The short answer
Natural slate is the better choice where length of life and a fine, flat finish, and it is usually the right covering on a Georgian or Victorian house that was slated originally. Tiles cost less to buy and fit and suit roofs that were tiled to begin with. The deciding points are what the roof carried before, what the structure can bear, and what the planning officer will accept.
Looks: what each covering does to a house
Slate is thin, flat and dense, so it lies close and casts a sharp, even shadow line at every course. Welsh slate has a cool blue-grey to purple tone that shifts with the light. Spanish slate is darker and plainer. On a terrace with a parapet, or a Victorian villa with a steep main slope, that fine texture is part of the architecture, and it is difficult to imitate.
Tiles read differently. Clay plain tiles are small, slightly cambered and warm in colour, and they give a roof a soft, hand-made texture. Pantiles are large and curved, with a strong rolling profile. Concrete interlocking tiles are bigger still, so they show fewer joints and look flatter and heavier on the roof.
Matching matters more than taste here. A house that has always had one covering looks wrong with another, and the change shows from the street. In Bath, the Bath Preservation Trust backed a swap from artificial slate to real Welsh slate on one terrace, a sign of how closely the covering gets read. Where a house is listed or stands inside the conservation area, the covering is something you agree with B&NES before work starts, not something you pick from a catalogue.
Life: how long each one lasts
Natural slate has the longest sourced life. MyBuilder's 2026 cost guide puts Welsh slate at over a century and natural slate overall at 75 to 100 years or more. The same guide gives fibre-cement slate 30 to 50 years, which is a different product altogether.
Tiles vary a good deal. The same guide gives clay plain tiles 40 to 60 years and concrete interlocking tiles 30 to 50 years. Marley's own article cites a BRE minimum of 60 years for clay, while the Building Conservation Directory says peg-tiled roofs have lasted several hundred years, so these are typical figures, not limits. Reported stone tile life is about a century, though that comes from a single surveyor's source.
All of these figures depend on exposure, fixing and upkeep. MyBuilder notes that poorly fixed slate can fail inside ten years whatever its quality. The covering is rarely the weak point. Nails, battens, underlay and lead usually give out first, which is why a good roof is judged on the whole build-up and not on the slate or tile alone.
Weight and what the structure can carry
Slate is thin, so a slate roof is lighter than most concrete tile roofs and lighter than reconstituted stone. Concrete interlocking tiles and thick clay tiles weigh more per square metre. The only laid weight we can quote from a published source is for reconstituted Cotswold stone slate, at about 84 kg per square metre, so ask for the data sheet of any product you are considering.
Weight matters for two reasons. The first is the structure. Rafters and purlins sized for slate may not suit a heavier tile. The second is the Building Regulations. Planning Portal says approval is required when a new covering makes the roof covering 15 per cent heavier or more, and the timbers then get a structural check. Putting concrete tile where slate was is the usual way to trigger that, and it can mean strengthening timber you would rather leave alone.
Our page on slate fixing methods explains how the slates are held, which also affects how much load the battens and rafters see.
Cost: what the cost guides report
Typical UK ranges reported by MyBuilder (2026) put natural slate at £100 to £180 per square metre installed, with Welsh slate at £140 to £180 and Spanish at £100 to £130. A semi-detached house in Spanish slate is reported at £7,000 to £10,000. Whole-roof replacement of any kind is reported at £5,000 to £12,000, and tiles tend to sit nearer the bottom of it than slate does.
Those are national figures, not an Empire price list. Scaffold, access, the shape of the roof, the state of the timbers and any heritage detailing all move the total. Buying the covering is only one line of the bill, and slate that lasts twice as long spreads its cost over more years.
Stone tiles sit above both. Stone tiles are dealt with in our answer on what a stone tile roof costs. Your own fixed price follows a survey of your roof, in writing.
Which to choose for your house
Start with what the roof was built with. If it carries natural slate, keep natural slate: it is the match, the likeliest to be accepted if the house is listed, and the one with the longest life. If it carries clay or concrete tiles, tiles of the same kind keep the proportions and the load the timbers were designed for.
Move away from the original only when there is a reason. Weight is one, since a lighter covering can relieve a tired structure. Budget is another, though the cheaper covering is not always the cheaper roof over fifty years. Appearance is the third, and in a conservation area it is the one the council will test hardest.
Brown streaks down a grey roof usually trace to poor fixings or a low-grade slate, and our note on rust stains on slate explains how to tell which. For a decision on your own roof, our slate roofing service begins with a free survey, and it helps to check first whether the roof timbers were built for the weight of slate or of concrete tiles.
