exact mould species and spore concentrations.

Why it matters: Identifies toxigenic species (e.g., Stachybotrys chartarum) and concealed mould growth behind dry lining or furniture.

Diagnostic value: Establishes whether mould contamination is localised or widespread, enabling precise environmental remediation planning.

This service may be beneficial where:

  • A persistent musty smell is present
  • Mould repeatedly returns after cleaning
  • The property has experienced previous water damage
  • Contamination is suspected behind furniture or inside cupboards
  • Occupants have concerns about the indoor environment
  • The extent of visible mould is unclear
  • Independent laboratory evidence is required

Note: The results can help establish whether contamination appears isolated or more widespread. They may also assist with planning appropriate cleaning, removal, drying, ventilation or moisture-control measures.

Laboratory mould testing does not replace the need to investigate the moisture source. Mould is normally a symptom of excess moisture, condensation, leakage or inadequate ventilation, so the underlying cause must also be identified. If we carry out the recommended work, the survey fee will be deducted from the cost of that work.

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Add-On 3

Gas, Vapour & Airborne Contaminant Screening

Price £299 + VAT

(The cost of this add-on is deducted from your repair bill if we carry out the recommended remedial works).
Comprehensive environmental air quality screening for properties with persistent odours, post-flood contamination, or air quality issues.

Screening includes:

  • Indoor air-quality assessment – IAQ
  • Volatile organic compounds – TVOC/VOC
  • Formaldehyde – HCHO
  • Fine airborne particles – PM1.0, PM2.5 and PM10
  • Dust and smoke particles – PM1.0, PM2.5 and PM10
  • Sewer gas screening – H2S, NH3 and CH4
  • Flammable gas screening – CH4 and C3H8
  • Carbon monoxide – CO
  • Hydrogen sulphide – H2S
  • Ammonia – NH3
  • Oxygen levels – O2
  • Stale-air and ventilation assessment – IAQ and TVOC
  • Drain odour investigation – H2S, NH3 and CH4
  • Chemical smell investigation – TVOC, VOC, HCHO and NH3
  • Post-leak air and surface-condition checks – PM2.5 and TVOC
  • Combustion gas screening – CO, O2 and CH4
  • Building-product off-gassing assessment – TVOC and HCHO
  • General pollutant screening – PM1.0, PM2.5, PM10 and TVOC

Diagnostic value: Pinpoints the source of foul drain odours, chemical off-gassing and stale air problems linked to poor ventilation. It is also useful when a property contains a persistent foul, stale or unexplained smell. Odours can originate from damp building materials, stagnant water, contaminated drains, sewer gases, mould-related conditions or chemical vapours. Targeted screening helps narrow down the possible source and supports further investigation.

Note: Screening results do not replace specialist gas, environmental or medical assessments where these are required. The survey charge will be deducted if London Damp Specialists completes the recommended remedial work.

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