Building Regulations are the national standards for how buildings are put up and altered, covering structure, fire, ventilation, energy use and more. They are separate from planning permission, and a job can need one, the other, both or neither. For roofing, the question that matters is whether the work counts as ordinary repair and maintenance, which is mostly left alone, or as a bigger change that has to be checked. This guide covers the position in England. It sets out the tests in plain words so that you know what to expect, but it is not legal advice, and for a definite answer on your own job the people to ask are your local authority's building control team or a registered building control approver.
Planning permission and Building Regulations are different things
Planning permission is about what is built and how it looks and affects the area. Building Regulations are about whether the work, once done, is safe and meets standards. Re-covering a roof in the same style rarely needs planning permission but may need Building Regulations approval, depending on its size. Changing the roof shape or adding a dormer may need both. Our guide to planning permission for roof work covers the planning side, and this page deals with the regulations.
The test for re-roofing: how much is affected
The Planning Portal, which is the government's planning and building guidance service, sets out the test for repairing or re-covering a roof. Its wording is that repair or re-covering work is ordinarily left alone provided it touches under a quarter of the building envelope (the whole outer shell: walls, roof and floor) and under half of the roof itself. Both limits apply together. Go beyond them and approval is required, and the whole roof may then have to be insulated to current standards.
For most houses this means that fixing slipped tiles, renewing a ridge, repairing a valley or replacing a section of flashing needs no application. Stripping and re-covering a whole roof usually does, because it affects more than half of the roof. A common mistake is to treat a full re-roof as a repair. It is not, and the regulations treat it as a renovation of a thermal element. The official page is at Planning Portal: building regulations for re-roofing.
Where common jobs fall
| Job | Usual position |
|---|---|
| Replacing slipped or cracked tiles | Maintenance, no application |
| Renewing a ridge or a verge | Maintenance, but fix to BS 5534:2014 |
| Re-pointing or rebuilding a chimney stack | Usually maintenance, but check for structural changes |
| Stripping and re-covering the whole roof | Over the roof threshold, approval and insulation upgrade |
| Changing slate for heavier tile | Weight test, approval and structural check |
| New or replacement roof window | Thermal and escape standards apply |
| Solid roof on a conservatory | Application needed, load check on frame and foundations |
Treat the table as a guide to the usual outcome. The edge cases are where a conversation with building control earns its keep, for instance a re-roof of one slope of a small house that is close to half the roof, or a partial strip on a roof that has already been repaired in stages.
Insulation: the roof is a thermal element
When a roof covering is renewed over a large enough area, the roof is treated as a thermal element, meaning part of the building's heat-loss surface, and Approved Document L (conservation of fuel and power) applies. In practice that means that a re-roof can bring a requirement to bring the insulation up to a modern standard. In a cold loft this is often done by adding insulation at ceiling level when the roof is open, and in a warm roof it is built into the new construction. Flat roofs follow the same logic: stripping a membrane and laying a new one, as opposed to overlaying the old, tends to pull the insulation upgrade into the scope of the work. Our pages on roof replacement and Building Regulations and flat roof Building Regulations go through how this works in practice.
A heavier covering needs checking
Where the new material weighs 15% or more above what it replaces, the job needs approval and the roof structure may have to be strengthened. That comes from Approved Document A, the part dealing with structural safety. It is most likely to matter when concrete tiles replace slate or lightweight sheet, or when natural stone replaces concrete. A roof built for slate carries less than one built for heavy tile, and the rafters, purlins and walls have to be shown to cope. It matters on flat roofs too, if paving, decking or planting is added. Our page on how heavy roof tiles are explains the weights, and we check the existing structure before suggesting a change of covering.
Roof windows and rooflights
New or replacement roof windows in existing homes must meet energy standards. The Part L 2021 table for existing dwellings sets the figure for a roof window at 1.4 W/m²K, or Window Energy Rating Band B, and for a rooflight at 2.2 W/m²K. A new roof window can also affect means of escape. Under Approved Document B, a roof window only counts as an escape window for storeys within 4.5 metres of the ground, and a loft conversion on a two-storey house needs a protected stair, not a roof window. These rules and the planning side are covered in our roof windows hub, and the page on roof window Building Regulations sets them out in full.
