Replacing a roof sounds like maintenance, and much of it is. But several sets of rules can reach a roofing job, and they do not all ask the same question. Building Regulations look at safety, energy and how much of the building is being altered. Planning law looks at how the outside of the house changes. Listed building and conservation rules look at the character of the building and its street. Highway law looks at where the scaffold stands.
Plenty of repairs and like-for-like re-roofs pass through all of this without any application. The skill is in knowing which jobs do not, so that you ask the right body before work starts rather than after. This guide is an overview, not legal advice. It sets out the main tests in plain words, names who to ask in Crawley and the councils around it, and points to the pages on this site that go deeper. Where a national test and a local council's own wording differ, both are shown, with a note of which is which.
Building Regulations: when roof work needs approval
Building Regulations reach roof work in England. Sign-off turns on two questions: how big a share of the house the job disturbs, and which covering finally goes on top.
What is the national test?
Planning Portal guidance sets two ceilings for skipping building control approval: under 25 per cent of the building envelope, and under 50 per cent of the roof itself. The envelope is the walls, floor, roof, windows, doors, roof windows and roof-lights added together, and both limits have to hold. Read the full wording on the Planning Portal roof page.
What triggers approval whatever the area?
Two things. Added load is the first trigger, and the Planning Portal sets it at 15 per cent or more over the existing covering. Fire behaviour is the second: if the new material would react to flames noticeably differently from the old, approval is needed again. A light slate swapped for a heavy concrete tile is the textbook case, because the rafters were sized for the old load. When the weight is open to doubt, the Planning Portal tells you to get a structural engineer or surveyor involved before the work starts.
What does Crawley say?
Crawley Building Control states that repairing or replacing more than 25% of a roof's surface area needs its approval. That wording differs from the national test, and it applies to houses in the borough. We follow it, and on a large re-roof we contact the team before work begins. Elsewhere, ask the council's own building control team which test it uses, and ask for the answer by email. Our post on planning permission for roof work covers the next layer.
Energy rules for roofs: Part L
Part L of the Building Regulations deals with saving fuel and power, and it shapes what goes into a roof when the roof is renewed. A new covering is often the moment insulation has to be looked at, so it affects the quote as well as the build.
When does a roof count as renovation?
Approved Document L, Volume 1 for dwellings, in its 2021 edition, took effect on 15 June 2022. Under it, a flat roof given fresh waterproofing counts as renovated. Renovating over a quarter of the external envelope makes a major renovation. Separately, when over half of one element, such as the roof, is renovated, that element must be brought up to standard.
Which U-values apply?
Read these figures as a guide to what the inspector will ask for. Table 4.2 covers new or replacement elements in an existing dwelling: roof 0.15 W/(m²·K), windows 1.4 or Window Energy Rating Band B at the least, rooflights 2.2. Table 4.3 covers renovating an existing element, with a threshold of 0.35 for the roof and an improved value of 0.16. Where that target is impractical, or would take over 15 years to repay its cost in saved energy, the upgrade falls back to the best value that is practical and pays for itself within 15 years.
Is a new edition coming?
Yes. The 2026 edition applies from 24 March 2027 to building work other than higher-risk building work. Its tables are renumbered 3.2 and 3.3 and the payback paragraph becomes 3.14. Until then the 2021 tables rule. Ask your building control body which edition your job falls under. Our roof replacement page explains how insulation fits into a quote.
Who deals with building control around Crawley
Which body checks the work depends on the council area, and it is not always the council whose tax you pay. Knowing the name before the job starts saves a week of phone calls.
How does it work in Crawley?
Crawley Building Control, the council's Local Authority Building Control service, handles all building control work in the borough. Its contact details are on the Crawley Borough Council website, and anyone planning a larger re-roof should be in touch with it before the job begins, not after the tiles are on.
What about the councils nearby?
Horsham District Council trades as Sussex Building Control. Mid Sussex District Council runs its own service. Southern Building Control Partnership is the team for Reigate and Banstead, Tandridge and Mole Valley. Wealden belongs to the East Sussex Building Control Partnership alongside Eastbourne, Hastings and Rother. Guildford has its own service, and Epsom and Ewell is managed by Elmbridge Building Control Services. For any other council, ask its building control team who deals with your address.
Can a private approver do it instead?
Yes. Since 6 April 2024 private approvers have had to be registered, and government guidance says one that breaks the professional conduct rules can be sanctioned. Private building control existed before that, so only the registration is new. Inside the South Downs National Park the park authority decides planning in some council areas, but building control stays with the district council. Our areas we cover index shows the councils for every town we work in.
