Are you planning a basement extension?
Posted on 12th July 2021 at 20:02
There are several factors to consider when thinking about creating an additional living space below your current home:
Is there a cellar or basement there already and does it have enough head room?
You would need to have 2.4 meters of headroom, if that is not available you will need to excavate.
If excavation is required, it is likely you will need to underpin, this will increase the costs and needs to be factored in at the beginning of the project.
At Revamp London we ask you bring us into the project at the initial stage of when you are considering getting a basement extension. We can then work with you closely to ensure the pricing is accurate from the outset.
Will planning permission be required?
Always contact your local planning authority before you start the project, but the planning portal can give useful guidelines. If you are changing the existing footprint of the building, maybe going under the garden or you are adding in a light well or access from outside via steps, planning permission will be required. If your property is in London, we would always suggest you talk to your local authority, as they tend to have varied basement policies.
Is your house semi-detached or terraced?
If you are making any structural changes to your property and you have a property attached, it is likely you will need a party wall agreement.
A BASEMENT EXTENSION TAKES TIME
Planning a basement extension takes time and you will need an experienced team to work with, At Revamp London we have a team of experts who have successfully built basement extensions in all areas of London.
Here is a good article to read from the team at Grand Designs it has some excellent examples of basement extensions and great tips to follow.
A recent basement project constructed, and project managed by Revamp London.
The property was a 3-storey terraced property in London with the added challenge of being on a hill.
The property has already been split into 2 dwellings with a joint freehold. The owners of the ground floor wished to remain in the property but had outgrown the accommodation and needed to find new space to move into.
The construction phase:
The process took time, as planning permission was required. A new light well was being installed and the existing cellar was being expanded plus the current height of the room was too low.
A conveyor belt was set up for the manual excavation of the earth being removed. New footings were put in and this had to be done systematically with the approval of the structural engineer to keep the loadings safe.
LIVING DURING THE BASEMENT EXTENSION
The family remained living above the works being carried out below. One of the benefits of having a basement extension, there is little disruption to the existing living space, although it can take up to 6 months until it can be handed back, and the stairs are put in.
When building a budget for a basement extension, considerations like the water table must be kept as a potential added extra. This can make a big difference in the amount of water that soaks in during the dig.
Creating a damp proof environment
As part of this project all the external walls had to be tanked, there are a variety of products and methods on the market, here are a couple of examples:
Permagard – damp proof and waterproof products
Hydraflex – flexible tanking membrane
IKO Hyload - tanking membrane
On this specific project the team took it through to plastered walls as the clients decided they wanted to decorate themselves.
If you are considering a basement extension, we can advise on all aspects of the build, as well as working with our architects, planners, and engineers as part of the team.
A long-term investment
A basement extension is a long-term investment, this option is more focused on improving the living accommodation rather than about making a quick financial return. The cost always out ways the return if you are making a financial judgement. The added value will be about the new space this creates for you and your family, enabling you to remain in a home you love and avoid the challenges with a London move.
If you would like to find out more about our services, please get in touch today for an initial free quotation with our inhouse basement extension expert Arthur Gaidukevics
Tagged as: Basement Extensions, House Extensions
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