Renovation project management in Chelsea.

A meaningful share of Chelsea's housing stock is listed, which means alterations — inside as well as out — need listed building consent alongside any planning permission. That covers things that wouldn't normally need permission elsewhere, such as removing an internal wall or changing a fireplace, and it's worth building the extra time this takes into a project plan from day one rather than discovering it once a design is already finished.

Even where a property isn't listed, it's very likely to sit within a conservation area, so front elevations, window replacement and roofline changes are all controlled. Basement excavation is common given the value of additional space in this part of London, and carries its own, more demanding planning regime with structural and party wall requirements that need specialist input from the outset.

The finish level expected here is typically a step up — bespoke joinery, natural stone, higher-end kitchens and bathrooms — which is exactly where trade-price sourcing makes the largest absolute difference, since the markup on a premium fit-out scales with its price.

Planning in Kensington and Chelsea. Chelsea is in the Royal Borough of Kensington and Chelsea, where the council says "nearly three quarters of the borough" is protected by 38 conservation areas. In a conservation area, dormers and other roof enlargements, side extensions and two-storey rear extensions are not permitted development, and the council's conservation-area Article 4 directions can also bring changes to windows, front doors, boundary walls and roof coverings under control, house by house. A borough-wide Article 4 direction has meant that basement extensions to houses need planning permission since 28 April 2016, and the council's basement policy (CL7) limits them to a single storey and no more than half of each garden, with exceptions on large sites. Our guide to permitted development in Hammersmith & Fulham, Kensington & Chelsea, Wandsworth and Lambeth sets out the national rules, what RBKC takes away and where to check your address on the council's own maps.

Choosing an architect for a Chelsea project? How to choose an architect in South West London covers ARB checks, the council planning register and the questions to ask before you appoint.

For an early budget, the extension cost calculator and loft conversion cost calculator give London build ranges by type and specification, ex VAT, before any drawings exist, as a starting point rather than a price for a listed or basement project.

Local considerations

Planning is often the first question in Chelsea, especially in a conservation area or on a listed house. The planning permission checker and the permitted development guide set out the national limits and the council pages to check; how long planning permission takes in London has the latest householder figures, and the timeline calculator puts the stages in order.

A party wall agreement is still usual on a terrace. Building control fees are published for some boroughs, but Kensington & Chelsea quotes each project; hold a contingency as well.