Planning permission for additional storeys
Extending upwards to add a storey can be permitted development, but it runs through a prior-approval application and only applies to certain houses built between 1948 and 2018.
Adding a storey is a way to gain a whole floor without extending the footprint. Since 2020 there is a permitted development route for it, but the eligibility rules are narrow and a prior-approval application is always required.
- One extra storey on a single-storey house, or up to two storeys on a house of two or more storeys
- Overall height not exceeding 18m, and each new storey no more than 3.5m high
- House built between 1 July 1948 and 28 October 2018, with no storeys previously added
- A prior-approval application to the council covering impact, appearance and amenity
- Flats and buildings containing flats, and homes on designated land or an SSSI
- Houses converted to residential use under permitted development
- Schemes that exceed the height limits or add more storeys than allowed
- Any case where the council refuses prior approval, a full application is then needed
Don't forget building regs
A new storey is a major structural change: the existing foundations, walls and floors must be checked to carry the extra load. Building regulations approval and structural calculations are always required, and our structural engineers handle both.
This is a route where the eligibility detail matters. We confirm your home qualifies, prepare the prior-approval application, and, because we have structural engineers in-house, verify the existing structure can take another floor before you commit. Talk to us via the contact page.
Frequently asked
Can I add a storey to my house without full planning permission?
Potentially. A permitted development route allows one or two extra storeys through a prior-approval application, but only for houses built between 1948 and 2018 that are not flats, not on designated land, and have not already been extended upwards. We confirm eligibility before anything else.
How tall can the house be after adding a storey?
The finished house cannot exceed 18m overall, and each added storey is limited to 3.5m. On attached houses it also cannot rise more than 3.5m above the neighbouring property. We design within these limits.
Not sure where your project stands?
Checking whether you need planning permission is one of the first things we do: on the house, before any drawings. Tell us about your project and we'll confirm the route.