An extension is a planning job and a building job, and in Hitchin the planning half needs answering first. We coordinate the design, appoint the structural engineer, make the building control application and build the work. We do not produce structural calculations, and we are not architects or surveyors. This page sets out what governs an extension in Hitchin.
In the Hitchin Conservation Area an extension is not permitted development
The Article 4 direction covering the Hitchin Conservation Area removes permitted development rights for the enlargement, improvement or other alteration of a dwellinghouse. It was made on 9 October 2012. North Hertfordshire has only two Article 4 directions in the entire district, and this is one of them. The other covers Stockens Green Conservation Area, so this is not a district wide rule you can assume applies to a neighbouring town.
The direction removes seven classes of permitted development in total. Among them are the provision of hard surfacing and the erection or construction of a porch where the exterior fronts a highway. It also covers the erection of gates, walls and fences fronting a highway, and painting of the exterior of a building fronting a highway. A driveway and a porch are planning matters inside that area. We confirm the designation for your address before a scheme is drawn.
Your extension is judged against a recent local plan and a new design code
The North Hertfordshire Local Plan 2011 to 2031 was adopted on 8 November 2022 and forms part of the statutory development plan against which Hitchin applications are determined. It sits alongside the adopted Hertfordshire Minerals Local Plan and Waste Local Plan.
The North Herts Design Code Supplementary Planning Document was adopted by the council on 16 June 2026. It supports Local Plan policies SP9 and D1, and sets clear, written and illustrated design requirements that new development must follow. A written code is easier to design to than a general policy, because the requirement is on the page. We read it against your scheme before submission rather than after a refusal.
What is under an extension depends on which part of Hitchin it is in
The British Geological Survey maps the bedrock beneath Hitchin town centre as the Zig Zag Chalk Formation, part of the Grey Chalk Subgroup. Over that chalk in the town centre it maps glaciofluvial deposits of Mid Pleistocene sand and gravel. Chalk and a sand and gravel cover are not the same foundation problem, and the depth of the change is what the foundation design turns on.
In the Hitchin Hill area of south Hitchin the survey also maps artificial ground. Worked Ground is mapped at the north end of Hitchin Hill and over a broad area to its west, towards Charlton, and Infilled Ground is mapped to its east. The artificial ground layer is blank along much of the Hitchin Hill road frontage itself, so it cannot be assumed for any one address. That is an argument for a trial hole rather than a rule of thumb.
Six Hitchin streets sit inside an Environment Agency flood warning area
The Environment Agency flood warning area with notation 052FWFIVHG covers Woolgrove Road, Green Lane, Purwell Lane, Brook View, Ninesprings Way and Oakfield Avenue in Hitchin. It is named Ash Brook, Ippollitts Brook and River Purwell at Hitchin, Ashbrook, Little Wymondley and Graveley.
If your address is on that list, floor levels, the ground floor build up and the drainage strategy belong in the planning case rather than in a later conversation on site. We flag it at survey and get it into the design. Applications to Hertfordshire Building Control can be made direct or through the Planning Portal, and its building control telephone number is 01438 879990.
- Full fit-out, finishing and making good
- Bi-fold, sliding and French door openings to the garden
- Roof works and structural alterations at roof level
- Wrap-around extensions and infills
- Single and double storey extensions
Why Choose GS Renovation in Hitchin
An extension in Hitchin turns on which conservation area, if any, covers the address, because the Article 4 direction over the Hitchin Conservation Area takes away the permitted development route that would otherwise apply. We establish that first, then work back through the adopted plan and the design code to a scheme that can actually be consented. From there we appoint the structural engineer, coordinate the building control application and inspections with Hertfordshire Building Control, and build the work. As a contractor we carry the ground investigation, the shell, the roof and the finish, so responsibility does not change hands halfway. GS Renovation Ltd is fully insured and registered in England, company number 14611254.
- Rated 4.9 from 31 reviews on MyBuilder
- Garden levels and access made good where the build meets outside
- Straight advice on what is and is not worth spending money on
- Registered in England, Companies House no. 14611254
- Weathertight shell reached before the fit-out begins
- Party Wall notices served for excavation near a neighbour's wall