Slate Roofing Pros and Cons: 3 Real Advantages, 5 Honest Disadvantages

Two years ago, a returning customer from Yorkshire phoned me about re-roofing his farmhouse.

The house was built in 1904, originally covered in local sandstone slates. He had two quotes on the table: one from a local slate specialist, one from a general roofing firm that undercut him on price and promised the job done in three months.

He asked me a simple question: "Is it worth it?"

I told him he had to answer a different question first. Do you want a 120-year roof, or a 20-year roof? Because that single answer decides which material you buy, which crew you hire, and how much you should expect to pay.

That is what this article is about. I am not going to tell you slate is wonderful and leave it there, because that would be a half-truth. I sell slate, yes, but I have also spent thirty-odd years watching what happens when it is bought badly, fitted badly, or matched to the wrong building. So here is the honest version: the genuine advantages, the genuine disadvantages, and the numbers that should drive your decision.

First, the Baseline: Slate vs the Other Three Options

You cannot judge the pros and cons of slate in a vacuum. So here is the comparison table I draw on the back of an envelope when an importer asks — lifespan, weight, cost and installation, for the four roofing families you will actually choose between:

Material	Typical lifespan	Weight per m²	Relative cost	Installation
Natural slate	75–150 years	30–45 kg/m²	Highest	Specialist slater
Clay tiles	50–100 years	40–60 kg/m²	High	Standard roofer
Fibre-cement	30–50 years	10–15 kg/m²	Low	Standard roofer
Asphalt shingles	15–30 years	8–15 kg/m²	Lowest	Standard roofer

I left prices out of the table on purpose. A square metre of slate can cost two or three times more from one quarry than another — Spanish, Welsh and Chinese Jiujiang slate sit in different price bands, and so does their performance. So before you compare "slate vs shingles" on price, remember this one line: slate is the only roofing material designed in decades-of-a-century, not decades-of-a-decade.

Everything below follows from that.

Advantage 1: It Actually Lasts a Century (and This Is Not Marketing)

Ask any roofer in Britain how old the slates are on the house he is repairing today, and he will point at roofs that have been up 120, 150 years without replacement. Slate does not do that because someone is good at selling it. It does that because of the rock.

Slate is mudstone cooked and squeezed by geology until its mineral grains lie in parallel sheets — that grain is called cleavage, and it is what lets a block split into tiles in the first place. The same grain is why the finished tiles have a very low water absorption (typically below 0.5%), survive hundreds of freeze–thaw cycles, and hold a flexural strength of 60 MPa or better at S1 grade. These are not claims in a brochure; they are measured to EN 12326 and ASTM C406, and a serious supplier will publish the numbers. We publish ours, every batch, on our slate test results page.

But here is the honest cold water. A 100-year slate roof is the result of the right slate plus the right installation. Slate will not rot, rust or be eaten by insects — but nails rust, roofers make mistakes, and moss will find a home if you ignore it. In thirty years I have seen far more failed slate roofs caused by bad workmanship than by bad slate. You are not buying a stone; you are buying "the right stone, fitted right". Get both and you have a family heirloom.

Advantage 2: It Is Beautiful, and It Gets Better Looking

Slate's colour is not painted on. Iron makes it purple-red, chlorite makes it green, carbon makes it near-black — every tile carries a slightly different face, and a finished roof has a kind of living, non-repeating texture that no factory-formed tile can copy. It is why old towns, cathedrals and farmhouses across Europe still wear the same material after centuries.

If you are building a home with any character — a farmhouse, a guest house, a project that will be photographed — slate does something to the whole building that no shingle can. Buyers tell me all the time: "I can't say why, I just like it." That is slate working on them.

If you want to match colour to your building rather than hope for the best, our slate colours guide explains how each colour forms and which suits what architecture.

Advantage 3: It Does Not Burn, Blow Off, or Soak

Three physical gifts, all from the same rock:

• Fire. Slate is inert. In wildfire zones, a slate roof is often the last thing standing — and building codes have trusted it for centuries in fire-prone regions.
• Wind. Slate roofs are nailed or hooked per slate and interlock course on course; on exposed coasts, slate is the traditional, proven answer to gale-season Atlantic weather.
• Water. With absorption under 0.5%, water never gets inside the tile — it runs off the surface, guided by the slight ripples of the natural cleft. That is why a slate roof stays dry in driving rain that would push under an asphalt shingle.

Those three points are exactly the three weakest points of asphalt. Asphalt roofs start degrading in a decade or two; slate is still on the same house a century later. That is why heritage and listed buildings are almost all natural slate.

Disadvantage 1: It Costs Real Money (and Not Just in the Stone)

Now the honest half. I will not polish it.

Slate roofing is expensive. Five to ten times the material cost of asphalt shingles, three to four times fibre-cement. And the premium does not stop at the tile:

• Freight. Slate is dense. A 20-ft container of slate hits its 22–24-tonne weight limit before it is physically full — importers learn this on the first shipment. Always ask whether a quote is per square metre or per tonne.
• Labour. A slate roof must be fitted by a slater, not a general roofer. In slating countries (UK, Ireland especially), slater day rates run well above a roofer's, and good ones are booked out.
• Structure. The roof has to carry 30–45 kg/m². If your trusses or ceiling were built for shingles, you may need reinforcement before a single tile goes up.

