Chelsea shares its planning authority with Kensington and almost nothing else. The housing stock is terraced, which means shared walls on both sides, rear gardens backing onto neighbours at close quarters, and a Victorian sewer network running under a great many of them. The consequence is a pre-construction period that routinely runs longer than the construction itself.
Same planning authority as Kensington, same basement policy, same conservation area framework. Conservation area density runs higher still in the core Chelsea streets. All external alterations need conservation area consent, including rear extensions, roof changes and window replacements.
The 2015 Basement Development Supplementary Planning Document applies here exactly as it does in Kensington: single storey, beneath the existing footprint, full planning application. The policy and what it permits is set out on the Kensington page.
Chelsea’s own difficulty is the terrace. Narrow sites, shared walls on both sides, and rear gardens at close proximity to neighbours. Rear extension applications draw more objections here than almost anywhere else in the borough. The objections rarely stop a well-designed scheme, but they extend the determination period, and an extended determination moves every date behind it.
The Cadogan Estate is the dominant landowner in Chelsea, and most residential leases require written estate consent before any works begin. Cadogan’s review covers scope, specification, appointed contractor and programme. Approval takes four to six weeks.
Completing works without consent is a lease breach regardless of RBKC planning approval. The two are separate permissions and one does not stand in for the other. The estate’s appointed surveyors carry out their own inspections during construction and after it, and their charges fall to the leaseholder rather than the contractor. Budget them as a named line rather than discovering them at the end, because they arrive whether or not anyone allowed for them.
Many Chelsea properties sit within three metres of a public Victorian sewer. Building inside that distance requires a Thames Water build over agreement, a statutory process entirely separate from planning permission. Discovering the sewer during excavation stops the job until the agreement is in place.
Party wall agreements here are a volume problem. A mid-terrace property commonly means three to five notices, each carrying its own two month response window, because the terrace puts adjoining owners on both sides and often to the rear. That is a different problem from Belgravia, where the difficulty is not how many neighbours there are but how long it takes to find them. Both are set out in full, because they need different planning.
Cadogan consent, Thames Water build over risk and multi-party wall agreements all load cost into pre-construction, before a single material order is placed. Professional fees for a Chelsea basement typically run 10 to 13% of construction cost.
The gap between breaking ground and completion is smaller than the gap between instruction and breaking ground. Budget the full consent chain from the start, as a fixed line item rather than a contingency.
Typical programme 22 to 36 weeks. Pre-construction 9 to 16 weeks.
The drainage and water search a solicitor runs at purchase will show the recorded position, and Thames Water publishes asset maps. Neither is complete for Victorian stock. A drainage survey traces the actual run, and on a terrace with a rear extension planned it is worth doing before anyone prices a foundation.
Because a terrace gives you adjoining owners on both sides, and often to the rear as well. Three to five notices is standard. Each one carries its own two month response window, and those windows run concurrently only if all the notices go out together.
Objections do not decide it, the council does. But rear extension applications draw more objections in Chelsea than almost anywhere else in the borough, and objections lengthen determination. Design the scheme expecting scrutiny of what the neighbours will see.
No, and one does not substitute for the other. Planning permission comes from RBKC. Estate consent comes from Cadogan, takes four to six weeks, and covers scope, specification, contractor and programme. Building with one and not the other is a lease breach.
Because the consents run in sequence rather than in parallel. Planning, party wall, structural investigation and Construction Traffic Management Plan approval all sit ahead of mobilisation. A basement that takes five months to build commonly takes nine to twelve months to reach site start.
This site uses analytics cookies to measure how it is used. Accept to allow them, or reject to keep them off. See the cookie policy.