Scotch Slate: Why Old Scottish Roofs Are Worth Saving

A hundred-year-old slate roof is not a liability. Done right, it is the best roof your house will ever have.

Until the quarries closed in the mid twentieth century, most of central Scotland was roofed in Scotch slate, from Ballachulish, Easdale and the other west coast workings. It is thicker and less regular than Welsh slate, laid in diminishing courses, smaller slates towards the ridge, over solid sarking boards rather than open battens. That construction is why so many survive: the boards stiffen the roof and back up the slate.

The slate itself often outlives everything around it. What fails on an old Scottish roof is almost always the iron nails, the lead flashings, the mortar on ridges and skews, or the sarking where a leak has been left. This is why the honest answer to an old slate roof is rarely a modern replacement and often a careful repair, or a re-slate that reuses the sound original slates on new fixings.

Matching matters. Scotch slate has a character, in thickness, texture and colour, that concrete substitutes and thin imports do not share. On a repair we match size and coursing so the patch disappears. On a re-slate we grade and reuse what is sound, making up the difference with matching reclaimed stock.

If your slate roof is shedding the odd slate each winter, get it looked at before the sarking pays the price. It is usually a smaller job than owners fear, and it keeps a roof that was built to last another generation doing exactly that.

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