Basement extension is a great way to gain more functional space and get the maximum benefits from the extension process. At the same time, it is possible to increase the property value, typically by around 20% of its value.
Creating a space underneath your house can be a really cost-demanding process, especially if excavation and damp-proofing is required, as it is more expensive per square meter than a common above-ground extension.
There exist two main ways of using the space under your property and making it a habitable environment:
- renovation of existing basement or cellar;
- new basement construction underneath the house.
Each of these cases has its peculiarities which influence the costs significantly. Let’s consider all the factors in detail, so that you can avoid surprising and unpleasant situations once the process has already started.
Conversion of an existing cellar is not as expensive and may cost approx. £750 – £1,400 per square metre. It is necessary to take into consideration the features of the existing structure of the basement, the number of walls which will be built, individual installations and flooring design.
Factors that may increase costs include moving services, especially in the case of poor access to the site, underpinning of the existing structures if necessary, water-proofing, etc.
As for the new basement construction, costs may can vary significantly and usually include the following constituents (approximate costs per square metre):
- Planning and Building regulations applications (£750 – £1200)
- Party wall agreement (£700 per each neighbour)
- Engineer fees (£1000 – £1500)
- Floor level lowering and cellar underpinning(£1500 – £2000)
- New basement space excavation (£1500 – £3000)
- Lightwell and external access construction (£5000 – £7000)
- VAT contractors additional fees may reach up to 20%.
To sum up, a shell place construction will cost £1,920-£2,640 per square metre. If you have an already existing cellar, converting it will cost £720-£1,800 per square metre.
All the above listed figures are approximations and may vary considerably depending on a number of factors. Moreover, they don’t take into account the design and interior or exterior finishes: wall painting, furniture, flooring, additional fittings or any other decorating ideas.
Diamond Construction Ltd always adjusts the costs to the customer’s budget capabilities, without lowering the standards and quality of our work.