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

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.
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.
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.
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.
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.
George was a great find. The job required re-plastering the walls before fitting acrylic panels. He also re-plumbed the shower waste under the solid…
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
Any change is costed and agreed in writing before it is carried out. If you add to the house extensions scope at your DA1 property, or the 1930s and interwar structure needs more than the survey suggested, GS Renovation sets out the effect on both price and programme. Work does not continue on a Dartford site until you have agreed it. Ring 07472 424 226 and GS Renovation will explain how variations are handled at a DA1 address. 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.
Kent County Council, as the lead local flood authority for Dartford, which has a Drainage and Planning Policy document setting out policies for sustainable drainage. The borough council handles the planning and building control side. That split matters because the Dartford Strategic Flood Risk Assessment identifies surface water, groundwater and sewer flooding as flood sources in the borough alongside fluvial and tidal flooding. Where the extension's water goes is a design decision, not an afterthought.
Not automatically, because not every entry is a named property. The council's published List of Article 4 Directions has 34 numbered entries. Entry 1 is Darenth Woods, Wood Lane, Darenth, and entry 33 is Land Adjacent Stanley Cottages, Green Street Green Road, Dartford. Entry 34 is not a property at all, but the direction for houses in multiple occupation covering the borough north of the A2. Read the list and that direction together.
It has to respect what the area's appraisal identifies as characteristic, which is not the same thing as copying the house. The Dartford Town Centre Conservation Area Appraisal records yellow brick walling generally laid in Flemish bond as a characteristic historic material, with slate and occasionally pan tile roofs. That area is the largest in the borough and contains approximately 40 listed buildings and structures. Materials are agreed with the council through the application.
In parts of the borough, yes. The Dartford Plan to 2037 describes the built up areas of Dartford, Greenhithe, Stone and Swanscombe as interspersed with former chalk quarries and industrial land, and the town centre appraisal records large chalk pits on West Hill and Overy Street. Deneholes, chalk shafts with chambers opening off the base, are a documented feature of the chalk in north Kent. Ground investigation comes before any foundation design.
The guidance is written for semi-detached and terraced properties on a common boundary, so a detached house is not named in it. That does not put a detached house outside the plan. Design is assessed against Policy M1 of The Dartford Plan to 2037, titled Good Design for Dartford, and the plan adopted on 22 April 2024 is the document your application is judged against. Your designer settles the depth with the council.
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Free, no-obligation quote for house extensions in Dartford. Rated 4.9 from 31 reviews on MyBuilder, fully insured, and building control handled for you.