Rear extension drawings in Richmond upon Thames

How the rules shape a design

Put together, these figures describe a modest rear extension, set back from boundaries where the neighbours' windows demand it, with a roof that is not used as a terrace. The guide allows a semi-detached house more depth than a terrace, so the house type is the first thing we confirm.

Where the design wants to exceed the guide, the drawings carry the argument: a section through the neighbour's window, a sun path, a view from the garden. We prefer to find that out on the survey rather than after validation.

Because the guide gives garden figures by bedroom count, we also ask how many bedrooms the house has, now or after the work, before we fix the depth.

Permitted development, prior approval or planning

Nationally, a single-storey extension can be permitted development within 3 m (attached) / 4 m (detached) beyond the original rear wall, single storey, and a deeper one can use prior approval: 6 m (attached) / 8 m (detached), single storey, height max 4 m; not on article 2(3) land or an SSSI. The prior approval depths go well beyond the council guide, so an extension lawful by that route can still be deeper than one the borough would approve on an application.

Where rights apply, a Lawful Development Certificate in Richmond upon Thames records them. Where they do not, a householder application follows, as in our planning drawings in Richmond upon Thames.

Heritage: conservation areas and listed houses

The borough has 85 conservation areas and Historic England lists 819 entries. It also holds 1 World Heritage Site.

In a conservation area the deeper prior approval route is unavailable, and materials, roof form and the view from the street are judged more closely. A listed house needs listed building consent in addition to any other route.

Decision times and outcomes

Richmond decided 1,302 householder applications in its latest published year. It granted 83.3 per cent, and 98.3 per cent were decided within eight weeks or an agreed extension.

The speed is a fact about the council's process. Whether any one application is granted still depends on the house, the neighbours and the drawings.

Cost, checking and what is included

Our drawings start at £695, VAT included and fixed in advance. They include existing and proposed plans, elevations and sections, a location plan and a block plan. A second chartered technologist checks each sheet, and we redraw at no charge if the council asks for changes.

The Building Regulations add their own limits for the new fabric: New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4. Our building regulations drawings in Richmond upon Thames show how the construction meets them.

Related drawings and neighbouring boroughs

Adding a room in the roof as well? See loft conversion drawings in Richmond upon Thames, or read about the borough as a whole at architectural drawings in Richmond upon Thames.

Across the river and over the border, the guidance differs: compare Hounslow, Kingston upon Thames and Wandsworth. Our general rear extension drawings page covers the national rules.