House Extensions Berkhamsted

An extension is planning, building regulations, structure and finish in one job. We coordinate the structural engineer, make the building control application, and build the shell and the interior. We are not architects or planning consultants, and we say when you need one. In Berkhamsted two things are worth knowing early: what the levy on new floor space costs here, and what has to be inside the application for it to be validated at all.

For Berkhamsted, 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 Berkhamsted: the structural engineer we appoint designs the structure, we build it, and building control signs it off.

Berkhamsted sits in the borough's highest Community Infrastructure Levy zone

Dacorum's adopted Community Infrastructure Levy Charging Schedule places Berkhamsted in Zone 1, described as Berkhamsted and surrounding area, at a residential rate of £250 per square metre. That is the highest of the four charging zones. The comparison is £150 in Zone 2 elsewhere in the borough, £100 in Zone 3 covering Hemel Hempstead and Markyate, and £0 in Zone 4 for identified sites.

Dacorum states that an extension is not liable if it creates less than 100 square metres of new floor space and is not a whole new dwelling or an annexe. The council also states that annexes are liable whatever the size. In Berkhamsted that means the Zone 1 rate applies to a granny annexe however small, which is worth knowing before the drawings are drawn.

Housing in Berkhamsted

Count the homes in Berkhamsted and you get about 8,290: 71% built since 1945, 12% between the wars and 17% before 1919, with flats at 25% and houses at 75%. 28% of homes here are detached; a detached house in Berkhamsted often extends far enough from the boundary that no party wall notice is needed.

What has to be in the application, and when to claim relief

Dacorum Borough Council states that it does not currently have any additional local validation requirements, so a Berkhamsted planning application follows the national list of required documents set by Government through the Planning Portal. It also states that Community Infrastructure Levy additional information forms must be included with a planning application, and that applications submitted without these forms will not be validated.

Timing matters on relief. The council states that claims for exemption or relief must be made before any development starts on site, including any demolition of existing buildings. We build that into the programme, so nothing is knocked down before the paperwork is in and acknowledged.

Berkhamsted is outside the Chilterns National Landscape, with Green Belt to the north

The built up area of Berkhamsted lies outside the Chilterns National Landscape. The designated land wraps around the town on several sides, including Berkhamsted Common to the north, land to the east, and land to the southwest towards Northchurch. That catches out people who assume the National Landscape covers the town itself.

Green Belt land begins immediately north of the built up area, forming part of Dacorum's section of the London Green Belt. If your property sits on that edge, the extension is judged against a different set of policies, and the size and siting questions become harder. We flag it at the first visit rather than after a refusal.

How a rear extension is judged here

Visibility is one test, and it is not obvious from the front of the house. The Berkhamsted Conservation Area Character Appraisal records that the houses on Station Road stand on narrow but very long plots that stretch down to the towpath of the Grand Union Canal. It records that Ellesmere Road is built up on one side only, with the railway opposite the fronts of the properties. Extensions at the rear of houses there, and rooflights added to rear roof slopes, can be seen across the rear gardens from Paxton Road and from the end of George Street.

Scale is the other test. Dacorum's design guidance for Berkhamsted states that the predominant scale in the residential streets is two storeys, and that two storeys with an attic is not the same as three storeys. We use that language when we talk options through with you, because it is the language the decision will be made in.

Kitchen extensions in Berkhamsted

64% of the houses in Berkhamsted 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 Berkhamsted; the build figures are in the table above.

Side return extensions in Berkhamsted

Side returns belong to Victorian and Edwardian terraces, and only 17% of homes in Berkhamsted 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 Berkhamsted

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 Berkhamsted often needs planning permission from Dacorum Borough Council. With 48% 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.

• Foundations, groundworks and steel frames
• Steel goalpost frames where the rear wall opens up
• Brickwork and mortar matched to the existing elevation

VOA Council Tax stock of properties, March 2025, for Berkhamsted Town, Berkhamsted West and Berkhamsted South. Counts rounded by the VOA.

Plenty of Berkhamsted projects start with one job and grow, so it helps to see RSJ and steel beam installation in Berkhamsted, house extensions in Tring, double storey extensions, a garage conversion instead, house extensions across London and Garage Conversion Cost.

The GS Renovation Difference in Berkhamsted

An extension in Berkhamsted carries the borough's highest levy rate on new floor space, and a relief claim that has to be made before anything is demolished. We build the sequence around that, so the order of events protects you rather than costs you. We appoint the structural engineer and build to the calculations issued, coordinate the building control application and inspections, and run one programme with one point of contact for every trade on site. Quotations are free and without obligation. GS Renovation Ltd is fully insured and registered in England, company number 14611254.

• Programme planned around party wall notice periods before excavation near a neighbour
• One point of contact on the phone, not a call centre
• Foundation depth set after trial holes, drains and trees are checked

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.