Natural slate is rock, split from a quarried block into thin sheets. Fibre cement slate, and other man-made slate such as resin or composite, is a manufactured product pressed or moulded to resemble it. People compare them because the man-made kind is usually presented as the cheaper route to a slate look, and because buyers are rarely shown the trade-offs next to each other.
The comparison below keeps to published figures and says plainly where none exist. It is about slate against slate; for the question of slate against clay or concrete tile, read is slate more expensive than tiles. For the wider service, see slate roofing in Stroud.
What separates a split stone from a pressed board
A natural slate is a metamorphic rock that breaks cleanly along its grain. Each one is cleaved by hand or machine from the block and trimmed to size, so the thickness, the edge and the surface vary slightly from slate to slate. That variation is part of the finished look.
A fibre cement slate is made from cement reinforced with fibres, formed in a factory into uniform sheets, and coloured to resemble slate. Because it is manufactured, every unit in a batch matches its neighbours, and it can be supplied with holes already formed. Other artificial slates use resin or composite materials and behave differently again, so a general statement about one does not always hold for another. The product data sheet is the authority on pitch, fixing and lap for any specific make.
Where the origin matters
Natural slate carries a source: Welsh, Spanish and other quarries each have their own character, which our page on Welsh against Spanish slate covers. A manufactured slate has a brand and a range of colours instead. That difference shapes the next questions about age, look and fit on an older house.
Lifespan: what the published ranges say
On lifespan the published figures differ widely between the two. MyBuilder's slate roof guide, updated in August 2026, gives natural slate 80 to 100 years or more, reports Welsh slate often passing a century, and gives Spanish slate 75 to 100 years. It puts synthetic or fibre cement slate at 30 to 50 years. CORC, which advises on roof conservation, reckons well-kept natural slate can reach 100 years and beyond.
Read these as typical spans; exposure, how well the job is done and how the roof is looked after all move them. A manufacturer's guarantee is also a different thing from a lifespan: a guarantee period is the maker's commitment on the product, and it tells you nothing about how long the covering will really last.
Why the gap exists
Stone does not rot, and its colour is the colour of the rock. The commonest end to a natural slate roof is the failure of the fixings, not the slate, as covered in our slate roof repairs guide. A cement-based product ages through its binder and its surface, and its fixings depend on the same factors, so the covering and its nails both set the limit.
Appearance close up and from the lane
From a distance, a good manufactured slate and a natural one can be hard to tell apart. Up close the differences show. Natural slate has an uneven surface, a slightly irregular tail line and subtle shifts in tone from slate to slate, and it weathers in a way that reveals the stone's mineral bands. Man-made slate tends to look more uniform and the edges are regular, which some owners like for a modern extension.
Colour over time
Weathering is the other difference. Natural slate keeps its colour for decades. Some man-made products change over the years as the surface wears or lichen takes hold, and the change may not be even across a roof. When only part of a roof is being mended, a new slate of either type will look different from a weathered neighbour at first, which is why we match carefully and sometimes use reclaimed slates for patches.
Light also behaves differently. A slightly rough natural surface catches low sun and shows depth, while a flat manufactured face can read as a single plane. Neither is wrong; it is a matter of what the house and its neighbours call for. We photograph samples against your own roof when that helps the choice.
Size and lap
Manufactured slates come in set sizes, while natural slate comes in a range of lengths and widths. The size you choose affects the headlap and the minimum pitch, as described in slate sizes and headlaps. A roof designed around one product cannot simply switch to another of a different size without the batten gauge being reworked.
Cost: what is sourced and what is not
For natural slate there are published installed figures. MyBuilder's guide gives £100 to £180 per m2 installed, with Welsh slate at £140 to £180 and Spanish slate at £100 to £130, and a slater's day rate of £200 to £300. It puts a semi-detached house roofed in Spanish slate at £7,000 to £10,000. Checkatrade's roof repair guide gives £150 to £220 per m2 for natural slate repair.
