Check the decade your neighbourhood was built
Most of Crawley was built to a plan, and quickly. The town became a New Town in January 1947. Within about ten years the Development Corporation had filled West Green, Northgate, Three Bridges, Langley Green, Ifield, Tilgate and the southern half of Pound Hill. Gossops Green and Furnace Green came next, Broadfield and Bewbush in the 1970s, then Maidenbower, planned in 1986 as a privately built neighbourhood. Forge Wood is the newest of the fourteen.
That timetable matters up in the roof. The 1950s houses are mostly terraces and semi-detached pairs in pale red brick under pitched tiled roofs. The county history of the town notes that "in the 1960s roofs of lower pitch were adopted". So a 1950s terrace in Langley Green or Northgate can have more height to play with than a house of similar size in Furnace Green, where building started in 1961. Later estates are more likely to have trussed roofs, which can still be converted, but the trusses come out and steel goes in. Get the height measured before you pay for drawings.
Why convert at all? At the 2011 Census, 41.8% of Crawley's homes were terraced and only 13.9% detached. Nearly half had three bedrooms, and just 15% had four or more. A loft is the usual way to get that fourth bedroom without leaving the street.
Here is how each type tends to suit Crawley's houses.
Rear dormer. The standard answer for a New Town terrace, and normally permitted development outside a conservation area. One local quirk: many houses were set at angles or grouped round courts, so the back of yours may face a road or footpath. Check which slope counts as the front before you assume.
Extra bedroom. This is what most Crawley conversions are for, turning a three-bed into a four-bed. Building control looks hard at the new stair and the fire protection before it signs off. Make sure both are priced in the quote.
Hip to gable. For semis and end-of-terrace houses with a sloping end roof. On the lower 1960s pitches, squaring off the end adds floor area but may not fix headroom on its own, so it is often paired with a rear dormer.
Read our full guide: Hip-to-Gable Loft Conversions: What It Involves and Which Houses It Suits →
Rooflights only. Only works where the roof is already tall enough, which in Crawley usually means the 1950s stock or older. On Hazelwick Road the conservation area statement asks for flush-fitted rooflights, with no upstands or blind boxes.
En-suite. Decide early. Where the soil pipe can run sets where the shower goes, and in a terrace you have no side wall to play with.
Home office. The top of the house is the quietest room you have. Ask for a data cable to be run up while the walls are open, because it is a nuisance to add later.
Read our full guide: Loft Home-Office Conversion: What Works Well Up There and What to Specify →
L-shaped dormer. Needs a two-storey back addition with its own roof to build over. If your house has one, a second dormer there usually takes the bathroom.
Mansard. Almost always a planning application. When the council proposed two new conservation areas in 2022, it named poor quality upward extensions as one of its worries, so expect a mansard to be looked at closely.
Planning. None of Crawley's 19 Article 4 directions touches roofs. They cover HMOs on ten small streets, offices on the business parks and one site's fences. What can take away permitted development here is a conservation area, a listed building, or a condition on your estate's original consent. The council's Householder Development SPD, adopted in June 2026, sets out what it expects when you do apply.
Cost. We don't print a price for Crawley. A low trussed roof and a tall 1950s one are different jobs, and a web page figure would mislead you. Three site visits will.
Older streets south of the railway
Before the New Town there was a village on the London to Brighton road. The railway arrived in 1841 with a station at Three Bridges, a Horsham branch followed in 1848, and the town spread south around the new station. West Street, Springfield Road, Perryfield Road and Malthouse Road all come from that growth. The old High Street sits on sandstone. The Victorian streets were built on Weald Clay.
Two of these areas are now protected. Hazelwick Road in Three Bridges was built out between 1895 and 1906, with terraced railway cottages and villa-style semis at the North Road end, in local stock brick, mostly under plain clay tiles. Malthouse Road in Southgate has large Edwardian semis. In both, roof alterations need planning permission. Some Hazelwick Road semis have already gone up to two and a half storeys, which shows a careful scheme can get through.
Forestfield and Shrublands
Crawley does something few towns do and protects parts of its post-war housing. Forestfield and Shrublands, two Furnace Green estates of the late 1960s and early 1970s next to Tilgate Park, became a conservation area in 1996. What counts there is the estate as a whole, down to the green space between houses and the paths kept apart from the roads. It has its own advisory committee that comments on applications. A dormer nobody would notice in Bewbush will be judged against the estate here, so use the council's pre-application advice before anything is drawn.
Building control changed hands in 2025
From 2006, building control in the borough was run by Sussex Building Control, based at Horsham District Council. Since 23 October 2025 Crawley has done it itself, as Crawley Building Control. Applications go through its own portal, and the team's email is building.control@crawley.gov.uk. Inspectors visit at stages and issue a completion certificate at the end. Keep it with the deeds. A buyer's solicitor will want it.
Where these facts come from
- Crawley Borough Council: conservation areas
- Crawley Borough Council: Forestfield and Shrublands
- Hazelwick Road Conservation Area Statement (2019)
- Crawley Borough Council: Article 4 directions
- Crawley Borough Council: new building control service (2025)
- Crawley Borough Council: water neutrality
- Crawley Historic Character Assessment (2008)
- Victoria County History: Crawley New Town
- Northern West Sussex SHMA 2019 (2011 Census housing mix)
How FirQuote works in Crawley: We connect you with local specialists who visit your property before giving you a price. You get up to 3 written quotes — no call centres, no estimates from photos, no obligation to accept any quote.
Questions people in Crawley ask
We're in a 1960s house in Furnace Green. Is the roof too low to convert?
Not necessarily. Houses there started going up in 1961, around when the town moved to lower roof pitches, so headroom is the first thing to measure. A rear dormer often solves it. If you are inside Forestfield or Shrublands, the conservation area adds a planning application to the job.
Is water neutrality still holding up applications in Crawley?
No. Natural England's Sussex North position statement of September 2021 stalled many applications, and householder decisions only restarted in December 2021, with annexes and swimming pools still held back. Natural England withdrew the statement on 31 October 2025. An ordinary loft conversion no longer has to show anything on water.
Our old building control paperwork says Horsham. Is that right?
Yes. Sussex Building Control, based at Horsham District Council, handled Crawley's building control from 2006 until October 2025. A completion certificate from them is valid. New work now goes to Crawley Building Control.
How do I find out if my street is in a conservation area?
The council lists all 13 on its conservation areas page, from the High Street and Ifield Village to Hazelwick Road, Malthouse Road and Worth. Then search your road on the planning register to see what neighbours have been allowed to build. That is the best guide to what will pass.