An extension is a foundation job, a structural job and a fit out inside one programme. We coordinate the structural engineer, the building control application and the trades, and build to the design issued. This page covers what an extension in Grays involves, from the ground underneath it to the plan it is judged against.
Thurrock Council publishes what building control will charge for an extension
Thurrock Council runs its own building control service for Grays, contactable on 01375 652 655 or building.control@thurrock.gov.uk. Its charges from 1 April 2026 give a single storey extension with a floor area of no more than 30 square metres a building notice charge of £726.99 plus VAT, which is £872.39 including VAT.
A first floor or second floor loft conversion of no more than 30 square metres carries the same charge, £726.99 plus VAT, or £872.39 including VAT. The charges are set on the basis that the work takes no more than 24 months from start to finish, and that the cost estimate excludes professional fees and VAT. We put the charge in the quotation rather than leaving it to arrive later.
The ground under Grays is mapped as chalk and sand, not the London Clay of much of Essex
British Geological Survey 1:50,000 mapping records the bedrock beneath Grays town centre and Grays Riverside as the Seaford Chalk Formation. Across the RM16, RM17 and RM20 postcode areas the same mapping gives chalk, Thanet Formation or Lambeth Group rather than the London Clay that underlies much of Essex. London Clay is mapped at the northern fringe of RM16, including points in Stifford Clays and around North Stifford, so it is a boundary rather than an absence.
The mapping records the bedrock beneath Little Thurrock, and beneath parts of Stifford Clays, as the Thanet Formation, described as sand, silt and clay. It records the Boyn Hill Gravel Member, a sand and gravel, as the superficial deposit beneath Stifford Clays, Little Thurrock Blackshots and Chadwell St Mary. A foundation detail carried over from a clay site is the wrong starting point here, which is why the engineer designs from trial holes on your plot.
Parts of Grays sit on ground that was dug out or filled in
Around two thirds of the Chafford Hundred site was previously used as a chalk quarry. British Geological Survey mapping records Made Ground along the West Thurrock riverside in the RM20 postcode area, and at points on the Grays riverside near the station in RM17. It records Infilled Ground at points in South Chafford, West Thurrock and Chadwell St Mary.
Older workings are part of the same picture. The dene holes in Hangman's Wood, Little Thurrock, are a scheduled monument, National Heritage List for England entry 1002156, and there appears to have been more than 70 of them at one time, dug to extract chalk and flint. None of that decides your foundation on its own. It decides how seriously the ground investigation is taken before a depth is priced.
Planning here is decided against a plan adopted in 2011 and updated in 2015
Thurrock Council's adopted development plan is the Core Strategy and Policies for Management of Development, originally adopted on 21 December 2011 and updated on 28 January 2015. The council is a unitary authority, so planning and building control for Grays sit with the same body. It states that the Core Strategy will remain its adopted statutory planning document for the borough until the new Local Plan is adopted.
A new plan is in progress. The council consulted on its Local Plan Initial Proposals from 18 December 2023 to 19 February 2024. Its Cabinet approved a new Local Development Scheme on 9 October 2024, with an administrative update in March 2025 that left the Local Plan timetable unchanged. We are contractors rather than planning consultants, so where a design needs an application we say so and build to the decision.
- Levels, drainage and landscaping made good around the new build
- Single and double storey extensions
- Steel goalpost frames where the rear wall opens up
- Wrap-around extensions and infills
- First fix and second fix plumbing and electrics throughout
Why Grays Homeowners Choose GS Renovation
An extension in Grays is settled under the ground as much as above it. We appoint the structural engineer, build the foundations to the design they issue after the trial holes, and make the building control application to Thurrock Council, which runs its own service and publishes its charge. Because planning and building control sit with the same body, there is one authority to deal with rather than two. We coordinate the applications and the inspections, and you keep one point of contact for the engineer, the groundworks, the shell and the finishes. GS Renovation Ltd is fully insured, registered in England, company number 14611254, with free no-obligation quotations.
- Permitted development checked before you pay for a planning application
- Insulation and thermal detailing to current regulations
- A dedicated project manager from first survey to handover
- Building control inspected at foundation, damp course and steel stages
- Founder-led team with 30+ years of hands-on experience
- One point of contact on the phone, not a call centre