Do heavier roof tiles need Building Regulations approval?

Putting a heavy covering on a roof built for a light one loads the rafters and walls harder. The Planning Portal's re-roofing guidance tells you to obtain approval when the replacement covering adds at least 15 per cent to what the old one weighed. Approved Document A, which deals with structure, words it a little differently: it calls an increase of more than 15% a significant change in roof loading, and the strengthening that results counts as a material alteration. The roof structure was designed around whatever covering it originally carried, not around one you might pick later. If you are unsure what is on the roof now, the maker's name on the underside of a tile, or a sample taken to a merchant, will help identify it.

The two wordings part company at exactly 15, so the safe course is to treat roughly 15% heavier as the line and ask building control. Any swap between coverings of different weight can cross it, so compare the data sheets first. Going lighter does not raise the load, though the Planning Portal asks for a check wherever the new tile is much heavier or much lighter than the old one.

Weight is not the only test. On the Planning Portal's thresholds, no building control application is normally required while less than 25 per cent of the total building envelope is affected and less than 50 per cent of the roof. Both limits must hold, so a small repair is in a different position from a full strip and re-lay. Your roofer should know which applies before the scaffold goes up. Approval is also needed for structural alterations, and where the new covering would perform noticeably differently from the old if fire reached it.

Arun District Council's building control page puts the replacement of pitched and flat roof coverings on its list of works needing approval, and invites you to check your own case with its team. Those two positions sit together: the national guide sets thresholds, and the council tells you how they apply to your house. Where a roof is renovated heavily, thermal upgrades under Part L can apply as well, covered in our guide to underlay and ventilation.

A building control application goes either to the council's own team or to a registered building control approver. The registration regime for approvers has applied since April 2024, though private building control existed before then. Inside the South Downs National Park, building control stays with the district council even where the National Park Authority decides planning.

Where the work is notifiable, we talk you through consent and submit the Building Regulations notification ourselves. The completion inspection is arranged with whichever body holds the application, and Arun asks for a day's notice before it inspects. The council or approver may ask for the data sheet of the new tile, so keep it with the job papers. Keep the completion certificate safe too. A buyer's solicitor often asks for it, and a missing one can be awkward to replace years later. Clay and concrete tiles differ in weight from product to product, so each case needs its own data sheets.

Weight and approval do not decide whether planning permission is needed. Replacing a roof like for like generally leaves the building's outward look unchanged, so it falls outside what the Town and Country Planning Act counts as development. Changing the look, such as going from slate to concrete, is another matter in some places, and listed buildings and Article 4 areas bring their own rules.

If the house is in a conservation area, in the National Park or in Chichester Harbour National Landscape, ask the planning authority before changing the material. Our guide to pitched roof planning permission goes through who decides, and the answer on changing tiles in a conservation area covers local cases. Treat weight and appearance as two separate checks, each with its own answer.

Find the weight of the old covering and of the new one, per square metre, from the makers' data sheets. Work out whether the difference reaches 15 per cent. If the roof already looks tired, bring in a structural engineer or surveyor, as the Planning Portal advises before work begins where the tile is significantly heavier or lighter.

Then have your roofer set down, in writing, whether building control is involved, who applies, and who collects the completion certificate. Ask what happens if the inspector wants the roof strengthened, because that changes the job and the sum. A price that skips this is incomplete. Ours states the answer, and arrives after the survey as one sum. The pitched roofing page shows how a re-roof runs from survey to clear-up, with waste taken away at the end.