House extension drawings in Kensington and Chelsea

Gaps, flanks and access to the rear

The same policy protects things that do not show on a plan view until you look for them. Extensions are resisted where they block an important or historic gap or view, obscure features on a formal flank elevation, or reduce access to the rear of the property or its neighbours.

Conservatories at roof level, significantly above garden level or on a corner site are also resisted. A raised terrace with a glazed room above it is therefore a difficult brief here, and it is better to learn that at the sketch stage than at validation.

For a ground-floor addition, our rear extension drawings in Kensington and Chelsea go through the plan and section in detail.

Conservation areas, Article 4 and listed houses

The borough has 39 conservation areas, 84 Article 4 directions and 1,350 listed building entries. In a conservation area the permitted development right for a side extension is removed.

The council also holds 4,560 tree preservation orders and 41 tree preservation zones, so a garden tree is something to check as well as a neighbour's window. The borough has no Green Belt, at 0 per cent.

Where a house is free of those controls, a single-storey rear extension may follow the national rule: 3 m (attached) / 4 m (detached) beyond the original rear wall, single storey. A Lawful Development Certificate in Kensington and Chelsea records that in writing. Flats have no householder permitted development rights, so for a flat the question does not arise.

Houses, flats and what the borough's mix means for extensions

Only about 17 per cent of households live in a house, and 31.7 per cent own their home. Where the home is leasehold or one of several flats, the freeholder's consent can be needed as well as planning, and a party wall notice is often part of the work.

Where a protected tree stands close to the new work, the footprint is set around it before the drawings are finished, and the application explains how the tree is kept. That is easier to settle at the sketch stage than after the council has asked.

How the borough decides householder applications

The council decided 664 householder applications in its latest published year, granted 93.7 per cent and decided 91.9 per cent within eight weeks or an agreed extension. The fee for an extension to a single dwelling is £548, paid to the council and separate from our fee.

Those figures cover every householder project in the borough. We use them for planning the timetable, not to predict a decision.

What the drawings include and what they cost

A set for a Kensington and Chelsea extension shows existing and proposed floor plans, elevations and sections, plus the location and block plans. Because the council judges the rear elevation against its neighbours, we include the adjoining rear walls on the elevation and the section.

Drawings start at £695 with VAT included, are checked by a second MCIAT chartered technologist, and are redrawn at no charge if the council asks for changes. For the whole borough, see architectural drawings in Kensington and Chelsea, or compare Westminster and Hammersmith and Fulham.