Planning a Basement Conversion

Converting your basement is the best way of adding living space to your home without drastically altering the exterior. Unlike a loft conversion, it is close to the communal rooms in the house which means it’s more flexible and can be used for family spaces, bedrooms, entertaining spaces, or even running a home business.

Choosing a Type of Conversion

Your type of conversion (and whether or not you need planning permission) depends on your existing basement space and what you’d like to do with it.

If you already have a basement that’s just used for storage, you can convert it into a living space without the need for planning permission. Head height can usually be increased to a suitable level without the need for major underpinning works. These conversions are the fastest and simplest since the space is already there.

However, if your home does not have a basement it is likely that you will need planning permission – especially if you plan to add light wells to the exterior. Most of these basements are under house or retro-fitted, meaning that they are excavated directly below your property.

Our team can also create under garden basement conversions, if you require even more space. Under garden or open excavation basement conversions extend beyond the boundaries of the house to build a basement under your garden.


Retro-fitted basements are the most popular as they can almost always be added onto a home without interfering with underground pipes or experiencing issues with planning permission. These can be built as full footprint conversions (which extend through the full area of the house) and half footprint (which are about half the area of the house).

Our Basement Planning Process

Our initial meeting is at your home to discuss your requirements, intended use for the basement, and to do a preliminary check of the area. We supply a quote based on your design ideas and the survey of your home.

We can provide architect details based on your requirements who will create detailed drawings for planning consent and for our construction team to follow throughout the project. As part of the pre application planning process we recommend carrying out any necessary investigations, such as tree reports, noise surveys, and flood risk assessments to ensure that your planning application is completed in full. This saves time during the planning process and ensures that we are prepared for any eventualities once we begin excavating.

Basement Design

We work with experienced architects as well as structural engineers who will ensure your basement is totally safe and structurally sound. We can offer any level of design input you require either by our experienced design partners or input from ourselves based on past experience. We would be very happy to work extensively with your appointed professionals if you would prefer.

ANY QUESTIONS? CALL 020 3174 1241
Case Studies

Loft Conversions Add a Fifth to Property Values

Loft conversions are one of the best ways to make your home more spacious – an intelligently-designed conversion can add as much as 30% more living space to your home without extending the footprint of your house. As with all home improvements, conversions also increase the value and sale-ability of your home. A study by […]

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The client wanted to make extensive improvements to her home in Wandsworth, including a loft conversion, a kitchen extension, and alterations to her existing lounge and one of the existing bedrooms. All of the work took around 12 weeks and they were extremely happy with the results.  


Avian Construction Ltd

Peterden House
1A Leighton Rd
West Ealing
W13 9EL

020 3174 1241