House Extensions Dartford

GS Renovation builds extensions in Dartford, working to the approved drawings and to structural calculations produced by others, then coordinating the building control application and inspections. We are a contractor, not an architect and not a structural engineer. What The Dartford Plan to 2037 says about depth, setback and roofs shapes the scheme long before a spade goes in. Abdelaaziz Saaid brings over 30 years of hands-on experience.

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

How deep a rear extension can go in Dartford

The Dartford Plan to 2037 sets a clear expectation. It states that single storey extensions to the rear of semi-detached and terraced properties should generally not be greater than 3.5 metres in depth on a common boundary. Anything larger has to be demonstrated to have no adverse impact. The plan was adopted on 22 April 2024, so it is the current document your application is judged against.

Two storeys is a stricter test. The plan states that two storey extensions to the rear of semi-detached properties should be set in 2 metres from the common boundary at first floor level. For terraces it states that two storey rear extensions cause particular problems and will not normally be allowed, unless it can be established that there will be no undue impact on adjoining properties.

Housing in Dartford

The stock in Dartford runs to roughly 26,860 dwellings, 27% of them flats and 73% houses, built 15% before 1919, 24% between 1919 and 1939 and 60% after 1945. A rear extension on a terrace in Dartford digs foundations close to both neighbours, so notices to both are normal, and 37% of homes here are terraced.

Side extensions and dormers are judged on how they meet what is there

The plan is specific about both. It states that two storey side extensions within 1 metre of a common boundary should generally have their front walls set back at least 0.45 metres at the point where it joins the existing building. It also states that roofs on side extensions must match and tie into the existing roof, stepped down from the main ridgeline, unless that is not possible structurally or the proposed roof would look better.

Loft conversions get the same treatment from above. The plan states that flat roof dormer extensions are unlikely to be appropriate on front roof slopes, or on roof slopes that are visible from public vantage points. Dormers at the rear should be set in to the roof plane, down from the ridgeline and in from the side cheeks. Design is then assessed against Policy M1 of The Dartford Plan to 2037, titled Good Design for Dartford. We build what is approved, and we say plainly at the survey when a detail on a drawing will not build the way it has been drawn.

The ground varies between one part of Dartford and the next

It is mapped, and it is not uniform. British Geological Survey 1:50,000 mapping records the bedrock beneath Dartford town centre as the Seaford Chalk Formation. The superficial deposit through the town centre, along the line of the River Darent, is Alluvium, classified as silt. A foundation designed for one of those is not a foundation designed for the other.

Away from the valley floor it changes again. At West Hill the mapped superficial deposit is the Boyn Hill Gravel Member, a sand and gravel, over Seaford Chalk bedrock. At Dartford Heath it is Head, sand and gravel laid down on subaerial slopes. Around Church Hill in Wilmington it is the Taplow Gravel Member. Foundation depth follows a trial hole and an engineer's design, not a map and not a neighbour's job.

Article 4 directions in Dartford are drawn house by house

The council's published List of Article 4 Directions contains 34 numbered entries, and 14 of them are individual properties on West Hill, Dartford. The list names 31, 33 and 35 West Hill as entries 2 to 4, and 73, 75, 77, 79, 81, 83, 85 and 87 West Hill as entries 22 to 29. Permitted development on that street therefore depends on the house number.

Greenhithe accounts for 17 entries, 16 of them on High Street and one at 1 Pier Road. Where a direction applies, work that would otherwise be permitted development needs planning permission instead. So the first task is to check the address against the published list rather than assume, and that check comes before a quotation means very much.

Kitchen extensions in Dartford

51% of the houses in Dartford are terraced. On a terrace the kitchen extension is built out from the back, into the side return where the house has one or across the full rear width, and a steel beam takes the old back wall so the kitchen and the new room become one space. The fit-out is priced on its own page, kitchen renovation in Dartford; the build figures are in the table above.

Side return extensions in Dartford

Side returns belong to Victorian and Edwardian terraces, and only 15% of homes in Dartford 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 Dartford

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 Dartford often needs planning permission from Dartford Borough Council. On the 37% of homes that are terraced, the neighbours' windows usually decide the depth. Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.

• Foundations, groundworks and steel frames
• Drainage diversion and build-over agreements with the water authority
• Brickwork and mortar matched to the existing elevation

VOA Council Tax stock of properties, March 2025, for all 7 statistical areas in Dartford. Counts rounded by the VOA.

Once you know the scope of the house extensions in Dartford, it helps to read RSJ and steel beam installation in Dartford, house extensions in Grays, wraparound extensions, party walls and extensions, house extensions across London and Side Return vs Rear Extension.

Why Dartford Homeowners Choose GS Renovation

An extension in Dartford runs through two separate consents, and they are not the same conversation. Planning is judged against The Dartford Plan to 2037 and settled by your designer with the council. Building control is a separate application with its own inspections, and that is the one we coordinate, including the stages that have to be seen before they are covered. GS Renovation builds to the approved drawings and to the engineer's calculations. Abdelaaziz Saaid is your one point of contact, and we are fully insured.

• Scaffolding and site set-up planned for tight terraced plots
• Honest updates if a date or a detail has to move
• 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.