Question answered
Building Regulations when changing a stone roof
The short answer
Converting a single lap stone roof to double lap calls for the loading and structural stability to be reviewed, and for building control approval, or a church faculty where one applies. The Stone Roofing Association says so directly. Other changes, such as a heavier covering, can also need approval, so ask your building control body before work starts.
Relaying a stone roof as it was needs little paperwork. Changing how it is laid, or what covers it, can bring Building Regulations into play and a structural check with them.
Changing lap: what the Stone Roofing Association says
The Association prefers that double lap slating is kept or put back wherever possible. Where a single lap roof is to be converted, it says someone must look again at the load the roof puts on the building and at its stability, and that building control approval will be needed, or a church faculty for a church.
The reason lies in the stone. Altering the lap changes how many layers of slate sit over each part of the roof, so the load on the timbers changes with it. The frame was built for the roof as it stood.
If the proposals affect a listed building, the Association adds that listed building consent from the local authority will be needed as well. Single lap Horsham stone explains the two systems first, and Horsham stone roofing shows the repairs that normally follow.
When re-covering reaches the thresholds
The Planning Portal's test has two parts. Building control is not normally involved in a repair or re-covering that touches less than 25 per cent of the total building envelope and less than 50 per cent of the roof. Go beyond one of them and approval is needed.
The Portal names other triggers: structural alterations, a covering that would behave very differently in a fire, and any new covering that adds 15 per cent or more to the weight carried. Approved Document A phrases the weight point differently, calling an increase of more than 15% a significant change in loading, so quote whichever source you are working from.
Stone is heavy, so swapping it for a lighter material may not trip the weight rule, yet the Portal still points to checks on weight whenever the replacement differs markedly from the old covering, in either direction. Our page on Horsham stone or clay peg tiles works through that choice in detail.
Repairs that stay outside the rules
Replacing a few broken slabs, resetting slipped ones and renewing a short run of ridge are repairs. They sit well under the limits above and do not usually call for an application, provided the covering, the pitch and the structure stay as they were.
The test is scale and change. Relaying the whole roof in its own stone, in the same lap, is a repair in spirit though a large one, and it is sensible to check the thresholds with building control first. Replacing one stone slate shows the small end of the scale.
On a listed roof, building control and listed building consent are different permissions. Passing one does not satisfy the other, so ask both bodies and keep both answers in writing with the house papers.
Thermal upgrade and fire performance
Part L can follow a larger re-roof. Approved Document L treats a strip to the bare structure and rebuild as renovating a thermal element. The whole element then has to be improved if more than 50% of its surface is renovated, and a major renovation is defined as work to more than 25% of the external envelope. A roof that is relaid slab for slab in its own stone may still reach those figures on a small house, so the arithmetic is worth doing early.
A historic stone roof raises its own questions about how far insulation can go without harming the building, and a conservation officer or building control may have a view. Raise it early, before the stone is off.
The Planning Portal also says approval can be needed when the new covering will perform significantly differently in a fire. Stone behaves differently from some modern coverings, so ask your building control body rather than assuming either way.
Which office to contact
In Adur and Worthing, the councils run a single building control team from Worthing Town Hall. Elsewhere it is your district council, or a registered building control approver, which is the term used since 6 April 2024. In the National Park the planning authority is the SDNPA, but building control is a separate question.
Bring photographs of the existing roof, a short note of the plan and, where the structure is in doubt, an engineer's report. How long stone roof repairs take gives the order of events. Where the work is notifiable we explain the consent position and handle the Building Regulations notification for you.
For the lime finish beneath the slates, see torching under stone slates. Once the roof is surveyed you get the written quote, with the price as one figure. Councils can take time to respond, so allow for that when you plan the start date, and ask the building control team how its inspection stages are booked, because the owner may have to inform them as work reaches certain points.
Stone roof paperwork, two further points
Is approval needed to relay my stone roof in the same pattern?
A like-for-like relay is unlikely to alter the loading, but its scale may still reach the Planning Portal thresholds, so check with building control before starting. A change of lap is different: the Stone Roofing Association says it needs a loading review and approval from the start.
Does listed building consent replace Building Regulations approval?
No. They are separate. Listed building consent concerns the character of the building, while Building Regulations concern structure, safety and performance. A listed stone roof may need both, so ask each body and keep both approvals with the house papers.
Tell us about your roof
Describe what is happening and we will call you back to arrange a visit.
- Photographs of what we find
- A written quote with one total price
- Or call 01903 299063
10-year workmanship guarantee, in writing.