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Last updated: 8 June 2023
Basement waterproofing costs
Waterproofing your basement not only helps protect your foundations from potential water and flooding damage, but it also gives you additional space to use in your home. No more damp smell or risk of water damage to furniture or belongings.
One of the most common causes of water damage to basements is water leaking through the joint where the floors and walls meet. Often rainwater or melted snow can seep into small cracks and cause the most damage to the basement walls.
We’ve put together this guide to show you the average basement waterproofing costs in the UK. For the breakdown of costs, we spoke to the online estimators at B3 Cost Consulting – a team of professional Estimators and Quantity Surveyors.
| Basement type (floor, walls & ceiling) | Range - Low | Range - High | Average cost |
|---|---|---|---|
| Average basement waterproofing (per m2) | £40 | £250 | £120 |
| 4m x 5m, with 3m high walls | £2,960 | £18,500 | £8,000 |
| 5m x 6m, with 3m high walls | £3,840 | £24,000 | £10,500 |
| 6m x 7m, with 3m high walls | £6,480 | £40,500 | £17,500 |
| Last updated: May 2024 Our costs are ballpark averages - get a local tradesperson to quote now | |||
How much does it cost to waterproof a basement?
No two basement waterproofing projects are the same, but to help you calculate the total cost of waterproofing your basement, a good guide price to work with is about £120 per m2.
For accurate quotes for either waterproof sealer treatment and/or basement waterproofing membrane costs, we recommend speaking to your local waterproofing specialists. They'll be able to provide you with specific prices for your basement waterproofing project.
Basement waterproofing costs estimate
One of the biggest factors that will affect the total price you pay for waterproofing your basement is the size of the space. The larger the basement, the more it will cost to waterproof.
For a four-metre x five-metre basement with three-metre high walls, the average waterproofing cost is about £8,000. If you have a five-metre x six-metre basement, the cost is around £10,500. And for a larger basement measuring six-metres x seven-metres with three-metre high walls, the average cost of waterproofing is in the region of £17,500.
Most basement waterproofing specialists will offer to carry out a survey of the basement first, free of charge. However, some may add a fee for the survey, which will be around £100 to £200.
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Factors affecting the cost of waterproofing a basement
When calculating the budget for waterproofing your basement, it’s important to consider a number of factors that will affect the overall cost. These include:
Size of basement
Any prep or structural work needed
If the basement needs to be habitable
The shape of the basement (awkward room structures will increase the cost)
Quality of materials used
Cost of basement waterproofing membrane, if used
Additional tasks (such as levelling, floor screed, skirting boards or electrics)
Time taken to complete the job
Where you live
Additional costs for waterproofing a basement
There are a few additional costs that you might need to consider for waterproofing your basement. Hiring a dehumidifier to dry out the basement costs £65 to £85 per week. If you’re buying any of the materials yourself, proprietary filler costs £65 to £75 per 25kg. And the price of waterproof sealer can range from £25 to £85 per five litres.
Useful basement waterproofing checklist
Only waterproof in dry conditions, not in standing water or damp walls.
Do not apply waterproofing sealer over painted walls or efflorescence.
External waterproofing is more effective but costlier.
Fill any cracks with a proprietary filler prior to waterproofing.
Ensure the waterproofing sealer is a masonry waterproofing product.
Speak to your local waterproofing specialists for their professional advice and quotes of accurate costs for the work.
Shop around for fair and competitive basement waterproofing costs.
Always hire a tradesperson with experience and check reviews from their previous customers to ensure they do good work.
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