Guide
Basement tanking cost per m²: what UK firms publish, by system
Updated
Basement tanking cost is quoted per square metre of wall and floor treated, and the system decides the rate. The firms that publish a rate put Type A cementitious tanking at £40 to £100 per m² and a Type C cavity drain membrane at £70 to £150 per m².
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Per square metre, by system
| System | Rate per m² | Firm | Source |
|---|---|---|---|
| Type A cementitious tanking | £40 to £80 | North London Damp | North London Damp: Basement Waterproofing Cost Estimator |
| Type A cementitious tanking, supply and apply | £50 to £100 | MPS Concrete | MPS Concrete: Basement Tanking Cost UK |
| Type C cavity drain membrane | £70 to £140, plus a £1,500 to £3,500 sump pump system | North London Damp | North London Damp: Basement Waterproofing Cost Estimator |
| Type C cavity drain membrane, including sump and pump | £80 to £150 | MPS Concrete | MPS Concrete: Basement Tanking Cost UK |
| Type C cavity drain membrane | £80 to £120 (London £100 to £150) | Advanced Damp | Advanced Damp: Basement Waterproofing Cost Guide |
| External tanking or membrane, excavation extra | £90 to £180 | MPS Concrete | MPS Concrete: Basement Tanking Cost UK |
The three firms agree on the order: a cementitious slurry on sound walls is the cheapest per square metre, a cavity drain membrane that carries water to a sump and pump costs more, and anything applied to the outside face costs most because the ground has to be dug away first.
Source: MPS Concrete: Basement Tanking Cost UK
What a whole cellar or basement comes to
MPS Concrete puts a small single room cellar with cementitious tanking at £3,000 to £8,000, and a domestic basement with a cavity drain membrane, sump and pump for living space at £8,000 to £18,000, both excluding VAT.
Source: MPS Concrete: Basement Tanking Cost UK
North London Damp prices cellar projects at £1,000 to £3,000 for dry storage and £8,000 to £30,000 or more for habitable space; Advanced Damp gives £8,000 to £14,000 for a cavity drain system in a Victorian brick cellar in London.
Source: North London Damp: Basement Waterproofing Cost Estimator
What moves the price
- The water: a basement that sits in groundwater year round needs a drained system and a pump, which is the dearer route.
- The use: storage needs a lower grade of dryness than a bedroom or kitchen, and the grade decides the system.
- The walls: cracks, failing joints and old plaster have to be dealt with before a slurry will bond.
- Access: narrow stairs, low headroom and no route for materials slow the work and raise the labour per square metre.
Those four are the drivers MPS Concrete lists on its own price page; every firm we read prices the job after a survey for the same reasons.
Source: MPS Concrete: Basement Tanking Cost UK
The survey comes first
North London Damp advises starting any real project with a BS 8102 design survey at £250 to £450; Advanced Damp quotes a design survey at £400 to £800 in London, and MPS Concrete lists a waterproofing design specialist at £750 to £3,000.