A loft conversion turns unused roof space into a habitable room such as a bedroom, bathroom or office, with a proper staircase, insulation, fire protection and natural light from rooflights or a dormer.
Addresses across SL4 fall within our coverage for a loft conversion, so if your home is in Windsor we can arrange a survey on a day that works for you. We inspect the existing building, discuss materials and layout, and then price the agreed specification in writing. Expect a guide range of £33,500–£73,000 including VAT before that visit.
- Guide price
- £33,500–£73,000 inc VAT
- Time on site
- 6–10 weeks on site
- Postcodes
- SL4
- Planning rules
- England
- Local area
- Windsor and Maidenhead
- Survey
- Free, with a written quote
Loft conversions prices in Windsor
Every figure below is a guide for a loft conversion in Windsor, inclusive of VAT. Regional pricing for the South East works out about 12% above the national guide, and the overall span is £33,500–£73,000. The survey costs you nothing, and after it we commit to a firm price for your specification in writing.
| Type of job | What it usually involves | Guide in Windsor |
|---|---|---|
| Rooflight conversion | Rooflights in the existing slope, a new floor, staircase and insulation, where head height already works. | £22,500–£39,000 |
| Dormer conversion | A rear dormer adding headroom and floor space, often with a bedroom and shower room. | £36,000–£67,000 |
| Hip-to-gable or mansard | Larger structural changes to the roof for the maximum usable space. | £56,000–£95,000 |
What moves the price up or down:
- Floor area, existing head height and roof structure
- Steelwork and any strengthening of walls below
- Adding a shower room or en-suite in the roof
- Staircase layout, fire doors and the level of finishes
What do you get?
- Structural calculations and steel beams where needed
- New floor joists strong enough for a habitable room
- Staircase designed to fit your landing and meet regulations
- Insulation to walls, roof slope and floor
- Fire doors, mains-linked smoke alarms and a protected escape route
- Electrics, heating and plumbing by qualified trades, with certificates
Homes in Berkshire
Reading's Victorian terraces often show the town's patterned red and silver-grey brickwork, while Windsor, Maidenhead and Newbury mix Georgian, Victorian and Edwardian houses. Bracknell grew as a post-war new town with planned estates, Slough has a great deal of interwar and post-war housing, and newer developments sit on the edge of most towns.
Much of the Thames Valley is low-lying, so flood risk and clay ground near the river can influence foundations and drainage for extensions.
So when we survey a Windsor property for a loft conversion, the first step is working out how it was built and what has been changed since.
Permissions for a loft conversion in Windsor
Homes in Windsor come under the regulations for England, summarised below. We don't rely on general rules alone: we confirm the position for your address with the council before a quote goes out.
In England, many loft conversions are permitted development: up to 40 m³ of extra roof space on a terraced house and 50 m³ on a semi-detached or detached house, no dormer on the front roof slope facing a road, nothing higher than the existing roof, and similar-looking materials. Conservation areas, listed buildings and flats need planning permission.
Building Regulations approval is always needed for a loft conversion: floor strength, a proper staircase, insulation, fire-protected escape route and smoke alarms. The Party Wall etc. Act 1996 usually applies on attached houses.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
The four stages
Survey and measure
Book a visit and we'll come to you. The survey covers measurements, the state of what's there now and any obvious constraints, so the price that follows is based on your actual home, not an average.
Written quote
You get the price in writing, itemised so you can see where the money goes. As long as the specification stays the same, that is the price you pay for a loft conversion.
Booking the work
Next comes planning the work itself. We set a start date that suits you, line up the right trades, and make sure any approvals for a loft conversion are in place before the first day on site.
Finish and handover
On site, the agreed plan is followed and any change is put in writing first. At completion we do a final clean, go through the snagging list with you and leave you with the relevant documents.
Why homeowners choose us
Loft conversions in Windsor: questions
Which postcodes in Windsor do you cover?
We cover SL4, along with the rest of Berkshire. If your postcode is not listed, get in touch anyway: our coverage is UK-wide, and we can usually arrange a survey wherever you live. Enter your postcode in the guide-price tool or contact form and we will confirm.
Do you cover Slough, Egham and Staines?
Yes. As well as Windsor, we cover Slough, Egham and Staines and the rest of Berkshire. Our coverage is UK-wide, so the process is the same wherever you are: a free site survey, a quote in writing that fixes the price for the agreed scope, and one point of contact while the work is planned and carried out.
Where will the new staircase go?
The new staircase usually sits above the existing stairs, rising from the landing so it uses space that is already circulation. Sometimes it needs to come from a small bedroom or box room, which reduces that room's size. Building regulations set rules on headroom, step size and handrails, with some flexibility for lofts. We look at options at the survey and show you how each affects the floor below.
Does the Party Wall Act apply to a loft conversion?
The Party Wall etc. Act 1996 applies in England and Wales only, and loft conversions on terraced and semi-detached houses often fall within it, because steel beams are usually set into the shared wall. You must serve notice on the neighbour before work starts, and they can agree or appoint a surveyor. Scotland and Northern Ireland have no equivalent Act. We tell you during the survey whether notices are likely.
Do I need planning permission for a loft conversion?
Whether a loft conversion needs planning permission depends on its size and design, your home's location, whether it is listed or in a conservation area, and which UK nation you live in. In England, many conversions fall under permitted development if the added volume is within 40m³ for terraced houses or 50m³ for other houses and nothing extends beyond the front roof slope. We check what applies before quoting.
Near Windsor
We survey and quote throughout Windsor's SL4 postcodes and in surrounding places such as Slough, Egham and Staines. The process and pricing approach are identical in each of them.