Single and double storey extensions in Bishop's Stortford. Trusted, professional, 30+ years' hands-on experience.
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.

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.
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.
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.
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.
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.
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
Punctual, worked hard, and did exactly what he was asked and what he said he would do. Overall, a very high quality job. Will use again.
Giorgio is an excellent and intelligent workman, and with very reasonable prices! He installed a kitchen extractor fan in a complicated situation…
FAQ
Location itself is not a line on our quotation. Two Hertfordshire homes of the same age and construction get similar house extensions figures, and what separates them is condition and access at the CM23 address. GS Renovation does not charge Bishop's Stortford homeowners a premium for the address, and there is no travel surcharge within Bishop's Stortford. The survey establishes the rest. Ring 07472 424 226 with the CM23 postcode and we will confirm before quoting. As a rough guide, house extensions in London typically starts from roughly £40,000 for a single-storey rear extension and rises with size and specification (indicative London ranges, MyBuilder and Checkatrade, 2026). Your figure depends on the size, specification and condition of the property, which is why we survey before quoting.
Give East Herts six weeks' notice before any work to it. A section 211 notice is required for work on a conservation area tree with a trunk diameter greater than 75mm that is not already covered by a Tree Preservation Order. The council requires tree work to comply with BS 3998, and it can prosecute where a protected or conservation area tree is worked on without consent or the required notice. Those six weeks sit inside the programme.
Ground and water checks that a plot further up the hill does not need. The council's landscape assessment describes the Stort Meads as a finger of floodplain running from the centre of the town to the Essex boundary. The Environment Agency has recorded levels at Grange Paddocks, station 5141TH, since 1 January 1989. In the valley the mapping shows Alluvium over Chalk, and Alluvium is described as compressible silty clay. Foundation depth there follows the engineer's design.
One of two. Silverleys and Meads was designated on 4 December 2012, and All Saints, Central, South and parts of Thorley on 5 July 2014, both on the application of Bishop's Stortford Town Council. The second went to a referendum on 7 September 2017 and was approved by 2,512 votes to 680. When both were revised in 2022, the examiner found the modifications material but not a change to the nature of either plan, so no referendum was needed.
Check the volume and the appraisal list before anything else. Conservation area designation means planning permission is needed for the total or substantial demolition of an unlisted building of 115 cubic metres or greater. The appraisal also identifies 188 unlisted buildings or groups as making an important architectural or historic contribution, and says demolition of them is unlikely to be approved. Demolition is therefore settled before the new foundation is priced, because it can change the whole scheme.
Uttlesford District Council, not East Herts. CM22 is a Bishop's Stortford post town covering rural parishes, and parishes including Takeley, Hatfield Heath, Great Hallingbury, Hatfield Broad Oak, Elsenham, Henham and Ugley fall under Uttlesford for planning. The post town printed on your letters is not the planning authority. That changes the policies your drawings are tested against. We confirm the district for the address before an application route is set.
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Free, no-obligation quote for house extensions in Bishop's Stortford. Rated 4.9 from 31 reviews on MyBuilder, fully insured, and building control handled for you.