Basement and cellar conversions in Brentwood

Covering Brentwood

Alongside Brentwood, we also cover Billericay, Hornchurch (6 miles to the south-west) and Romford.

Homes in the East of England

The East of England has a large stock of post-war and modern estate housing alongside period homes in market towns, which makes garage conversions, single-storey extensions and loft conversions popular.

What is included in a basement conversion in Brentwood?

Everything below ground depends on keeping water out. We design the waterproofing system (usually a cavity drain membrane with a pump, or tanking) to the relevant British Standard guidance, then add insulation, ventilation, light and an escape route. New basements involve underpinning and a party wall process and are designed with a structural engineer.

Waterproofing design and installation
Ventilation, heating and electrics
Finished floors, walls and ceilings

How much does a basement conversion cost in Brentwood?

Guide prices for basement and cellar conversions, including VAT where it applies. Your fixed price is confirmed in writing after the survey.

Basement and cellar conversions	Guide price incl. VAT
Existing cellar conversion	£1,900 to £3,000 per m²
New basement excavation	£4,200 to £6,600 per m²

Do you need permission for a basement conversion in Brentwood?

In England we deal with the council’s planning team for permission or a lawful development certificate, with building control (the council or a registered building control approver) for inspections, and with neighbours under the Party Wall etc. Act 1996 where it applies.

Converting an existing cellar with no external changes usually does not need planning permission in England. Digging a new basement or adding a lightwell often does, and many councils have basement policies.

What should I think about before starting?

New basements nearly always involve the Party Wall Act in England and Wales.
A pump for the drainage system needs a battery back-up.

How does the project run?

Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.

Questions about a basement conversion in Brentwood

How much does a basement conversion cost?

Converting an existing cellar costs about £1,900 to £3,000 per square metre including VAT. A new excavated basement is around £4,200 to £6,600 per square metre.

Will my neighbours be affected?

New basements usually need party wall agreements. We handle the notices and surveyors.

Who deals with the council for a project in Brentwood?

We do. We prepare the drawings, submit planning or permitted development paperwork if needed, and arrange building control inspections.

Basement and cellar conversions in nearby towns

Learn more about basement and cellar conversions, or see every project we cover in Brentwood.