The short answer
Natural slate is usually worth the extra cost if you plan to keep the house, because it can last 75 to 100 years or more where man-made slate is typically quoted at 30 to 50. Spread over those years, the dearer roof often costs less per year. It is also the right covering where a listed building or conservation area expects real slate.
What the extra cost actually buys
A natural slate roof costs more up front than most alternatives, and the gap is real. Typical UK ranges reported by MyBuilder (2026) put installed slate roofing at £100 to £180 per square metre. Spanish slate sits at the lower end, around £100 to £130, and Welsh slate at the upper end, around £140 to £180. The same source gives £7,000 to £10,000 for a whole semi in Spanish slate. Our slate roofing quote follows the survey, and it will depend on the slate, the shape of the roof, the scaffold and the detailing.
What that money buys is mainly time. Slate is a dense stone that does not rot, rust or lose its colour the way cheaper coverings can. The material is not the weak point on a well-built slate roof. The fixings and the timber beneath are, and both are renewed during a proper re-slate.
How long each covering typically lasts
Read the figures below as typical ranges, not a promise: how exposed the roof is, the standard of the laying and the upkeep it gets will all shift them.
| Covering | Typical life |
|---|---|
| Natural Welsh slate | 100 years or more |
| Spanish slate | 75 to 100 years |
| Clay plain tiles | 40 to 60 years |
| Concrete interlocking tiles | 30 to 50 years |
| Fibre-cement slate | 30 to 50 years |
The figures come from MyBuilder's slate roof guide (2026). Sources do not always agree, and one natural-slate supplier puts fibre-cement at 30 to 40 years, though that supplier has an interest in the comparison. The same guide cautions that slate fixed badly can give out within ten years even when the stone is good, so the fixing counts for as much as the quality of the slate.
Cost per year rather than cost per roof
A simple way to compare is to divide the price by the years the roof is expected to last. This is arithmetic on the ranges above, not a quote.
- Welsh slate at £140 to £180 per square metre, over 100 years, comes to about £1.40 to £1.80 per square metre for each year.
- Spanish slate at £100 to £130, over 75 to 100 years, works out at roughly £1.00 to £1.75 per square metre for each year.
For the cheaper coverings, we have no sourced installed price per square metre, so we cannot complete the comparison with a number. What the table does show is the shape of it. A covering that lasts 30 to 50 years is replaced two or three times in the life of one slate roof, and each replacement brings scaffold, strip-out, disposal and labour again.
That is the real argument for slate. It is a larger single payment that avoids repeating the same costs. If you are selling in a few years, the case is weaker, and a cheaper covering might make sense for you.
When natural slate is not the right call
Natural slate is not automatically the answer. It is heavy compared with some coverings, so the structure has to carry it. Weight matters in the rules too. Where a new covering material makes the roof covering 15 per cent or more heavier, the Planning Portal requires Building Regulations approval, and the rafters get a structural check.
Pitch is another limit. Cupa Pizarras, quoting NHBC, gives 20 degrees as the usual minimum for natural slate, subject to headlap, and BS 5534 reaches 20 degrees in moderate exposure only with a 500 mm slate and a 115 mm lap. Below that, a different covering or a different roof system is a better fit.
On a short-term let, a garage or an outbuilding that will not be seen, a lower-cost covering can be the sensible choice. Where that applies we tell you, because a roof should be matched to the building and your plans for it.
Where slate is expected in Bath
In Bath the value question sometimes answers itself. Changing the covering of a listed building can need listed building consent, which B&NES Council decides. The city-wide conservation area covers 1,486 hectares, roughly half of the 2,900-hectare World Heritage Site. On Lambridge Place the Trust favoured natural Welsh slate over the artificial slate it replaced. In those settings a cheaper man-made slate may be refused, and a refused scheme costs more than the saving.
The roof as it was built is often natural slate, and our approach is to keep it that way. A house with Welsh slate stays Welsh slate. Our page on matching slate colour covers how closely a replacement can follow the original, and reclaimed slate is a lower-cost route to real slate where the supply allows.
Deciding for your own roof
Weigh up four things: how long you will own the house, any listing or conservation status, the covering on the roof today, and what share of the old slate is healthy enough to reuse. A sound stock of slate can be sorted, stacked and relaid, which is where much of the saving on a re-slate comes from. If you are keeping the house and the roof is already slate, repair or re-slate in slate is usually the stronger choice. If much of the slate can be reused, the price drops further, because the cost of a re-slate falls with every sound slate that goes back on.
Number of slates per square metre also feeds into the price, and our answer on how many slates are needed per square metre shows how size and lap change the count. Before deciding, ask the roofer to count how many existing slates are sound enough to go back, since that one number shifts the comparison between slate and a cheaper substitute more than anything else.
