Wraparound extension drawings in Kensington and Chelsea

Basements, trees and foundations

The Basements SPD matters even when you are not building a basement. If the wraparound lowers the ground floor or adds a lower level, the council may treat the work as basement development, which can bring a construction method statement and a structural report.

Trees add a second layer. With 4,560 orders in a small area, a garden tree may well be protected, and a rear wall near it needs foundations that leave the roots alone. A tree survey at the start prevents a request for one at validation.

What the figures show

93.7% of householder applications were granted, and 91.9% were decided in time. That grant rate is a reason to draw carefully, not a reason to relax.

Use of the shorter routes is almost nil: larger home extension prior approvals show 0 granted and 0 refused in the latest return year, and only 25 Lawful Development Certificate applications were recorded. A full householder application, with a council fee of £548, is the realistic route.

Domestic gardens cover 17.5% of the borough, and in a dense borough each rear garden is a scarce amenity, so the garden left after a wraparound is judged closely.

Value, levy and the drawing set

The average home sells for £1,232,640, so a wraparound is a serious investment and the drawings need to be precise. Borough CIL runs by zone, from £1,158.30/m² (Zone A); £911.20/m² (Zone B); £664.09/m² (Zone C); £416.99/m² (Zone D); £293.44/m² (Zone E); £169.88/m² (Zone F); Nil (Zones G Earl's Court and H Kensal), and the Mayoral CIL band is 1 at £96.97 per square metre indexed. Levies generally apply to larger additions, but the borough rates are high enough that we measure carefully.

The set has surveyed existing plans, proposed plans, elevations, sections, a roof plan and a heritage note. If a smaller scheme would do, see rear extension drawings in Kensington and Chelsea.

Neighbours need party wall notices, and our other work in the borough is at architectural drawings in Kensington and Chelsea. If the council asks for changes before it decides, we redraw them free of charge.

Design details for a Kensington and Chelsea house

Materials and joinery carry the case here. London stock brick that matches the host, lime-based pointing, timber or slim steel glazing with proportions taken from the existing windows, and a roof edge that does not show from the street all help an officer see continuity with the house.

We draw the junction between old and new at a large scale, because that detail is where conservation officers look first. Rainwater, flashings and the line of the old rear wall should be legible in section.

Listed houses and what to ask first

If the house is listed, a separate consent is needed beside planning permission, and the original plan form carries more weight than any new room. We read the list entry and the history before we draw, and will tell you honestly if a wraparound is unlikely to be accepted.

For any house in the borough, the useful questions come in order: is the house listed, is it in a conservation area, is there a protected tree, and does the work touch ground level? The answers shape the scheme and the budget before a line is drawn.