Two angles and four metres: how Reading judges a scheme
Anything beyond permitted development in Reading is weighed against the council's Design Guide to House Extensions, adopted in March 2021. It is short and fairly blunt.
Start with your neighbour's nearest window to a habitable room. From the middle of that window the guide draws a line at 60 degrees for a single-storey rear addition and 45 degrees for a two-storey one. Stay behind the line and you are on safe ground. Cross it and the council expects to refuse. Ask your designer to draw it on the plans, because the guide wants to see it there.
Depth comes next. The guide says rear additions that go more than 4 metres from the house are unlikely to be supported, single or two storey, though a deeper one can pass if you can justify it. A two-storey scheme also shouldn't bring the back-to-back distance between houses under 20 metres.
Then there's the garden test, which catches people out on tight Victorian plots. Reading wants the usable outdoor space left behind to be no smaller than the floor area of the house. Garages and parking don't count towards it. Small historic gardens are judged case by case, but if your yard is already modest, a full-width addition may leave too little.
One more thing. Reading's guide notes that a north-facing addition usually overshadows next door less than a south-facing one, so the direction your garden faces matters as much as the size.
Matching the build to the house
Roughly in the order they come up on Reading streets. Each links to a longer guide.
Single-storey rear. Off a semi or terrace outside a conservation area, 3 metres is permitted development, 4 on a detached house. Go to a planning application and the council's 60 degree line and 4 metre test take over.
Side return. The passage beside a back wing on a Newtown or Oxford Road terrace is the obvious place to gain width. Infill there counts as a side addition, so on a conservation area street it needs consent.
Kitchen. Most of these projects end with a kitchen. Keep upper and side windows away from next door's garden, since the guide asks for side-facing windows on rear additions to be avoided.
Open plan. Knocking through to a new room means a beam over the old back wall. On the Reading Formation and London Clay in the south-east of the borough, nearby trees affect the footings too.
Wrap-around. Because it goes round the side and the back, both sets of rules apply at once. It usually suits a wider interwar semi better than a narrow terrace.
Two-storey. To the side, Reading wants the front stepped back and the ridge set well below the main roof, with the pair kept symmetrical where possible. Closing the gap to next door is the usual reason these fail.
Home office. An attached room shares the heating and avoids the outbuilding limits, which include a 2.5 metre eaves cap and no raised platform.
Ground-floor bedroom. Fine for a relative. Give it its own kitchen and a separate front door with no link inside, though, and the council may treat it as a new home.
Planning. Before paying for drawings, find out if you are in a conservation area, on an Article 4 terrace or in a flood zone. Neighbours get 21 days to comment on a householder application.
Cost. We don't give a Reading average. Flood-resilient floors, clay footings and a beam through a solid brick wall all move the figure, so compare three quotes on the same drawings.
Floodplain on both rivers, and groundwater in Caversham
The council's 2024 flood risk assessment shows where the risk sits. Along the Thames, much of Lower Caversham is in the floodplain, along with parts of Caversham Heights near The Warren, Portman and Loverock Roads and the streets north of the railway around Cardiff Road and Vastern Road. On the Kennet side there are pockets at Coley and south of Green Park station. In Southcote, homes along Brunel and Hatford Road are partly at risk from the Holy Brook.
If your house is in Flood Zone 2 or 3, a flood risk assessment goes in with the application, and the Environment Agency's standing advice expects raised floors or flood-resilient construction. Caversham has a second issue. The same study says the chalk under Lower Caversham, Emmer Green and Hemdean Bottom can hold high groundwater, which is worth knowing before anyone digs deep foundations.
Where permitted development stops short
In all 15 conservation areas, from Redlands and Christchurch to St Peter's in Caversham, national rules rule out side additions, anything over one storey at the back and new cladding. The bigger 6 or 8 metre neighbour-consultation route isn't available either.
The patterned brick terraces under Article 4 go further. On those house ranges, among them parts of Brisbane Road, Junction Road, Polstead Road and Shaftesbury Road, the council says all permitted development rights are gone, extensions included. Even a modest back kitchen needs an application there.
Where these facts come from
- Reading Borough Council: Design Guide to House Extensions SPD (2021)
- Reading Borough Council: Strategic Flood Risk Assessment Level 1 (November 2024)
- Reading Borough Council: Article 4 directions
- Reading Borough Council: conservation areas and listed buildings
- Reading Borough Local Plan (2019)
- BGS: geology of the Reading district
- Flood risk assessment: standing advice (GOV.UK)
- Permitted development rights for householders, technical guidance (GOV.UK)
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Questions people in Reading ask
Next door's kitchen window is right by our shared wall. How does the 60 degree rule work?
The line starts at the middle of their nearest habitable-room window and runs out at 60 degrees for a single-storey addition. A window close to the boundary leaves you less room, so a shallower or set-in design may be needed. The council expects the line drawn on your plans.
We're in Lower Caversham. Do we need a flood risk assessment for a kitchen extension?
Very likely. The council's flood study puts much of Lower Caversham at risk from the Thames. Check the Environment Agency map, and if you are in Flood Zone 2 or 3, submit an assessment with the application.
Can we use the 6 metre prior approval route on our semi in the Christchurch conservation area?
No. That route isn't open in conservation areas. You can still apply for planning permission, where Reading's guide starts to resist anything deeper than 4 metres unless you can justify it.
Our terrace garden is small. Could the council refuse an extension because of it?
It can. The guide wants usable outdoor space at least equal to the floor area of the house, though older homes with small gardens are looked at individually. A narrower side infill often keeps more of the yard than a full-width build.