By digging down into the cellar or basement, you can create an additional floor running the entire length of your house, and that opens up a wealth of opportunities for a bigger and better home.

Why do a Basement Conversion?

In the northern United States and Canada, many homes are built with basements that are used as utility rooms, playrooms, family rooms and even to house pools. Here in the UK, with space at such a premium, we’re waking up to the fact that the area under our homes may have great potential, and an increasing number of us are transforming previously wasted space into lifestyle-enhancing home cinemas, gyms and spas, as well as rooms with more traditional functions. And forget damp, dark and dingy – modern construction methods mean that today’s basements are warm, light, comfortable and airy.


What Type of Home is Suitable?

A basement conversion is particularly suitable for a terraced or semi-detached urban home where adding a conventional extension or going up into the loft isn’t possible. Perhaps the property has already been extended and there’s nowhere else to go, the garden is too small, or you’re after a pool, gym or new kitchen, which wouldn’t be practical in a loft. And, although more costly than other improvements, it could boost the value of your home considerably.

Making a Plan

As with any home build, you will need to create a floor plan before you start doing anything. Be sure to include where the exisiting walls and stairs are as well as any walls or doorways you want to add to the space. If you plan to divide the existing space into smaller rooms, then don’t forget to include a hallway. Most hallways are at least three feet across.

However, the visible basement is not the only thing you should consider. For those who live in chilly climates, make sure you make plans to properly insulate your exterior walls if they are not already insulated. Other items that go in your walls and require a plan include plumbing, electrical wiring and heating and cooling systems.



Depending on how you have designed your basement conversion, you may or may not need to install plumbing. If there are no plans for a bathroom, washroom or laundry room, then it is unlikely that you will need to install plumbing in your basement.

However, if plumbing is necessary, then you’ll need to decide just where the pipes will go. Although it might be the most convenient to place the pipes above your basement, this is also the most expensive option because you need to pump waste and sewage out. If you are trying to keep costs down, then it may be a better idea to place the plumbing pipes below your basement.

Homeowners living in older houses may find that their electrical system needs a bit of upgrading. Although it can inflate your budget, making sure your electrical system meets or exceeds current system standards will help ensure that you and your family can enjoy a safe basement.

Keep the neighbours happy

Neighbours will understandably be nervous if you’re digging next to their foundations. The Party Wall Act must be complied with, which means neighbours sharing a wall must be consulted. They can request a written report answering any questions about subsidence or other issues.

Avoid complaints by talking to all neighbours about your plans before any official correspondence so they know what to expect. Digging out a new basement or lowering cellar floors means moving earth away from the site, causing more disruption.


Basements are good for

• Television/cinema room
• Games room/playroom
• Home office/study
• Gym
• Utility room
• Teenagers with drum kits
• Violin practice

And bad for

Bedrooms: fire regulations mean bedrooms must have egress windows

The Lowdown

Approximate costs for basement conversions

• £850-£1,150 per square metre with existing cellar.
• £1,650-£2,200 per sq m if existing cellar floor needs lowering (room height should be two metres minimum).
• £3,000-£4,000 per sq m if new basement has to be dug out.