Side return extension drawings in Westminster

Conservation areas, Article 4 and the listed stock

Westminster has 56 conservation areas, 10 Article 4 directions, 4,015 list entries. A large share of terraced houses sit inside one of these controls, so the permitted development limit for side extensions is a reference point, not a route.

For comparison, the national limit on boundary height is: Eaves no higher than 3 m where within 2 m of the curtilage boundary. Even an extension that meets it is likely to need an application in Westminster for the reasons above, and we plan it that way from day one rather than discovering it halfway through.

On a terrace built to one design, a side return that breaks the rhythm of a terrace draws comment even when it is tucked behind the front wall. Where the council has refused similar schemes nearby, we say so in the covering note and show how ours differs.

Protected trees and the garden behind a Westminster house

The borough holds 685 tree preservation orders across 263 mapped zones. A side return rarely touches a mature tree directly, but a neighbouring plane or lime can sit close enough for its roots to matter, and a tree in a conservation area is protected even without an order.

We note every tree within reach on the survey, and shape the foundation and drainage to stay out of the root zone where we can. If the design cannot avoid the tree, the application carries a tree report. Gardens make up 7.9 per cent of the borough's land, so private space is scarce and officers look closely at what an extension takes.

How Westminster has been deciding householder cases

The council decided 366 householder applications in its latest published year and granted 82 per cent. 79 per cent were decided in time. A grant rate in the low eighties is lower than in several neighbouring boroughs, and we read it as a sign that drawings need to be self-explanatory.

Only 10.2 per cent of households live in a house, and an average terraced property costs £1,616,250. Those who do own one tend to invest accordingly, and expect the set to be detailed to a builder's standard.

Mews houses and flat conversions

Mews houses have their own character and their own guide. A side return in a mews is unusual, because plots are tight, but alterations to the rear and to the courtyard come up often. We apply the mews guidance in the same way as the roof guidance above: read it, quote it where it helps, and draw to it.

If your home is a flat, your lease may control the garden or passage, so we check ownership before drawing. Our location and block plans page explains the red line, and planning drawings in Westminster covers the full application.

Price, structure and next steps

Side return extension drawings start at £745 including VAT, fixed before you commit, and the council fee is separate. The set includes plans, elevations, a section through the new room and a block plan.

The old flank wall comes out and a beam goes in, so we coordinate with an engineer through structural calculations. A second chartered architectural technologist checks the set, and we redraw free until approval if the council asks for changes. See also architectural drawings in Westminster, or compare Camden and Hammersmith and Fulham.