Basement conversions are an alternative to loft conversions and extensions that are becoming increasingly popular in urban areas where space is in short supply. Thanks to improvements in waterproofing methods, transforming your existing cellar space into a comfortable new living area is an economically viable option to increase the size of your home and the value of your property.
Why get a basement conversion?
The obvious answer is the need for more space. Families grow, needs change, and suddenly a utility room, a new bedroom or extra living space becomes a necessity. Unlike loft conversions and extensions you are less likely to need planning permission and you don’t lose external space – converting your basement uses space already there without eating into your garden like an extension or conservatory would.
The stars are leading the way with basement space being converting into indoor swimming pools, gyms and cinemas, but besides this basement conversion is suitable for rooms that simply couldn’t be put in a loft – consider for example a new utility room or kitchen. Or the space could be used as a television or games room, a children’s playroom or a home office.
Is my property suitable for a basement conversion?
If you have an existing cellar then a basement conversion could be a cheap and easy way to extend the space and value of your home. If the space is already adequate it may simply be a case of waterproofing and improving ventilation. Even if you don’t have an existing cellar, a basement conversion could be a feasible option in city areas where space is limited and property value is very high, for example London. Some houses may not be suitable, for example modern terraced houses that are built on a raft foundation and modern town houses that are difficult to build underneath due to their tall, narrow structure. If you are unsure then seek advice from a specialist company who will be able to tell you if your basement conversion is possible.
Do I need to obtain planning permission for my basement conversion?
If you are not changing the property structurally then you won’t need to get planning permission but if you are affecting the outer structure – for example adding light wells or windows – you will. Similarly if you are digging out a basement, then you will need to get planning permission as well as drawing up a formal party-wall agreement with your neighbours if you live in a terraced or semi-detached house. If you are unsure it is best to check with your local council.
It is important to consider building regulations when planning your basement conversion, for example escape routes and ventilation, if you are planning to build a bedroom it is a legal requirement that bedrooms have windows for fire safety. Electrical wiring and water supplies will also need to be properly installed by a professional.
How will my basement be waterproofed?
Thanks to technological improvements, waterproofing basements has become more cost-effective and therefore more viable as an option to maximise space in the house. Methods include tanking which is structural waterproofing, or more commonly using a polyethylene membrane installed in a cavity between the existing structure and the new wall: water collects on the outer side of the wall and then runs down to gutters where it is pumped away. Be aware that this method of waterproofing, although highly effective, does require maintenance of around £125 a year and the pump itself will probably need replacing every ten years. Damp proofing is a crucial aspect of a basement conversion; don’t cut corners because in the long run you will run into problems that will prove more costly.
How much does a basement conversion cost?
The cost of basement conversions varies depending on the property, location and existing basement. On average it costs between £850 and £1,150 per square metre in a house with an existing basement and between £3,000 and £4,000 if the basement needs to be dug out first. A typical conversion for a terraced house in London costs around £90,000 to £120,000. It also depends on whether or not you decide to do part of the work yourself or hire a company to guide you through the whole process. Many basement conversion companies offer structural shell and waterproofing service that then allows you continue DIY with the room design and decorating.
Basement conversions, especially ones where the space needs to be dug out, are not necessarily a cheap option, however considering the return on the space created in the increase in property value it is still a worth while investment in high value urban areas and a great way to increase your family’s living space.