Expect to pay about £100 – £120 per m² for all the walls and flooring that need to be waterproofed. This can vary widely, from £40 per m² up to £250 per m² depending on the contractor and various factors such as finishes, existing condition and whether the room needs to be habitable.
Cost per m²
Basement waterproofing is tough to cost, simply because there are so many factors involved.
A good rule of thumb is between £100 – £120/m² for all the areas of walls, floors and ceilings that need to be waterproofed.
For example, for a basement of 4m width, 5m length with walls of 3m high:
- The floor would cover 20m² (4m x 5m)
- The walls would cover 54m² (2 x [4m x 3m] + 2 x [5m x 3m])
- The ceiling doesn’t need waterproofing
- Therefore, a total of 74m² of waterproofing is needed.
However, this varies considerably depending on the contractor and other factors. We saw quotes as low as £40/m² as may charge up to £250/m² depending on factors such as the level of finishing required.
Total Cost
Some example dimensions of basements and rough cost approximations are given below:
| Basement Dimensions | Avg. Range | Min – Max |
|---|---|---|
| 4m x 5m, with 3m high walls (floor and walls) | £7,700 – £9,100 | £3,200 – £19,400 |
| 5m x 6m, with 3m high walls (floor and walls) | £10,000 – £12,000 | £4,100 – £25,000 |
| 6m x 7m, with 3m high walls (floor, walls and ceilings) | £16,800 – £20,000 | £6,800 – £42,000 |
As mentioned above, prices can vary considerably due to many important factors.
Therefore, most companies will offer to conduct a survey free of charge. However, if they do charge, expect the fee to be in the region of £100 – £200.
Factors Affecting the Cost
These are the main factors contractors will consider when pricing up the works:
Will the Room Need to Be Habitable?
If you’re planning to use your basement as a habitable room, this will cost more as it will need to comply with extra Building Regulations. This will affect the type of method a contractor uses.
For functioning rooms, a contractor could waterproof a basement using a cavity drain membrane system including a sump and pump. If you just need to make the room dry, a contractor could waterproof the basement using a cementitious tanking system. This process would cost less.
Are Extra Finishing Works Needed?
There may be then extra associated building works required after the waterproofing. These include works such as levelling, plastering to walls, floor screed, skirting boards or electrics to make a room habitable. Expect to pay a few thousand pounds extra if these works are required.
What are the Basement Dimensions?
Larger dimensions will cost more, but the cost per m² will reduce.
What is the Existing Wall and Floor Construction Like?
The existing wall and floor construction, plus the condition of the substrate, will determine which waterproofing products/systems are suitable for the basement.
Is it a Full Basement or Partially Underground?
If it is open to one side, then there is less digging down required. This reduces costs.
Are the Ceilings Vaulted or Arched?
Vaulted, pitched or arched ceilings cost more to waterproof than flat ceilings as they are more complex to lay.
Where is the Basement Located?
Certain areas of the UK are more expensive. Areas in the south tend to have higher living costs and overheads compared to the north.
Particularly in London, expect to pay 10-20% in addition to the average. If a contractor needs to travel outside of their standard designated areas, expect to pay extra.
If the work is undertaken in busier areas, parking is usually more expensive. Parking prices in London are very high and contractors factor these into their quotes.
Why Can You Trust This Data
We contacted 26 different basement waterproofing contractors. Many didn’t want to give a figure without a site survey done first.
However, when given specific measurements, some were able to give ballpark figures depending on certain factors being met. Upon further questioning, some were able to give approximate m² costs.
We then derived total costs from the m2 we produced and matched it against the existing total ballpark costs we received. These costs were researched independently.
If you see similar costs and measurements and factors used on other sites (particularly if similar sized rooms are used), it is likely to have originated from this research.
We would like to thank the following companies for their insights:
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