House Extensions Bishop's Stortford

An extension is a foundation, a structure, a roof and a set of consents that all have to line up before anything is built. We build to a structural engineer's calculations and coordinate the building control application and inspections. We are not architects, engineers or surveyors. This page sets out the consent tests and the ground conditions that shape an extension in Bishop's Stortford.

For Bishop's Stortford, on London-derived ranges a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m²; Hertfordshire work generally runs below that. GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Bishop's Stortford: the structural engineer we appoint designs the structure, we build it, and building control signs it off.

In the conservation area, several kinds of extension need planning permission outright

East Herts guidance for owners and occupiers states that permission is required for a house extension to the side, and for an extension greater than single storey. The same guidance lists the cladding of any part of the exterior, and any addition and some alterations to the roof.

On top of that, the Bishop's Stortford householder Article 4 direction withdraws Part 1 Class A, the enlargement, improvement or other alteration of a dwellinghouse, on elevations or areas facing or visible from a highway, open space or waterway. The same direction withdraws Class D for porches, Class E for buildings and enclosures within the curtilage, Class F for hard surfaces and Class H for microwave antennae, each on that same visibility test.

Housing in Bishop's Stortford

The Council Tax list puts Bishop's Stortford at about 20,560 homes, 20% flats against 79% houses; 12% went up before 1919, 7% between the wars and 81% after 1945. 30% of homes here are detached; a detached house in Bishop's Stortford often extends far enough from the boundary that no party wall notice is needed.

Your application is judged against a district plan and a neighbourhood plan

The East Herts District Plan was adopted on 23 October 2018 and sets the framework for the period 2011 to 2033. Policy HA4 requires alterations and extensions in a conservation area to be complementary and sympathetic to the parent building, and to use materials and design details that are traditional to the area.

Policy DES4 requires development proposals, including extensions, to avoid significant detrimental impacts on neighbours through inadequate daylight, privacy or overshadowing. Two made neighbourhood plans also form part of the East Herts development plan here: Silverleys and Meads, and All Saints, Central, South and Parts of Thorley. Both were revised and formally made again in July 2022, so the current versions are the ones your drawings are tested against.

The ground an extension foundation meets changes across the town

Over Thorley Park, St Michael's Mead, Hockerill and the ground south of the town centre, British Geological Survey mapping shows the Lowestoft Formation, recorded as a diamicton. The survey describes it as an extensive sheet of chalky till, characterised by its chalk and flint content, with a carbonate content in the till matrix of about 30 per cent.

Over the Market Square area, and northwards towards Northgate End, the mapping shows Head instead. The survey describes Head as poorly sorted and poorly stratified angular rock debris, or clayey hillwash that has crept down a hillslope, made of gravel, sand and clay depending on the source upslope. Foundation depth is set by the engineer from what the trial hole shows, so we dig and record that hole before the substructure is priced.

Parts of this town were dug for clay and fired for brick

Late 19th century mapping reproduced in the conservation area appraisal identifies a kiln, a brickyard and a clay pit immediately east of the former Nonconformist School, now part of Bishop's Stortford College, off Hadham Road. The appraisal also records that there were clay pits on the Dunmow Road, in the Hockerill part of the conservation area.

A 19th century directory quoted in the same document lists a large brewery, malting establishments, brickfields, a foundry, coach and sacking works, lime kilns and gas works among the industries then operating. None of that tells you what lies under one particular garden. It tells you why a trial hole is dug before a foundation is priced, rather than after.

Kitchen extensions in Bishop's Stortford

70% of the houses in Bishop's Stortford are semi-detached or detached, which usually leaves room for a kitchen extension across the full rear width, with a steel beam over the opening into the house. The fit-out is priced on its own page, kitchen renovation in Bishop's Stortford; the build figures are in the table above.

Side return extensions in Bishop's Stortford

Side returns belong to Victorian and Edwardian terraces, and only 12% of homes in Bishop's Stortford predate 1919, so they are the exception here; most extensions run across the full rear width instead. Our side return extension page covers the build in detail, with build rates of £2,400 to £3,200 per m².

Double storey extensions in Bishop's Stortford

Under permitted development a two-storey rear extension can go no more than 3 metres beyond the original rear wall and must stay at least 7 metres from the rear boundary, and in a conservation area it is not permitted development at all. Many gardens are too short for the 7 metre rule, so a double storey extension in Bishop's Stortford often needs planning permission from East Herts District Council. With 55% of homes here semi-detached or detached, the side of the house is often an option too. Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.

• Wrap-around extensions and infills
• Drawings and the structural engineer's design coordinated for you
• First fix and second fix plumbing and electrics throughout

VOA Council Tax stock of properties, March 2025, for all 5 statistical areas in Bishop's Stortford. Counts rounded by the VOA.

Once you know the scope of the house extensions in Bishop's Stortford, it helps to read RSJ and steel beam installation in Bishop's Stortford, house extensions in Harlow, side return infills, a garage conversion instead, how we handle house extensions across London and Party Wall Act Explained.

The GS Renovation Difference in Bishop's Stortford

An extension in Bishop's Stortford is decided twice before it is built. Once on planning policy, where a district plan and a made neighbourhood plan both apply, and once on the ground, where the foundation design follows what the trial hole shows. We handle the build and the coordination around it. We appoint the structural engineer, build to the calculations issued, and make the building control application and book the inspections through each stage. GS Renovation Ltd is fully insured, registered in England under company number 14611254, and rated 4.9 from 31 reviews on MyBuilder. Quotations are free and without obligation.

• Garden levels and access made good where the build meets outside
• Photographs kept at each stage for your records
• Brick and mortar matched to the existing elevation

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.