October 21, 2016

Converting your basement is a great way to create more space in your home without a) changing its outward appearance and b) losing any of your outdoor space. However, converting a basement is still a major undertaking and requires lots of planning and skill to execute properly. In this blog post we’re going to take a look at three of the most important components, from a structural engineering perspective, to ensure your basement stays safe and dry.

Planning permission and other regulations.
Converting an existing, residential basement or cellar into a living space is unlikely to require any planning permission. This type of conversion should be covered under your property’s ‘Permitted Development’, although listed properties or those built in a conservation area may be subject to different rules.

Other regulations to consider are ‘The Party Wall Act’ which provides a legal framework for preventing and resolving any boundary, part walls or excavation disputes from your neighbours. Unless you live in a detached property with no neighbours, you will need to come to an agreement with the people living around you prior to work commencing.

As with any build you must comply with Building Regulations. Some basements and cellars may require underpinning, as an example, this may also require the floors to be dug deeper to reach a sufficient head height. Because of this, structural supports such as steel beams may need to be added, however this is something your architect and/ or surveyor should advise you on. Any structural work like this will need to be signed off by a local authority to ensure that there will be no further impact on the rest of your house or your neighbours properties.

How much work is required to convert my basement, and can I do it myself?
Converting a basement or cellar always comes with its own complications. Depending on what you intend to use the space for there may be more work than initially imagined. In most basements headroom is the first obstacle to overcome as typically, underground spaces have lower ceilings, meaning excavation work will need to be carried out. This is unlikely to be something you would be able to undertake yourself, and something we would strongly advise against!

The other key part to the success of any basement conversion is keeping out the water. Proper basement waterproofing must be implemented to ensure the damp stays out. Working with your architect to find the best partner to manage this is vital as a basement with a damp problem can be expensive and dangerous.

Is converting a basement expensive?
As with any conversion there are varying costs, but on average a basement conversion (from an existing cellar or underground space) is likely to cost between £450 – £650 per m² to get it to the first fix stage (a shell space with concrete walls and floor ready for the first fix i.e. wiring and plumbing) from there really the sky is your limit. If you’re looking to create an underground space from scratch, perhaps under an existing extension, then you will need to budget for significantly more work including excavating, underpinning, temporary works and much more. A typical budget for this type of work should start at between £1,600 – £2,200 per m² to get you to shell space.

Converting a basement is a fantastic way to gain more space from your home, however it is a project that requires a lot of skill. Working with the right architect and putting together the right team of structural engineers, damp proofers, builders, plumbers, lighting designers etc… is no small task.

We have worked on a number of basement conversions and know how to help with planning, design, temporary works and structural surveys so talk to an expert here, to get your basement conversion underway.