The short answer
No. No law demands dry fix, and nobody has outlawed mortar. BS 5534, the code that guides roof tiling, is a standard rather than an Act, and Marley notes that working to it is not demanded by law. The standard does say a ridge held by mortar alone is not enough, so new work is expected to carry mechanical fixings.
Nobody is breaking the law by keeping a mortar ridge. The standard that roofers follow has still moved on, and good practice moved with it.
What the standard says and what it does not
BS 5534 is the British Standard that guides how pitched roofs are tiled and slated. The current edition is BS 5534:2014+A2:2018. A code of practice sets out how work should be done to a recognised level, but it is not a statute, and falling short of it is not a criminal offence in itself. It does set the yardstick that a surveyor or a dispute adviser would measure the work against.
So is mortar now banned?
No. Mortar is still a normal bedding material for ridge, hip and verge work, and plenty of sound mortar ridges remain on Somerset roofs. What changed in the 2014 revision, according to Marley, is that bedding alone could no longer be counted on to hold the tiles, so every bedded ridge needs screws, clips or similar fixings too. That is a change in what a sound job looks like, not a ban.
Marley also states plainly that installing to BS 5534 is not required by law. We mention it because the opposite claim turns up in doorstep sales talk, and it is not accurate. Our page on dry ridge against mortar sets out how the two methods compare for a whole roof.
Why new work is expected to be mechanically fixed
Mortar can crack with the movement of the roof and with weather. Once it loosens, the ridge tile it held can slide, and a tile that lands on a path is a harm to anyone beneath. That is the practical reason behind the standard, and it is why roofers now treat fixings as part of the job from the first tile to the last.
What does mechanically fixed mean?
It means each tile is held by a screw, a clip or a bracket into the roof structure, rather than by the grip of the mortar. A mortar ridge can meet this by adding fixings through or beside the bedding. A dry ridge meets it by using a system designed for the purpose and tested to BS 8612, the test specification that covers these systems.
A roofer who relies on mortar alone on a new ridge is working against current guidance, even though no law was broken. We read the roof, and where a new ridge is fitted, it is fixed mechanically to the maker's data sheet. Our page on BS 8612 and dry fix explains what the test covers.
Building Regulations, planning and your own roof
Replacing a ridge like for like is normally covered by Class C of permitted development on a house, so planning permission is not usually needed for the covering. Building Regulations come in where the work changes the roof more widely, and your building control body is the place to ask. In Taunton that is Somerset Building Control, on 0300 303 7790.
Does a listed or conservation home change the answer?
It can. A listed house keeps Class B and C permitted development rights, yet needs listed building consent as well for work that touches its character. A conservation area has its own set of rules, and an Article 4 direction may be listed for the street. Check with Somerset Council's planning team before altering the ridge finish on such a home, and do it before any materials are ordered.
None of this makes dry fix compulsory. It means you can choose between methods with your eyes open, and ask for either one to be fixed properly. Either choice is lawful. Our overview of dry ridge and verge work sets out how the options are surveyed and priced, and our page on dry ridge and planning permission goes further into consent.
How to choose when nothing forces you
With no legal rule pointing one way, the decision comes down to the roof beneath your feet. Dry fix suits many modern tile ranges and is quick to fit. A mortar ridge with mechanical fixings can be the right finish on a clay-tiled cottage where a moulded unit would look wrong.
What should I ask any roofer?
Ask which method they propose and why, and how each ridge tile will be held down. Ask for the answer in writing, with the fixing type named. A roofer who talks about mortar alone, or who says dry fix is required by law, is giving you a half-answer.
You can also ask to see pictures of your own ridge, which is what we supply after every survey, alongside the written quote. If your ridge has already loosened, a photo taken from the ground is enough for us to say which route fits, and what the survey would need to check.
More on dry fix and the rules
Does my building insurance require dry fix?
We cannot read your policy for you, and terms vary, so check the wording or ask your insurer. If a ridge has failed, tell the insurer first and keep your paperwork together. The Financial Ombudsman handles complaints about an insurer's decision once its own process is finished.
Can a mortar ridge still be repaired?
Yes. Cracked bedding can be cut back and re-laid, with fixings added so the tiles are held mechanically as well. Whether that is better value than a dry ridge depends on the condition of the tiles and the line beneath them, which the survey photos will show.
The full picture: Dry ridge and verge repairs in Taunton ยท More short answers