Specialist render
Basement Tanking
Cementitious tanking and cavity drain systems for basements, cellars and below-ground rooms.
Below-ground walls face water under pressure, which is a fundamentally different problem from rain hitting a wall. Ordinary render, however strong, will not hold back hydrostatic pressure — water finds the weakest junction and pushes through.
There are two proven approaches. Type A is a barrier system: a multi-coat cementitious tanking slurry bonded directly to the structure, with careful fillet detailing at every wall-to-floor junction, forming a continuous seal. Type C is a drained system: a studded cavity drain membrane that accepts water will get in, channels it to a perimeter drain and sump, and pumps it away. Type A suits sound masonry with modest water pressure; Type C is more tolerant of an imperfect structure and is generally specified where a basement is being converted to habitable space.
When it is the right choice. Choose tanking for cellar and basement conversions, persistently wet below-ground rooms, and any space you intend to make habitable.
Specification at a glance
| Typical guide price | £115–£195 per m² supplied and installed |
|---|---|
| Applied thickness | Multi-coat cementitious system |
| Curing / drying | 7-14 days |
| Guarantee | 20 years |
| Category | Specialist render |
Guide prices are indicative only and exclude scaffold, stripping and repairs. Your written quote follows a free survey.
What is included
- Cementitious tanking slurries
- Cavity drain membrane systems
- Sump and pump installation
- Type A and Type C waterproofing
- Fillets and junction detailing
- Withstands hydrostatic pressure
- Suitable for habitable conversion
- Salt and negative pressure resistant
- Design to BS 8102 principles
- 20-year system warranty
Get a quote for basement tanking
Tell us about the property and we will call you back to arrange a survey.
Related services
What happens next
Four steps from enquiry to finished wall
Free survey
We visit, test the substrate, measure up and identify what caused any existing failure.
Written quote
An itemised fixed price with the system named, materials specified and scaffold included.
Booked in
An agreed start date, scaffold arranged, and a clear run of days set aside for your job.
Finished and guaranteed
Site cleared, scaffold struck, guarantee documents and system warranty issued.
Coverage
Basement Tanking by county
We carry out basement tanking across all 74 counties below. Pick yours to see local detail.
East of England
South East
South West
North West
North East
East Midlands
Yorkshire
London
West Midlands
Wales
Scotland
Northern Ireland
FAQs
Basement Tanking — your questions
What is the difference between Type A and Type C waterproofing?
Type A is a bonded barrier that keeps water out entirely. Type C accepts ingress, then drains and pumps it away behind a membrane. Type C is more forgiving of structural imperfections.
Can any cellar be tanked?
Most can, but the right system depends on water pressure, structural condition and intended use. A survey establishes which approach is appropriate.
Does a tanked basement need a pump?
A Type C cavity drain system does — it relies on a sump and pump. A Type A barrier system does not, though a pump is sometimes added as a backup.
How long does basement tanking last?
A correctly designed and installed system carries a 20-year warranty. Type C systems need periodic pump servicing to maintain that.
What time of year is best for rendering?
Spring through autumn is ideal. Render should not be applied in frost or in very hot direct sun, so winter work needs protection and settled conditions.
Can you render over existing render?
Sometimes, if the existing coat is completely sound and well-bonded. We hammer-test it first. Anything hollow has to come off, because covering failure just hides it.
Are you insured?
Yes — full public liability cover, and we can send the certificate before we start. We are happy to provide RAMS for commercial and contractor work.
Thinking about basement tanking?
Book a free survey and we will confirm whether it is right for your walls before you commit.