Basement and Cellar conversions

Most people need more space in their property, and many are opting for cellar conversions or having a new basement built under the existing foot print of their home. This adds both space and value to their homes and may also be less expensive than moving house.

A basement is the ideal location for additional family living space, such as a playroom, gymnasium, home entertainment room, utility room freeing up more valuable above-ground space.

Normally converting an existing cellar beneath a dwelling from a storage area to habitable space does not require planning permission. This will be covered by your home’s Permitted Development (unless you are in a Conservation Area or special designated area, or your home is a Listed Building.)

To increase the floor to ceiling height of a cellar is, however, treated as an extension and so may need planning permission. Under certain circumstances, however, modest extensions and alterations can be undertaken without the need to make a planning application. You will need to speak to your local planning department for guidance.

A self-contained flat is also an option with a newly formed lightwell and external steps thus creating its own individual entrance.

All basement conversions will need Building Regulations and in some cases Planning Permission from your local authority.

Design and Planning

A full survey of the property is carried out and a design for the proposed basement is created together with your architect and structural engineer. At this stage costings can be given for either a dry habitable basement or a dry storage basement depending on your requirements. Once a design has been agreed, the planning permission application is submitted by your architect or yourself (which should take approximately eight weeks).

Should you own a terraced or semi-detached property, whilst waiting for planning approval you will need to have a Party Wall Agreement drawn up with your neighbouring properties. Once the Party Wall agreement has been signed and planning permission has been obtained, our company will go through the scheduling of works.

Stage 1

Work on the basement is started by digging and removing any soil, with any underpinning works carried out. Steel beams are erected as required to support the structure of the existing house, following the guidance of a structural engineer. The basement excavation will involve supporting the existing foundations, internal loadbearing walls, floors and any concrete pads that may be supporting an existing extension.

Stage II

This will then be followed by waterproofing the structure and reconfiguring drain runs and existing manholes if necessary, to ensure that you are left with a waterproof shell.

Stage III

The basement will be left finished, together with the laying of a chipboard floor or floor screed, ready to receive decoration by a third party.

Should you require any electrical and plumbing fittings within the basement this is to be carried out by a third party in conjunction with our scheduling

How Long Will the Conversion Take?

A simple cellar conversion can be completed in a matter of weeks. Converting a single-room cellar using a membrane lining system can take up to four weeks, including digging out the sump and fitting the pumping system.

Converting and extending the cellar beneath an entire house, involving underpinning of the existing structure, is likely to take several months.


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