From the street, many Cotswold roofs look alike. Underneath, they can be very different in weight, lifespan, repair cost and what the planners will allow. Here’s a plain-English guide.
Cotswold stone slate
At a glance: local limestone split into thick, uneven, honey-coloured slates. Very heavy. Can last centuries if re-laid and maintained. Repairs are costly because the work is skilled and reclaimed slates are scarce.
This is the traditional Cotswold roof. Slates are laid in “diminishing courses”, big at the bottom and small at the top, on steep pitches. Historically they were hung on oak pegs; later on nails.
The slates themselves can last for centuries. What fails is usually the fixings. Rusted nails or rotted pegs let slates slip, known as “nail sickness”. The usual fix is to strip the roof, keep the good slates and re-lay them, topping up with reclaimed slate.
Watch for: slipped or missing slates, dips in the roof line, daylight in the loft, and failed cement repairs or torching.
Natural slate
At a glance: thin, flat slate quarried in Wales, Spain and elsewhere. Smooth, dark grey or blue-grey, even sizes. Light to medium weight. Often 60 to 100+ years for good-quality slate.
Common on Victorian and later homes and some outbuildings. Quality varies a lot. Good Welsh slate can outlast its owners; some cheaper imported slate weathers faster or contains minerals that rust and stain.
Watch for: slipped slates, lead clips (“tingles”) holding slates in place, flaking or rust staining, and worn ridge and valley details.
Manufactured slate
At a glance: fibre cement, concrete or resin made to look like slate. Very regular and uniform. Light (fibre cement) to heavy (concrete). Often 30 to 60 years depending on the product.
Fibre cement and concrete slates became common from the 1970s. They’re cheaper and quick to lay but don’t last as long. Older fibre cement slates (roughly pre-2000) may contain asbestos: usually safe left alone, but removal must be done by a licensed contractor and costs more. Concrete tiles are much heavier than slate and, swapped onto a roof built for slate, can overload the timbers.
Watch for: curling, cracking or moss-covered slates, sagging roof lines, and signs the roof was re-covered without the timbers being strengthened.
Listed homes and conservation areas
Replacing stone slate with natural or manufactured slate on a listed home will usually need listed building consent, and may be refused. In conservation areas, changes to front roofs may need planning permission. If a previous owner swapped materials without consent, it can become your problem.
What to ask before you buy
When was the roof last re-laid or recovered, and by whom?
Are there any guarantees, and do they transfer to you?
Have any materials been changed, and was consent obtained?
Has anyone checked the roof timbers recently?
How we help
We recommend a RICS Level 3 Building Survey for Cotswold stone homes. We use a 9-metre pole camera to see roof slopes, ridges and leadwork that can’t be reached safely, and we tell you clearly what’s normal wear and what needs attention. Lifespans vary with quality, fixings and maintenance, so your survey will comment on the roof you’re buying. After your report, our helpful guides explain your next steps.
Buying a Cotswold home? Use the Get My Quote button above, or call our Cotswolds line on 01451 828107.
Max Daniel AssocRICS, Director, MJD Residential Surveying