Should a Shipton roof wear stone slate, the stone is the valuable part. Cotswold District Council's technical guidance for owners states that with regular upkeep such a roof can easily last 100 years. It dates from 2000, but it describes how these roofs have always been looked after.
Q2.1Why do the fixings give up first?
Each traditional slate hangs from a wooden peg pushed through a small hole near its upper edge, with the peg resting over a timber batten. Pegs go soft, battens decay, and slates drop out of line long before the stone itself is spent. That is how a roof can leak badly while most of its covering is still sound. Stripping the slope, renewing battens and fixings, then laying the same slates back in order is the repair that respects the roof.
Q2.2What are diminishing courses?
The largest slates run along the eaves, and each course above steps down in size towards the ridge, which roofers call diminishing courses. A good repair keeps that pattern. Random sizes, or sawn pieces cut all to one dimension, look wrong from the lane and sit badly on the slope. The guidance also cautions that concrete tiles and similar substitutes do not suit historic buildings.
Q2.3Can the old timbers carry a different covering?
Stone slate is very heavy, and the timbers under it were built for that load. Moving to another covering, lighter or heavier, alters the loading, and a covering 15 per cent or more heavier requires approval under the Building Regulations. We check the structure before quoting, and our Cotswold stone roofing page sets out how we approach these roofs.
If yours is clay tile or slate instead, the same idea applies: keep whatever is sound and renew whatever is tired.