House extension architects in Leeds

How far back can a Leeds extension project, according to the council's guide?

Leeds City Council's Householder Design Guide is an adopted supplementary planning document, and the council's planning page says householder approval depends on meeting it (Householder Design Guide). The PDF carries an April 2012 date, so some of its policy references have moved on, but the council still names it as the test for householder approval. On a boundary shared with a neighbour, it treats a projection of about 3.0 metres as normally acceptable at ground level and about 1.0 metre at first floor, adding that a shorter reach may be needed where the neighbouring garden is short or its windows are close.

What are the 45 degree and 12 metre codes?

Both are tests the guide applies to a neighbour's main habitable windows. For the 45 degree code you find the nearest edge of the closest neighbouring window, draw a line from the house wall at 45 degrees, and keep the extension inside the permitted zone; one that strays into the other zone may be refused. The 12 metre code concerns a blank gable wall facing a window and is mostly used for two-storey work. The guide says neither code guarantees approval and neither accounts for level changes between gardens. An architect should draw both on the plans before the design is fixed, because they, more than style, decide how big the extension can be.

Side extensions, garages and parking

The guide expects two off-street parking spaces, so an extension over a driveway often needs a replacement garage or another parking area. It does not look kindly on front-garden parking that removes most of the planting or adds significant surface water run-off. Keep a note on bins too: if they sit in view of the street, the council may ask for screening.

Housing age gives a hint about which of these rules bite. Of Leeds Council Tax homes, 28.1% date from 1945 to 1972 and 18.6% from 1919 to 1939 (VOA, 31 March 2026). Many post-war and inter-war semis stand in the kind of regular semi-detached street that the guide's 1.0 metre and 2.0 metre side rule addresses, while pre-1919 terraces can raise rear-outrigger and party-wall questions instead. Our page on party wall agreements covers the latter.

Green Belt, conservation areas and listed houses

In the Green Belt the guide adopts a threshold of roughly 30% added volume on the original house, calculated from the house as built or as it stood in 1947, whichever is later. Past that, it treats a scheme as inappropriate development unless very special circumstances exist. Check whether your address is in the Green Belt before the brief is written.

The council lists 80 conservation areas. In them it says permitted development rights are restricted and that small extensions, roof extensions and cladding need planning permission (Leeds conservation areas). The national rules agree: in a conservation area every side extension, and any rear extension of more than one storey, needs an application (Planning Portal). Our national page on house extensions explains the permitted development limits that apply elsewhere.

What does the Leeds application process involve?

1. Decide whether to pay for advice. House extensions cost £156 including VAT and are answered on a target of 20 working days; a listed house costs £216 and 25 working days. Advice covers a single option and does not bind the council (pre-application service).
2. Prepare the drawings to the local list: block plans at 1:100 or 1:200, floor plans and elevations at 1:50 or 1:100, and sections where the ground slopes (validation requirements).
3. Add conditional items: a flood risk assessment in flood zones 2 and 3, a bat survey near roosts, and a tree plan where a Tree Preservation Order covers the site.
4. Submit through the Planning Portal. If something is missing the council writes to you and allows 21 days; it also quotes a £40 charge for householder applications returned before validation (how to apply).
5. Complete a Community Infrastructure Levy form. New floor area above 100 square metres can attract the levy.

The council aims to decide a householder application within eight weeks, and in the year to June 2026 it met that or an agreed extension for 95.0% of them by our calculation from MHCLG counts. If revisions are requested, the council says you get one chance to submit them, and a scheme that ignores the advice can be refused without more rounds.

What if the application is refused?

The council lists three routes: amend and resubmit, appeal within 12 weeks for householder cases, or appeal within six months for other application types (refusal guidance). The Planning Inspectorate's guide gives the same 12 weeks for a householder decision notice (procedural guide). With an 83.2% grant rate, most schemes pass, but a refusal that rests on a specific neighbour impact is often simplest to fix by redesign.

Which questions should you put to a Leeds architect first?

• Do they appear on the Architects Registration Board register? Look them up at arb.org.uk.
• Have they drawn the 45 degree and 12 metre tests onto a Leeds scheme before?
• Will they recommend a paid pre-application enquiry, and what question would it settle?
• Which stages does the fee cover: planning drawings only, or building regulations drawings and site visits as well?
• What happens to the fee if the council refuses?

For the wider picture see the Leeds hub page, the guide to planning permission for an extension and the project pages for Leeds loft conversions and Leeds planning applications.