The short answer
Choose by the roof you have and the pitch you can build. Slate belongs where slate is already up there, and clay where clay is, because the look is part of the building. Slate is thin, flat and grey, and CORC quotes 100+ years for slate. Clay tiles are warmer and more textured, and the BRE sets a minimum life of 60 years for them.
Both coverings suit Somerset, and both have a long history here. The right one is usually the one already on your roof.
Look and character
Slate is thin, flat and smooth, in greys, blues and greens, and it lays in crisp, regular lines that catch the light. Clay tile is thicker, with a warmer colour and a surface that changes from one tile to the next, so a clay roof looks softer and more uneven in the light. Some clay tiles are plain and flat, laid in overlapping rows, and others are curved, such as pantiles.
Which looks right on an older home?
The material it was built with. A Victorian terrace in slate looks wrong in clay, and a cottage in clay tile looks wrong in slate. Somerset has its own clay tradition. The South West Heritage Trust says Bridgwater made tiles, terracotta plaques and other wares that built the look of Somerset's brick-and-tile towns, and a local leaflet counts the Bridgwater Double Roman tile among the yard's later products.
A swap of material changes the face of a street. For that reason, on an older house whose roof gives it much of its character, we put a like-for-like covering first and only discuss a change when there is a clear need for one.
Weight, pitch and life
The two coverings make different demands on the roof. Pitch limits are the clearest. Natural slate, Cupa says, bottoms out at 20 degrees under BS 5534. Marley's figures for clay run from 40 degrees for its Canterbury tile through 35 for Ashdowne and 30 for Hawkins, while its Lincoln clay pantile goes as low as 15. Whichever you choose, the maker's sheet for that product decides the final figure.
How long does each last?
For slate, CORC (the Confederation of Roofing Contractors) quotes 100+ years where the roof is well cared for. For clay, Marley cites the BRE as giving a minimum life expectancy of 60 years, and that figure covers clay only. A building conservation article cautions that old peg tile is not reliably described by it. These are typical ranges, not promises.
Weight matters when you swap. The Planning Portal sets the line at 15 per cent: the Planning Portal says Building Regulations approval is needed when a new covering raises the roof's load by 15 per cent or more. It recommends a structural check before you commit to a heavier material.
Conservation and listed homes
A listed house, or a home within a conservation area, may leave you little choice. Under permitted development, Class C usually lets a house be re-roofed in the original material. A listed house still needs listed building consent where the character of the building is touched. A different material changes how the building looks, so the planning team must be asked first, and the answer can take time, which is worth building into your plans before you book any work.
Who do I ask in Taunton?
Somerset Council's planning team deals with Taunton's conservation areas and listed buildings. In the National Park on Exmoor, the planning body is Exmoor National Park Authority, and the council steps back from that decision. At the survey we tell you which route your home falls under, and what that route asks you to submit. Our answer on slate roofs in a conservation area goes deeper into the process.
A short list of what the roof is covered with now, plus dated photos, helps whichever body you write to, because it shows what a like-for-like repair would mean in practice and saves a round of questions.
A plain way to decide
Start from the covering that is on the roof today, since matching it is the safest choice for the look and for consent. Next check the pitch of every slope, because a shallow slope can rule slate out. After that, think about weight, because a heavier covering may call for a structural check, and about how many years you expect to live there. A survey puts real figures against each point, and you see the photos that support them. If two options are close, we tell you plainly, along with what would tip the balance one way or the other.
Can I switch from clay to slate or back?
You can, but the roof structure, the pitch, the weight and the consent route all need checking first, and on a protected home the answer may be no. We read the roof, show you pictures of its battens and rafters, and set out what a switch would involve before a price is given. Read about our slate roofing work, compare natural and fibre cement slate, then send a few pictures of the roof to begin.
If you are unsure which material you have, our survey identifies it, because slate and its lookalikes are easy to confuse from the ground.
More on slate and clay
Is clay cheaper than slate?
That depends on the product, the area to be covered and the way we reach it, so a price follows only after the survey, in writing. National cost guides give typical ranges for tiles and slate. Look at each guide's date and what it covers, and make sure any quote you get states whether VAT and the scaffold are included.
Do clay tiles need more upkeep than slate?
Both need the same kind of care: clear gutters, a look after storms, and a check on the ridge and flashings. Clay can grow moss on a shaded side, and slate can lose slates when its nails fail. A survey every few years catches either early.
The full picture: Slate roofing in Taunton ยท More short answers