Builders and plumbers in Dartmouth Park, N19

Camden’s conservation-area page for Dartmouth Park publishes a topography map alongside the townscape and urban-grain maps. That map is a useful first reference, and ground levels are then confirmed on site for the exact address. Where a plot slopes, rear gardens can fall or climb away from the house, and a cellar on the uphill side can sit hard against soil.

We treat levels as part of the engineering. A survey here records levels at the front, the rear and each boundary, not just the internal floor. It notes where the ground is higher than the floor and where a garden wall is also a retaining wall. It records where surface water from the street could reach the house. Cracks, sticking doors and damp on the uphill side are read against the levels before any cause is assumed. Neighbouring floor levels are noted where they can be seen.

Where gardens sit at different levels, the wall between them often holds one of them back. GOV.UK’s party-wall guidance treats a garden wall standing on the land of two or more owners as a party wall. Notices and agreement can therefore apply to repairing or rebuilding it, and excavation close to a neighbour’s structure also falls within the Act. The first task is to establish who owns the wall and who benefits from it.

The second is water. A retaining wall can fail from behind when the soil it holds becomes saturated and drainage behind the wall is absent or blocked. Signs include bulging, leaning, open joints and damp patches on the lower face. Repair starts with drainage and weep holes, then the wall itself, using materials that match the original where the area’s character depends on it.

Camden’s basements page states that any proposal with a new or extended basement must be supported by a Basement Impact Assessment specific to the site. It must cover drainage, flooding, groundwater and structural stability. The Local Plan of 2017 includes policy A5 on basements, and Camden Planning Guidance on basements was adopted in March 2018. The council generally requires an independent technical audit of the assessment, and it publishes a help note on the scope of engineering input.

On a slope these requirements bite harder. Groundwater may move through the site rather than sit under it. Neighbouring houses may be founded at different levels, and a retaining wall may already be doing structural work. The assessment has to show that the new structure will not change how water or load moves through the hill. We build that evidence stage into the programme.

On a sloping Dartmouth Park plot, damp is often a drainage problem. Surface water can run down the street and gardens and collect against the uphill face of a house. It then finds its way through brick that was never meant to be a tanked wall. Blocked gullies, disconnected pipes and garden levels raised above the damp-proof course are common causes. A cellar that has long been dry can turn wet after a neighbouring garden is paved.

Diagnosis follows the water. We check gutters, outlets and gullies and measure external levels against the internal floor. We look at how neighbouring plots drain, and only then consider tanking or membranes. New or altered drainage can need Building Regulations approval, which GOV.UK describes as different from planning permission. A membrane inside a wet wall without dealing with the water outside is a delay, not a repair.

Camden adopted the Dartmouth Park conservation area appraisal and management strategy on 22 January 2009. It added supporting guidance on energy efficiency for the area on 23 August 2012. The council’s heritage Article 4 register carries only one Dartmouth Park entry: a single-property direction from 1980 preserving a painted sign on a flank wall in York Rise. It does not list a general direction for the area, though other directions can exist and the position must be confirmed for the property.

The general rule from the council’s conservation-areas page still applies: alterations usually need planning permission and applications must carry a heritage statement. Tree work in a conservation area needs prior notice to the council. Listing is checked separately on Historic England’s list. The energy-efficiency guidance is worth reading before windows or roofs are considered.

Camden formally adopted the Dartmouth Park Neighbourhood Plan on 2 March 2020, following a referendum. A minor correction was made in August 2022 to a Local Green Space boundary at the Mansfield Bowling Club. The council’s page links the adopted plan and the application that defined the neighbourhood area. The forum was redesignated in December 2018 so it could continue its work.

For a homeowner the plan is context, not consent. Applications within the area are weighed against its policies alongside the borough’s Local Plan, and reading them early helps a design answer the right questions. It cannot approve an extension, a basement or a roof change on its own. Nor does it remove the need for Building Regulations approval or party wall agreement. We check whether the property lies within the area and cite relevant policies where they help.

A slope changes site set-up. Scaffolding needs base plates and sole boards set to the gradient, and a scaffold standing on a council road needs Camden’s building licence. A skip on the carriageway needs a licence applied for by the skip company, and a suspension for any bay it takes. On a gradient, its position is agreed with the driver so loading stays safe. Where a front garden sits above the pavement, steps limit what can be carried in one lift.

Deliveries are planned for the street, not the catalogue, with small vehicles and short windows. Tufnell Park and Kentish Town, both on the Northern line, serve trades arriving by Tube. Materials for rear-garden work often have to come through the house or over a retaining wall, so protection and lifting arrangements are agreed in advance.

On a sloping plot, the most useful record shows what cannot be seen afterwards. Drainage runs, soakaways, weep holes, membranes, wall ties and the foundations of a rebuilt retaining wall are photographed before they are covered. Each image carries a scale and a location reference. Levels measured at the survey are recorded against the finished work so future movement can be judged. Where a Basement Impact Assessment or monitoring applied, the reports and any conditions discharged sit in the file.

The usual records follow: scope, variations, product data, test certificates, planning decisions, party wall awards and schedules of condition. A short maintenance note on gullies, gutters and the ground behind the retaining wall is valuable here. A blocked gully or weep hole is an easy failure to prevent. Keeping the record against the exact address means the next owner or contractor can read the ground as we did.