When a stone slate roof starts to leak, owners often fear the worst. In practice the covering itself is rarely finished. The district's 2000 guidance puts it in plain terms: a Cotswold roof that is regularly maintained can easily last 100 years, and could last as long as 200 or 300. The authors also say that annual scraping could double a roof's life. That is a long time to get from one set of battens, which is why renewing the fixings is the usual repair.
Q2.1When is strip and re-lay the right repair?
Where a slope has fatigued, the right job is to strip it carefully, sort every slate by length, discard the cracked ones, renew the battens and fixings, then lay the sound stones back in courses. The guide notes that a good number of slates can turn out to have perished once a roof is stripped, so a quote should allow for topping up with new stone. We photograph every stripped slope, so you see what has been kept and what has been replaced, slate by slate.
Q2.2Where should replacement stone come from?
Sourcing matters. Heritage policy reproduced in the guidance says new stone slates are preferable to second-hand, and slates lifted from a roof belong on that same roof afterwards, never on a different house. The two kinds of stone, sandstone and limestone, must never be substituted for one another. Whatever stone is added, we tell you where it came from. A patch for your roof should never come at the cost of someone else's, and stone taken from another building is a loss to that building.
Q2.3How should a stone roof valley be made?
A swept valley is a curved internal junction, formed by specially cut slates, where two slopes meet. The guidance prefers it to a lead-lined or mitred valley, though a well-made lead valley is a sound repair where the original has gone. Our lead roofing page covers the lead side of the work.