Planning permission, listed buildings and conservation areas
Planning is about the outside of the building. A like-for-like covering normally changes nothing you can see, and section 55 of the Town and Country Planning Act 1990 says that a job leaving a building's exterior materially unchanged falls outside the definition of development.
What changes with roof windows and dormers?
Class C of the permitted development order is the catch-all for other roof alterations to a house. It does not cover an alteration that sticks out more than 0.15 metres from the original slope, that lifts the highest part of the roof, or that involves chimneys, flues or solar equipment. A window in a side slope has to be obscure-glazed, and fixed shut unless its opening parts sit more than 1.7 metres above the floor. Dormers fall under Class B, with volume limits of 40 cubic metres on a terrace house and 50 on any other house, and it does not apply on article 2(3) land such as a conservation area, a National Park or a National Landscape.
What about listed buildings and conservation areas?
A listed house keeps its Class B and Class C rights but also needs listed building consent for alterations that would alter its character. Conservation areas bring extra controls, and an Article 4 direction can withdraw permitted development rights across a defined area. Phone the council's planners and give your full address before you commit to anything. See our pages on re-roofing a listed building and re-roofing in a conservation area.
Scaffold licences, party walls and wildlife
Some consents have little to do with the roof covering and everything to do with where the work happens or what lives under it.
When does a scaffold need a licence?
Section 169 of the Highways Act 1980 bars anyone from putting up or keeping scaffolding that obstructs the highway without the highway authority's licence. Scaffolding sited entirely on private land needs no licence. West Sussex County Council wants 10 working days' notice and lists a month of scaffolding at £266, and Surrey County Council charges £208 for each 28 day period. In Kent, the county council asks the scaffolding firm to put in the application on the customer's behalf. Elsewhere, put the question to your roofer and get the answer in writing, because the rules are not the same in every county. See scaffolding for roof repairs.
What about shared walls?
Work on a roof that meets a neighbour's wall, or on a chimney shared between houses, can raise party wall questions. Our answer on the Party Wall Act and roof work explains when to ask, and a party wall surveyor can advise on your own case.
Do bats and birds matter?
They do. Government advice says bats are fully protected, along with the sites where they breed or rest, and names roof repairs and re-roofs among activities that may disturb them. Nesting birds are covered as well: wrecking a nest on purpose while the birds are building or using it breaks the law. Mention any sign of bats or nesting birds before work starts, so a plan can be made around them.
Where to look next, and what to ask
The rules above set out the main tests, and the detail lives in the guides that follow. Use this section as a checklist.
Which guide covers which question?
For costs, our roof work costs guide shows national ranges with their sources. For lifting equipment near the airport, see cranes and tall equipment near Gatwick. For choosing a firm, read how to tell a dodgy roofer. Planning questions on dormers, roof windows and extensions sit in the post linked in the first section above, and the pages on listed buildings and conservation areas cover the special cases.
What should you ask a roofer?
Ask whether the job covers a big share of the roof, whether the new covering is heavier than the old, and whether the address is a listed building or sits inside a conservation area. Ask who tells building control, who applies for any scaffold licence, and whether anything in the loft suggests bats or nests. Ask that each answer is noted in the written quote, so nothing depends on memory. Keep a copy of every email and any council reference number, because they settle arguments faster than recollection does.
What happens at our survey?
We begin with a survey and show you pictures of your own roof. At that visit we check your address against the points above, and the written total is given afterwards, so it reflects what has to be done. If a council has to say yes to something, you hear at that stage, not on the day the scaffold arrives. Our home page describes how a job runs.
Part of Roofers in Crawley: the full guide
Roof rules at a glance
Does re-roofing need planning permission?
Usually not for a like-for-like covering, because planning law ignores jobs that leave the exterior of a building materially as it was. Roof windows and dormers are another matter, and listed buildings and conservation areas have extra rules. Ask your council's planning team about your address.
Do I need building control approval for a new roof?
Possibly. Per national guidance, approval is not usually required where the work touches under 25 per cent of the envelope and under 50 per cent of the roof, although a heavier covering can trigger it. In Crawley, Crawley Building Control applies its own wording to larger re-roofs, so ask them.
Who applies for the scaffold licence?
It depends on the highway authority. Kent County Council says the scaffolders should be the ones to apply for you. In West Sussex, Surrey and other areas, ask your roofer who applies, because the answer is not the same everywhere. No licence is needed if the scaffold stands wholly on private land.
