What is a major disadvantage of a slate roof?

Cost is the drawback that counts most. Checkatrade's slate guide, with a pricing table dated September 2026, puts natural slate at £160 to £210 per m², averaging £184, with Spanish slate at £95 to £125. The firm's repair guide, table dated June 2026, prices repairs at £150 to £220 per m² on natural slate, against £90 to £120 on concrete tile.

Those are typical national ranges from one publisher, and not a quote for your house. The gap still shows up on real roofs. Slate is slower to lay, and a slater commands a higher day rate, which the same guide gives as £280 to £360. Find out if VAT and scaffold sit inside any number you are quoted. Ours is one written total, built from photographs of your roof once the survey is done. The page on slate roof cost per square metre goes into the arithmetic.

A slate is a thin piece of stone held by a nail or hook. It splits if trodden on, knocked by a ladder or struck by a falling branch, and replacing one means working from the roof, sliding a tool under the course above. That is slow, skilled work, and it explains why a small repair can cost more than a similar job on tiles.

The sensible advice for owners is to keep off the roof, and to avoid a pressure washer, since both break slates. Our answer on walking on a slate roof explains why, and how roofers cross it without damage. A cracked slate left alone lets water through to the batten, so small faults are worth dealing with before the next gale arrives. Gutters matter too: a blocked run spills over the eaves slates and soaks the timber beneath them, and a leaning ladder resting on that edge is another way slates get cracked.

Slate cannot go on any roof. Slopes below 20 degrees are too flat for natural slate of 500 mm length where exposure is moderate, per Cupa Pizarras' reading of BS 5534:2014+A2:2018, and hook fixings are ruled out under 25 degrees. A shallow porch, a flat-roofed extension being pitched, or a dormer cheek may be too flat for the slate you want, and a covering made for lower slopes is then the better choice.

The headlap, the stretch of each slate hidden under the course two rows higher, grows as the slope flattens and the exposure rises. For a 500 by 300 slate laid at 20 degrees on a sheltered or moderate site, Cupa gives 115 mm. We measure the pitch during the survey instead of guessing from the ground, because a wrong guess leaves a roof that leaks in driving rain. The page on slate roof minimum pitch goes further.

Slate is a stone covering, and heavier than some alternatives. When a roof moves from a lighter covering to slate, the structure may need checking. The Planning Portal brings building control approval into play where a new covering is 15 per cent heavier or more, and wants a surveyor or structural engineer to look at the roof first whenever the new material differs a great deal in weight from the old.

Going the other way matters too. Swapping slate for something cheaper changes how a period house looks, and in a conservation area or a listed building it can need consent. The same applies underneath: if the battens and underlay are old, the slates will outlive them, and a re-slate is the chance to renew both. It is cheaper to do that once, with the slates already off, than to open the roof again in ten years for the sake of a few rotten timbers. Good slates come off carefully and go back on, so the saving is real.

The drawbacks are real, and most are paid at the start. CORC gives well-maintained slate 100 years or more, and Checkatrade says stone slate can pass a hundred. Those are typical ranges and not promises, and the fixings and underlay do not always last as long as the stone, which is a point our slate roof lifespan page takes further, since the age a roof reaches depends on how it is fixed and kept.

On a period home slate also keeps the look the street was built with. Arun District Council's Aldwick Road conservation area guidance records that original slate was often replaced with modern interlocking concrete tiles, which it says harm the buildings and the street. So slate is not a bad buy, whatever the first invoice suggests. It is a covering to choose with the cost, pitch and handling in mind, and to repair sensibly. Our slate roofing page explains the options.