Basement / Cellar Conversions in London Greater London (98)

If you've got the budget to take on the job, a cellar conversion is a no-brainer. Benefits include:

• Extra living space – Perfect for a growing family or creating a quiet retreat
• Independent living area – Ideal for an older relative or guest annexe
• No need to move – Gain valuable space without the cost or stress of moving
• No loss of garden space – Unlike extensions, basements make use of existing footprint
• Added property value – A well-finished cellar can boost your home’s market appeal

A cellar basement conversion is one of the biggest building projects homeowners can take on. So it's important to understand what's involved.

Here's the main steps that a basement cellar conversion company will take to transform your space:

• Excavate your basement or lower the basement floor level to gain extra head height (if necessary)

• Install any additional support if needed

• Add a waterproof membrane to the space

• Fit utilities

• Install flooring and plaster the walls

• Add heating and lighting

• Decorate and furnish the space

You can find more information and advice in our how to convert a cellar and cost of finishing a basement guides.

The amount you pay for your cellar conversion will vary depending on a number of factors, including:

• Size of basement

  • The larger your basement is, the more you’ll pay for it to be converted

• Conversion or excavation

  • It’s more expensive to build a new cellar than convert an existing cellar

• Structural support

  • If your home needs additional structural support in order to secure your basement, this will be an extra cost

• Cellar purpose

  • Depending on how you plan to use your new basement, the conversion price may vary. For example, a wine cellar requires much less work than a home gym

• Utilities

  • If you plan to add power, gas, plumbing and air conditioning to your basement, this will increase the conversion price

Most conversions take 8–16 weeks, depending on size, depth, and whether structural work or excavation is required.

That said, you're best off speaking to a basement conversion company directly to get a clearer idea on timescales for your home.

Search your postcode in our free directory or request a quote to find basement conversion specialists covering London.

To help you find basement and cellar conversion companies in London, consider these tips:

• Check online reviews to determine their reputation and quality of work
• Ask about their experience
• Verify their public liability insurance, so you know they’re covered against any potential accidents or damages
• Get multiple quotes from at least three tradespeople so you can compare prices and services
• Use Checkatrade and hire one of our approved members that have undergone up to 12 checks so that you can hire with confidence