No installed price for fibre cement or other man-made slate has turned up from a source we can cite, so none appears here. If a supplier tells you their product is a fraction of the price of natural slate, ask for the installed figure for your own roof, including scaffold, underlay, battens, fixings, labour and waste, and compare like with like.
Cost over time
The roof that costs least over thirty years is not always the one that costs least to buy. A covering that needs replacing twice in the span of one natural slate roof carries two lots of scaffold, strip and disposal. Whether that works out in favour of either material depends on the real life of the product and the care it gets, which no national average can settle for your house.
If you want both options costed, the written quote shows them side by side.
Weight, structure and the Building Regulations
The roof structure was built for the covering that sat on it. Changing the covering changes the load, and the rules take that seriously. A heavier covering is the first trap. Under the Planning Portal's wording, a rise of 15 per cent or more in covering weight needs Building Regulations approval; Approved Document A talks of loading increased by more than 15 per cent. The two sources differ slightly in wording, so check with your building control body.
We do not publish weights for either type here, because they vary by product and thickness. For natural slate, the weight depends on the quarry, the size and the thickness, and for man-made products it depends on the make. The data sheet gives the figure, and if the new product is the heavier of the two, a structural check comes first. Our page on slate weight checks covers the process.
Fire performance
A second trigger is fire performance: a covering that differs significantly from the existing one in that respect also needs approval, per the Planning Portal. The fire rating belongs to the product, so it is another item to check on the data sheet when swapping between natural and man-made slate.
A re-roof that renovates over half the roof surface can also bring in a Part L thermal upgrade.
Conservation areas, listed buildings and what is accepted
Planning permission is seldom needed for a true like-for-like re-roof, but everything hangs on the word like. Swapping natural slate for another material can alter how a building looks. Stroud District Council's position is that the listed status of a building covers all of it, inside and out. Put the proposed covering to the conservation team before you commit.
Stroud District has 41 conservation areas, and Article 4 Directions in five of them. Nothing on the council's page says if a direction reaches roof coverings, so that question goes to the planners.
What the sourced policy says
The firmest policy statement we can cite concerns stone slates, not natural slate. A 2000 Cotswold District Council guide reproduces English Heritage policy describing substitutes such as fibre resin, concrete and reconstituted stone as unsuitable for historic buildings roofed in real stone slate. We have not found a current published rule for Welsh or Spanish slate in the same terms, so we do not claim one. In practice, officers usually want the covering to match what was there, and on a Victorian terrace that means natural slate. Our guide to Victorian slate roofs explains the matching in more detail.
For a listed home or one in a designated area, agree the covering with the council before ordering. That one step avoids a costly redo.
Repairing, matching and the older artificial roof
Repair is where the choice shows up years later. A natural slate roof can be mended slate by slate with a matching natural slate, and sound slates can be lifted and reused. A man-made slate is usually discontinued within some years and the exact colour or size may not be available; a mixed-material patch can show from the ground.
Roofs of unknown age
If a roof of uncertain age carries artificial slates, it is worth having the material identified before it is disturbed. Older cement-based sheets may contain asbestos. Under HSE guidance, carefully lifting asbestos cement roof sheeting without breaking it counts as non-licensed work. Where it is substantially broken, the work becomes notifiable non-licensed work. We handle this carefully and the survey will tell you what applies.
Fixings and underlay
Whatever the covering, the layers under it need to suit it. Battens must be spaced to the product, the nails or clips must be the type the maker or the standard calls for, and the underlay must be chosen with the loft ventilation in mind. A new covering on tired battens and old nails throws away the extra life you paid for.
Which to choose
The choice is rarely one-sided. Natural slate suits a heritage house, a long ownership and a roof whose structure is sound. A manufactured slate may suit a modern extension or a house where the budget is the limiting factor, and where no conservation constraint applies. We offer both, and we will not recommend a material that does not suit the building.
Whichever you pick, the work carries our 10-year workmanship guarantee, in writing.