01634 47989007460 072891 Mon–Fri 8am–6pm · Sat 8am–3pm HomeAboutServicesDamp & Waterproofing Damp ProofingTanking & Waterproofing Roofing RoofingNew roofsRoof repairsFlat roofsChimney repairsCommercial roofing Exterior & Finishes RenderingExterior paintingFascias & soffitsWood rot repairsNew PVC All services Service AreasMedwayMaidstoneRochesterStroodGillinghamChathamRainhamSittingbourneSheernessAll areas Our WorkReviewsContactRequest Estimate - Home - Services - Tanking & Waterproofing Services # Tanking & Basement Waterproofingin Medway & KentWet Space Made Usable You get a below-ground room that stays dry all year and can hold flooring, plaster and furniture, turning a space you avoid into a room you use, without gambling on a paint-on product. Get my free survey07460 072891 9.97 out of 10 from 12 Checkatrade reviews, free survey and a fixed written price before any work starts. - 12 Checkatrade reviews 9.97 out of 10 average score - Checkatrade & Bark listed Verified customer reviews on both platforms - Free survey, fixed written price The cause diagnosed before the work is priced - Open 6 days a week Mon–Fri 8am–6pm, Sat 8am–3pm - Company no. 15471708 Kent-based, working across Medway from Chatham ## What tanking & waterproofing involves, and when you need it Tanking is structural waterproofing: holding back water that is under pressure from the ground outside rather than simply repelling rain off a wall face. Below ground level there is no damp proof course to reinstate, so the answer is a continuous waterproof system across walls and floor, or a managed drainage system that collects water and takes it away before it reaches your finishes. There are two accepted routes and they suit different buildings. Cementitious tanking bonds a multi-coat waterproof render directly to sound masonry, resisting water pressure at the wall face: strong, thin, and ideal where the structure is solid and space is tight. Cavity drain membrane accepts that water will arrive, holds it behind a studded sheet, and channels it to a perimeter drain and sump, which suits older rubble or uneven walls and gives a more forgiving long-term system. The survey decides which. We look at wall construction and condition, floor build-up, the depth below external ground, existing drainage, evidence of past water levels and where any water can be discharged to. Then you get a written specification and a fixed price covering preparation, the waterproofing system, any sump and pump, and the internal finish. ### Who this is for - Owners of Victorian and Edwardian properties with a damp or unusable cellar - Anyone converting a basement into a utility room, gym, office, store or extra living space - Properties with below-ground rooms that flood or smell musty after heavy rain - Landlords needing a dry, lettable lower-ground floor - Commercial premises with below-ground stock rooms, plant rooms or lift pitsRing the office on 07460 072891 or use the contact page and we will give you a realistic survey date on the call. You can also see everything we do across Medway or read our customer reviews. ### Related services - Damp Proofing - Rendering - Wood rot repairsAll services ### Areas we cover - Medway - Maidstone - Rochester - Strood - Gillingham - Chatham - Rainham - Sittingbourne - Sheerness ## What happens if it is left A wet cellar is not a static problem. Standing moisture and poor airflow strip the space of any storage value, then start on the building above: perished mortar, salt-damaged brickwork, corroding fixings and rot in joist ends and wall plates bearing into damp masonry. That is a structural repair bill arriving through a room you were not using anyway. The health side matters more than people expect. Below-ground rooms with constant moisture and no ventilation grow mould in cavities and behind stored items, and that air does not stay downstairs, it moves up through the building on the stack effect, into the rooms you sleep in. The costly version of this problem is the second attempt. A basement waterproofed with the wrong system, or with a paint-on slurry brushed onto dusty masonry, fails at the weakest point and takes the new plaster, flooring and skirtings with it. Doing it once, on the right system, is almost always cheaper than doing it cheaply twice. ### Common mistakes we are called in to undo - Brushing a waterproof paint or slurry onto unprepared, dusty or friable masonry - Tanking walls and ignoring the floor, so water simply arrives at the junction instead - Fitting a membrane system with no drainage route, sump or discharge point - Blocking the last remaining vents and creating a sealed, mould-growing box - Boarding out and decorating before the waterproofing system is complete and tested ## How the job runs, step by step - Step 1 ### Inspection We assess wall construction and condition, floor build-up, external ground levels, existing drainage, water staining lines and any possible discharge point for a pumped system. - Step 2 ### Diagnosis and system choice We tell you whether cementitious tanking or a cavity drain membrane suits your structure, and why, including the trade-offs in wall thickness, finish and long-term maintenance. - Step 3 ### Preparation Old finishes and failed coatings are hacked off back to sound masonry, joints raked and repointed where needed, fillets formed at wall and floor junctions, and the substrate prepared to take the system. - Step 4 ### System installation Tanking is applied in specified coats to the correct thickness, or the membrane is mechanically fixed and sealed with perimeter channel, sump and pump, then floors and walls are finished ready for decoration. - Step 5 ### Testing, handover and guarantee Pumps and drainage are tested under water, the completed system is walked with you, and you are shown the maintenance points before we clear the site. ## What you get out of it ### Usable floor area A dry basement or cellar becomes a utility, gym, office or store: extra square metres you already own, without an extension. ### Protects the structure above Controlling water below ground protects joist ends, wall plates, mortar and fixings that fail quietly in damp masonry. ### System matched to the building You get the route that suits your walls and drainage, not whichever product is easiest to apply. ### Tested before handover Pumps, channels and discharge are run under water while we are still on site, not left to prove themselves in a storm. ### Better air through the house Removing a