Covering Harrow
Harrow sits 10 miles north-west of London, with Brent 2 miles to the south-east and Wembley 2 miles to the south-east.
Homes in London
Much of London’s housing is Victorian and Edwardian terraces, which is why side return extensions, rear dormers and mansards are so common. Many streets are in conservation areas, and several boroughs use Article 4 directions that remove some permitted development rights.
What goes into an upward extension?
The first question is whether the existing walls and foundations can carry the extra load, so we start with a structural survey. Then we design either a full first floor or a raised roof with dormers, handle planning or prior approval, and build the new storey while protecting the floor below.
- Design and planning or prior approval application
- Roof removal and temporary weather protection
- Staircase and changes to the ground floor layout
How much should I budget for an upward extension?
What bungalow and upward extensions typically cost. These are guide ranges; the written quote for your house replaces them.
| Bungalow and upward extensions | Guide price incl. VAT |
|---|---|
| Chalet conversion with dormers (total) | £45,000 to £85,000 |
| New first floor, standard specification | £2,200 to £2,800 per m² |
| New first floor, good specification | £2,800 to £3,300 per m² |
| New first floor, high specification | £3,300 to £3,800 per m² |
What approvals does an upward extension need in England?
English projects need planning clearance from the local council, building regulations sign-off from building control, and party wall notices where the work is on or near a shared boundary. We prepare and manage all three.
In England, Class AA permitted development allows an extra storey on many detached and semi-detached houses built between July 1948 and October 2018, subject to a prior approval application covering design, neighbours’ amenity and other matters. Houses in conservation areas and other protected land need full planning permission, as do most chalet conversions with front dormers.
What can affect an upward extension?
- The staircase takes space from the ground floor plan.
- The house is exposed while the roof is off, so the sequence is planned tightly.
What happens after I enquire?
- Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
- Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
- Price and paperwork. The design is priced line by line, and we submit the planning and building control applications.
- We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.
What people ask before starting
Is an upward extension permitted development?
In England, Class AA allows it on many post-1948 houses through a prior approval application. Elsewhere planning permission is needed.
Do we need to move out?
Often for part of the job, while the roof is off and the new floor is formed. We plan this with you.
Can you visit a house in Harrow to quote?
Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.
Other towns nearby
- Bungalow and upward extensions in Brent
- Bungalow and upward extensions in Wembley
- Bungalow and upward extensions in Northolt
- Bungalow and upward extensions in Greenford
Learn more about bungalow and upward extensions, or see every project we cover in Harrow.