The Cost of a Basement Conversion 2021

The cost of construction has increased dramatically in light of the current pandemic, which has stretched itself out over two years at this point in time. With many supply chains struggling from the ‘pingdemic’ and staff shortages, the cost of materials has trebled in a mere handful of months. However, for basement projects, the planning and design stage can take many months to be completed, and therefore it is the perfect time to start thinking about your basement project.

The cost of a basement depends on many different factors, including the size, complexity, and individual bespoke features (e.g swimming pool basement projects). However, on average, a new basement extension costs £140k (+VAT) for projects completed by Simply Basement. This is calculated from several different components of your basement project including: the square/cubic meterage of dirt that needs to be excavated, amount the floor needs to be lowered, architectural design and planning and the materials needed. These are only a handful of the factors that influence the price of a basement.

How To Work Out the Cost of your Basement Extension

The cost of a basement is calculated using the following current rates (correct as of August 2021):

A conversion of an existing basement costs between (approx.) £1,250 – £1,550 per square meter.
If lowering the floor level and underpinning is needed, the costs could be between (approx.) £1,500 – £2,000 per square meter.
If digging a new basement space and underpinning is needed, the costs could be between (approx.) £2,200 – £3,000 per square meter.
If digging a new basement space beneath the garden is needed, the costs could be between (approx.) £1,750 – £2,250 per square meter.
Creating the lightwell and external access costs between (approx.) £5,500 – £9,500 each, dependant on finish required.
Architectural fees and structural engineer’s fees cannot be avoided and are often between £1,500- £1,800 for basic plans. A full design package is approximately £5K – 10K: this will be dependent on the number of surveys and level of detail required.
The costs of the basement conversion building regulations application costs £1,000 upwards in-line with value.
A basement conversion planning application costs approximately £200 – £250 dependant on your local planning authority.
And don’t forget VAT is added (20%) to all construction costs!

Currently, we offer a free site survey of your home if you already hold architectural plans for your basement project, please get in touch with us to arrange this with one of our surveyors. If you are yet to begin the planning stage of your basement project, please get in touch and we can advise you on the next steps for your basement.