permanently damp lower floor improves the air moving up through the rest of the building. ### Finished, not just waterproofed We take the room through to plastered, decoration-ready condition, so there is no second contractor to arrange. ## Tanking & Waterproofing in detail: materials, methods and variations ### Materials and systems Cementitious tanking uses polymer-modified waterproof render and slurry systems applied in multiple coats to a specified total thickness, with reinforcing fillets at wall-to-floor junctions and detailing around any service penetration. Because it bonds to the substrate, preparation is the whole job: everything unsound comes off, joints are raked out and made good, and the surface is keyed and dampened as the manufacturer requires. Cavity drain membrane systems use studded HDPE sheet fixed with sealed plugs, perimeter drainage channel at the wall-floor junction, an inspectable sump chamber and a pump, usually with a battery-backed or dual-pump arrangement where the consequence of failure is high. Walls are finished on battens and board or with a plaster mesh membrane, and floors take a membrane with insulation and screed or a floating floor build-up. Supporting materials matter as much as the headline system: waterstop and hydraulic cement for active water points, sealants and tapes specified by the same manufacturer, and drainage pipework and non-return valves sized for the discharge run. ### Variations and situations Partial tanking suits a cellar where only one buried elevation is affected, often the elevation against a bank or a neighbouring property. Full tanking of walls and floor is the right answer where the whole footprint is below ground and the room is being converted into living space with plaster, flooring and electrics. Retro-fitting to occupied houses usually means working through a single narrow stair with hand-carried materials and no site parking, so we plan waste removal and material delivery around your street rather than assuming a skip on the drive. Where headroom is critical, membrane build-up on the floor is designed to preserve every millimetre we can. Other applications use the same principles: lift pits, plant rooms, inspection chambers, retaining walls in garden rooms, and earth-retaining garage walls where a driveway sits above internal floor level. ### Residential versus commercial Domestic basement work is driven by finish quality and living conditions: flat plastered walls, controlled floor levels, quiet pump selection and tidy sump positioning inside a cupboard or store. Sequencing is planned around the household: one route in, floors protected, and the noisiest breaking-out done in agreed windows. Commercial below-ground work is driven by continuity and access: stock rooms that cannot close, plant that cannot be isolated for long, and pumped systems where a failure floods equipment rather than a floor. We plan phased sections, specify duty and standby pumps where the risk justifies it, and set out the maintenance regime so the system is looked after through its life. ## Recent tanking & waterproofing jobs in Medway & Kent ## Tanking & Waterproofing: your questions answered How much does basement tanking cost?The cost is driven by the area of wall and floor, the condition of the masonry, the system chosen and whether a sump and pump are needed. We survey, specify and give you a single fixed written price. Small partial tanking jobs and full basement conversions sit a long way apart, so a phone estimate would only mislead you. How long does the work take?A single-wall cementitious tanking job is usually a few days. A full cellar with preparation, membrane, sump, drainage and finishes typically runs one to three weeks depending on size and how much breaking-out is involved. The programme is confirmed in writing with the quote. Which is better: tanking or a cavity drain membrane?Neither is universally better. Cementitious tanking is thin, robust and ideal on sound solid masonry. A cavity drain membrane is more forgiving of uneven or rubble walls, is not reliant on a perfect bond, and manages water rather than resisting it. The survey decides, and we explain the reasoning to you. Do I need a pump?Only membrane systems that collect water need one, and only where there is no gravity discharge available. Where we do fit a pump we position the sump for access and specify the arrangement to suit the consequence of failure. Will the room be warm enough to use?Yes, once the water is controlled you can insulate. Floor build-ups take insulation under screed or a floating floor, and wall finishes can be built off insulated board, so the finished room performs like the rest of the house. How long does a waterproofing system last?A correctly specified and installed system is a long-term structural repair. Membrane systems need their pump and drainage inspected periodically, we show you those points at handover, while cementitious tanking is maintenance-free once cured, provided nobody drills through it. Can you help if my cellar has flooded?Yes. Call the office on 07460 072891. We deal with the immediate water and the source first, then survey properly for a permanent system once we can see the structure. Do you cover my area?We work across Medway: Rochester, Chatham, Gillingham, Strood, Rainham, and out to Maidstone, Sittingbourne, Sheerness and the surrounding Kent towns. ## Get tanking & waterproofing priced properly: free survey, fixed written price Tell us what you are seeing and we will book a survey, diagnose the cause and give you one written price. 9.97 out of 10 from 12 Checkatrade reviews across Medway and Kent. Get my free surveyCall 07460 072891 Covering Medway, Maidstone, Rochester, Strood, Gillingham, Chatham, Rainham, Sittingbourne, Sheerness and the surrounding Kent towns. Damp proofing, tanking, rendering and roofing specialists working across Medway and the wider Kent area. Company number 15471708. CheckatradeBark ## Get in touch - 01634 479890 - 07460 072891 - info@intellroofingandbuilding.co.uk - 116 Chatham Grove,Chatham, Kent, ME4 6LZ ## Opening hours - Monday8am – 6pm - Tuesday8am – 6pm - Wednesday8am – 6pm - Thursday8am – 6pm - Friday8am – 6pm - Saturday8am – 3pm - SundayClosed ## Areas covered - Medway - Maidstone - Rochester - Strood - Gillingham - Chatham - Rainham - Sittingbourne - Sheerness © 2026 Intell Roofing & Building Ltd. All rights reserved. AboutPrivacy policyCookie policyTerms & conditionsRequest a free estimate Call nowFree estimate