Builders in Lewes

Before you think about designs, find out which body deals with planning at your address. Lewes District Council is the local planning authority for areas outside the national park, but parts of Lewes district lie within the South Downs National Park, where the South Downs National Park Authority is the planning authority. National parks also count as designated land under national planning rules, which narrows what you can build without an application. The simplest first step is to check your address with Lewes District Council, and with the South Downs National Park Authority where relevant, and ask which consents your project is likely to need. A short conversation at this stage can save you paying for drawings that later need to be changed.

Conservation areas and national parks are both Article 2(3) designated land. The Planning Portal sets out several extra limits that apply on this land, on top of the normal permitted development rules for houses. If your home is on designated land, assume that most changes beyond a modest rear extension will need an application.

• All side extensions need householder planning permission.
• Rear extensions of more than one storey need householder planning permission.
• Roof extensions, such as a dormer for a loft conversion, are not permitted development.
• Exterior cladding is not allowed under permitted development.
• The larger single storey rear extension route through prior approval is not available.

A modest single storey rear extension may still fall within permitted development on designated land, within the usual limits of three metres for most houses and four metres for a detached house. These rules apply to houses only, and they can be removed by a planning condition or an Article 4 Direction. Read our guide to extension planning permission for the wider picture, then confirm the position for your home with the council.

No published source gives extension prices for Lewes itself, so national figures are the best guide until you have quotes. Homebuilding and Renovating publishes single storey extension costs by quality of finish, and states that its main figures exclude VAT. Work on a listed building or in a conservation area may cost more where specialist materials or methods are needed.

Design fees deserve a place in the budget too. MyJobQuote says architects typically charge 5% to 12% of the project cost, and that work on listed buildings or in conservation areas can add a further 10% to 20% to fees. Homebuilding and Renovating puts a CIAT architectural technologist at 2 to 5% of build cost. A householder planning application in England costs £548 from 1 April 2026, according to GOV.UK.