Suitable Basement Conversion


Once you have converted the loft, and perhaps added an extension, the only place to go is down. If you feel your next home is financially just too far out of reach or you love the home you live in but are running out of space, here are some things you need to consider before planning your basement conversion.

Is it feasible?

According to the experts, only modern terraced properties built on a raft foundation are not suitable for a basement conversion or construction; otherwise, whether you have a shallow basement or no basement, you can extend your property downwards.

Before you start any work, check with the local planning department whether you need planning permission. You could also commission a site survey to assess any issues with drains, ground condition and the local water table. If you are a leaseholder, you will need the freeholder’s permission before any work can be carried out.

How do I find an expert?

This is not a job for a keen DIYer or even your friendly local builder. You must use a specialist London basement company to carry out the work, including tanking and waterproofing. The company you use must therefore be an expert in waterproofing works in addition to structural engineering.

Look for a London basement company that is well established and is willing to show you examples of past work and put you in touch with its clients. Take a look at the company website, which should give a comprehensive overview of the services it offers, and ask friends, family or colleagues who may have undertaken a basement conversion for recommendations.

How much will it cost?

A good specialist basement company will give you a clear and detailed breakdown of the costs involved, depending on whether you want a conversion of an existing basement space or the construction of a whole new basement extension, often extending under the garden or drive.

It is cheaper to ask for a quote for just the watertight shell and core works; however, a more comprehensive quote for fitting out may be more realistic. The brand value and reputation of your contractor, and their spare capacity and overheads, may also affect the quote.

If your quote seems on the high side, ask the company what guarantees and insurances are included, and whether it is factoring in the risk associated with the geology of your plot and the access routes. Getting a proper site survey done will cost, but may also bring down your quotes.

Can I stay at home?

One of the advantages of a basement conversion is that you can stay at home during the process. Although you may prefer not to project manage, you can be on hand to make practical decisions that ensure the build goes smoothly.