Solid roofs on conservatories
Replacing a translucent conservatory roof with a solid one needs a Building Regulations application. The reason is load: the frame and foundations were designed for a light roof, and building control checks that they can take the extra weight. A pre-approved roof system can make approval quicker, yet the application itself is still required. Our guide to conservatory roof Building Regulations covers it.
Spray foam and other insulation work
Insulation applied to the underside of a roof is part of the thermal performance of the building, and it can change how the roof handles moisture. RICS advice to consumers on this material points out that foam can hold moisture against the timbers and leave the roof hard to inspect. The regulations side, and the knock-on for sale and mortgage, is covered in spray foam and Building Regulations.
Ridge, hip and verge fixing
The British Standard for fixing clay and concrete tiles, BS 5534:2014, requires mechanical fixing of ridge, hip and verge components, so mortar alone is not relied upon. A second standard, BS 8612:2018, deals with the dry-fix kits themselves. This is not a Building Regulations application in the sense above, but it is the standard that good work follows, and it is why a ridge that was bedded in mortar decades ago is often renewed with a dry-fix system. Our page on mechanical fixing of ridge tiles explains it.
Asbestos, and why it sits outside this
Asbestos cement roof sheets are a health and safety matter before they are a building matter. The Health and Safety Executive treats careful removal of whole sheets as non-licensed work that still needs a risk assessment, controls and trained workers, and it becomes notifiable if the material will be substantially broken up. If your garage or outbuilding has an old cement sheet roof, our guide to asbestos garage roof removal explains what applies.
Listed buildings, conservation areas and wildlife
Like-for-like repairs on listed buildings and in conservation areas are usually fine, but changes to the material or appearance of a roof may need consent. That is separate from Building Regulations, and the council's conservation officer is the person to ask. Birds that are nesting and any bats in the roof are protected, which can mean waiting or having a survey done before work begins.
What approval involves in practice
An application is made before work starts, with drawings or a description of the roof structure, the proposed covering and the insulation. Building control may ask for calculations if the covering is heavier or the structure has changed. Inspections happen at set stages, typically when the old covering is off and the structure is visible, and again when insulation is in. When the work is finished and passed, the body issues a completion certificate. Skipping the early inspection is the usual reason an application becomes awkward, because once the new roof is on, the structure is hidden. If you are doing a larger job, ask your roofer when the inspections will happen and who books them.
Who decides, and what happens in practice
If your work is notifiable, you have two routes. You can apply to your local authority's building control team, or use a registered building control approver, the private-sector option that took that name in April 2024. Either will inspect the work and issue a completion certificate. A reputable roofer should tell you at the quote stage whether the job needs approval, and who makes the application. Keep the certificate. It is the paper a buyer's solicitor will ask for, and its absence can hold up a sale. Our guide to buying a house in Basingstoke: the roof checks explains why.
Why the rules exist
Each test answers a real risk. The coverage threshold reflects the point at which a roof job stops being patching and becomes a rebuild of the heat-loss surface. The weight test exists because a roof structure sized for one covering can sag or spread under another. The window rules protect people from heat loss and from being trapped upstairs in a fire. The conservatory rule protects the frame. Seen this way, the regulations are less a hurdle than a checklist of the things a careful roofer would want to be sure of anyway, and most of what building control asks for is what a careful survey has already established.
Commercial buildings
The same principles apply to commercial roofs, though the energy rules for non-domestic buildings sit in a different volume of Approved Document L. Our page on commercial roofing and Building Regulations sets out how that works.
What we do
When we quote, we say whether we think your job is notifiable and, if it is, we take the application on. Whenever the work does need approval, the application falls to us, and the paperwork is part of the price, not an extra that surprises you later. The survey is free and photographed, the quote is fixed, and the finished roof has a guarantee that lasts a decade. If you are not sure whether your plans are near the threshold, start with the homepage or ring 01256 213956 and describe the job.
