Below-grade waterproofing specialists · Cobham
Basement Waterproofing in Cobham
Cobham sits along the River Mole, giving much of KT11 a naturally high water table that stays raised well beyond the wetter months. Advanced Damp provides specialist basement waterproofing, basement tanking, cellar tanking, and structural waterproofing solutions for Cobham properties, designed around the town's riverside ground conditions and its mix of period and modern construction.
Over 30+ Years
Below-ground waterproofing across London and the South East.
CSSW Surveyors
Systems designed and specified to BS 8102:2022.
10-Year Guarantee
Written guarantee on all new waterproofing installations.
CHAS Accredited
Fully insured, fixed-price quotations after survey.
Why Cobham Has a Groundwater Problem Unlike Most of Surrey
Most Surrey towns sit away from open water, where ground moisture builds up slowly and predictably. Cobham is different, since the River Mole runs straight through the town and shapes the water table across much of KT11.
The Mole is a slow, meandering river prone to spilling onto low ground after heavy rain, keeping the alluvial soil on both banks consistently damp. Land near the riverbanks, the old mill sites, and the meadows around Cobham's older streets sits on soft, moisture-retentive ground, and much of the town's Georgian and Victorian housing was built directly onto it.
For a Cobham basement, this means water pressure follows the river rather than rainfall alone. Properties nearest the Mole face the heaviest, longest-lasting pressure, while homes set further back still deal with a permanently raised water table. A damp-proofing cream or surface paint won't hold against this; only a properly engineered drainage system can manage it.
Why Cobham Basements Need It
Cobham's position along the River Mole creates groundwater pressure unlike most of inland Surrey. Alluvial soil sits close to the surface, holding water at consistently high levels and pushing it against below-ground walls near the town centre and riverside. Common local risk factors include:
Left untreated, this sustained moisture pressure leads to efflorescence and salt staining, plaster breakdown, mould growth, timber decay in ground-floor joists and, over time, structural deterioration of the masonry itself.
Our Waterproofing Systems
Cobham's riverside alluvium and high water table mean groundwater pressure is active year-round. We specify basement tanking, cellar tanking, cavity drain membrane, and structural waterproofing systems that manage groundwater properly rather than simply resisting it. A waterproofing surveydetermines which solution is right for your property.
Type A · Cementitious Tanking
A rigid bonded coating applied directly to sound masonry. Suited to Cobham cellars with stable brickwork and lower moisture risk storage spaces, plant rooms and vaults where full habitable conversion is not required.
Basement tanking →Type C · Cavity Drain Membrane
Our most specified system for KT11. A studded membrane channels groundwater safely to a sump rather than resisting it. The reliable choice where sustained hydrostatic pressure makes blocking water impractical.
Cavity drain membrane →For riverside apartment conversions or new basement additions on large Putney family homes, see our structural waterproofing and cellar tanking services. structural waterproofing and cellar tanking system designed to BS 8102:2022.
How We Work
River Mole Groundwater & Assessment
A CSSW surveyor assesses how close your Cobham property sits to the Mole's alluvial zone, identifies the water source and pressure level, and checks for any previous failed treatments before recommending a system.
System Design & Fixed Price
We specify the right system for KT11's riverside groundwater conditions to BS 8102:2022 and provide a fixed price in writing before any work begins.
Installation & Guarantee
Our own teams carry out every installation in Cobham with no subcontracting. A written 10-year guarantee is issued on completion. For riverside properties with higher pump demand, we advise on annual sump servicing intervals
Why Choose Advanced Damp in Cobham?
What Our Customers Say
"The reviews for this company looked good, so I called to make enquiries. The representative I spoke with (Lydia) was extremely pleasant and helpful, explaining the company's terms very clearly and professionally. I received a visit from Lionel Sewell, who carried out a thorough examination of the area concerned and talked me through the probable causes and courses of action, showing me thermal imaging and photos to explain the details. He was very pleasant, I was absolutely pleased with the results, which were sent to me in detail (with copies of photos and imaging, etc) within 24 hours. £250 well spent (this sum is deductible if they do the remedial work)."
Colin; Trustpilot"This is my 4th time hiring Advanced Damp. As a property investor, I can’t stress how important it is to find contractors you trust. I’ve had surveys done on all 4 properties and went ahead with work on the 3rd last week (one of the properties, the survey report came back fine). Their team is always communicative, on time, gets the work done quickly, and cleans up after themselves. Currently standing in the room where there was penetrating damp from the gutters we had fixed - it’s spotless, and the work has clearly been done well."
Baylee Greenberg, Google ReviewsCobham Basement Waterproofing FAQs
Does my Cobham basement need waterproofing, or is damp proofing enough?
Standard damp proofing is engineered for above-ground walls — not for the alluvial groundwater pressure that the River Mole creates beneath KT11. If your basement shows any moisture, a specialist waterproofing system is the correct response.
Which waterproofing system is right for my Cobham property?
Properties closest to the Mole face the highest sustained pressure and almost always need a Type C cavity drain membrane with sump and pump. Properties set further back may suit Type A basement tanking where masonry is sound and pressure is lower. A waterproofing survey establishes which applies.
Can you waterproof a Cobham basement for a living space?
Yes. Habitable conversions near the Mole need a Type C cavity drain system with a sump pump to BS 8102:2022. For flood-adjacent properties, we recommend twin-pump installations with high-water alarms to maintain performance when river levels rise.
How much does basement waterproofing cost in Cobham?
Most KT11 projects fall between £6,500 and £12,000 + VAT. Riverside properties requiring twin-pump setups or remedial stripping of failed systems sit towards the higher end. Fixed price confirmed after survey.
Is the work guaranteed?
Yes, every installation carries a written 10-year guarantee. Given the River Mole's influence on KT11's water table, we particularly recommend annual sump servicing to keep systems performing after wet winters.
Do I need a waterproofing survey before getting a quote?
Yes, and the distance from the Mole matters as much as the building itself. Two properties on the same street can face very different pressure levels depending on their proximity to the riverbank. A waterproofing survey identifies that before anything is priced.
Related Services
A Real London Type C Project
Commercial Waterproofing Installation
Learn how our experienced team completed a commercial basement waterproofing project using a cavity drain membrane system that meets modern waterproofing standards and delivers reliable long-term performance.
Professional Basement Waterproofing for Cobham Properties
From initial surveys to complete waterproofing installations, we support homeowners and businesses across Cobham with solutions tailored to their property's unique requirements.
Book a Cobham Basement Waterproofing Survey
If your Cobham property has a cellar, basement, or lower-ground floor showing signs of moisture, the first step is a survey by a CSSW-qualified specialist who understands KT11's riverside groundwater conditions.
We will assess your specific building, identify the source and type of water ingress, and specify the right system in writing with a fixed price. The survey fee is credited against the cost of work if you proceed with us.