The line I give every importer is simple: slate is not expensive per tile — it is expensive because every part of the job has to be done to slate standard. Fit slate with shingle-grade habits and you will have spent a fortune to build something that leaks.

Disadvantage 2: It Is Heavy — It Sits on the Building for a Century

Same roof area, the slate covering outweighs shingles by roughly 20–30 kg/m². On a 100 m² roof, that is an extra two to three tonnes sitting up there — permanently. Two to three small cars parked on your rafters.

Two practical consequences:

1. Check the structure first. If you are re-roofing an old timber house, get a structural engineer to confirm the loading before ordering anything. If the answer is no, the honest answer may be a different material.
2. You pay for the weight twice. Once in freight, once in the labour of lifting it onto a roof. That is a big part of why slate costs more per m² than fibre-cement — you are buying both the stone and the man-power.

The good news: slate comes in different thicknesses — 5 mm, 6 mm, 8 mm — and the difference is real. If your structure is tight, the 5 mm grade is noticeably lighter. Our weight guide shows what each thickness actually loads on your roof.

Disadvantage 3: It Needs a Slater, Not "a Roofer"

This may sound precious, but it is the honest truth of the trade.

Laying slate is a craft, and the details are exactly where leaks are born: how the headlap is set, where the nails go, how the courses lap from below, how the verge and ridge are closed, how the flashings are finished. Get the headlap wrong, and wind-driven rain slides up under the tile. Get the nailing wrong, and a strong gust lifts a slate like a lever.

Take headlap alone: in British practice it is usually a minimum of 75 mm, more on windy elevations. Set it short and rain gets in; set it overlong and you cut the covered area per square metre — paying for slate you cannot see. None of this is guesswork a first-time roofer can improvise.

Hire a roofer who has never slated, and the instinct to treat slate like clay tile is too strong. The slate might look fine for a year. The trouble, when it comes, comes with interest. A good slater costs more per hour and is worth every extra penny.

Disadvantage 4: Replacement Slates Are Hard to Match

Slate is not a tile you re-order from a warehouse. Because its colour and grain come from the rock, every quarry is different. When a slate breaks after forty years, you are matching colour, size, thickness and even grain direction — or you will end up with a patch that shouts at you from across the street.

Worse, some quarries have closed; some old roof colours no longer exist in new production. That is why restorers of old buildings spend real money tracking down salvaged slate from the era. We have had customers send a single broken slate to China by courier just so we can match its tone.

The cheap insurance is to order 5–10% spare at the start and store them. That pile of extras is the future — itself, written in slate.

Disadvantage 5: It Needs a Maintenance Routine — Not "Set and Forget"

Slate is tough, but "tough" is not "zero-care". Moss loves a slate roof: the mineral surface holds moisture in tiny pockets, and through freeze–thaw cycles that moisture can spall the surface and open a tile to failure.

The remedy is embarrassingly simple: look at the roof once a year, before winter. Clear leaves, pull off dead branches, deal with any moss patches. Half an hour a year buys you decades of trouble-free roof. That is the maintenance guide in one paragraph; the full version has the tools, the timing and the rules for when to call in a professional.

So Is It Worth It?

I have said the honest. Now the honest balance.

Every disadvantage listed above is a money and skill problem, not a material problem. If your budget carries, your structure carries, and you can find a real slater — the disadvantages stop being disadvantages. What remains is what no other roofing material can offer: a century of service plus a beauty that improves with age.

My advice has always been one sentence:

If the house is meant to last — the family home, the building you want to leave behind — and the budget allows, slate is the only material that turns your roof into an asset instead of a liability. If the house just needs to keep the rain out and the budget is tight, there is no shame in shingles. It is honest to want either.

If you have decided to look seriously, then the next step is to see the stone, not just the price list. Our roofing slate range comes from our own Jiujiang quarry, tested to EN 12326 and ASTM C406, each tile inspected before packing. But do not take our word for it — request samples, weigh them in your hand, tap them on the edge. A roof that has to last a century deserves a decision made from a sample, not a screenshot.

Frequently Asked Questions

What is the biggest disadvantage of a slate roof?

Cost and the need for a specialist. The material is several times dearer than asphalt, installation must be done by an experienced slater, and the roof structure has to take 30–45 kg/m². Skimping on any of those three turns an expensive roof into a leaking one.

How long does a slate roof last?

With quality slate and quality work, 75–150 years is normal; many European roofs pass 100 with no sign of giving up. The lifespan is decided by the slate's own numbers (absorption under 0.5%, flexural strength at least 60 MPa) and by the installation. See our lifespan guide.

Why is slate roofing so expensive?

Three reasons stack: slate of good quality is rare (only certain rock formations yield tiles); it is heavy, so freight and lifting cost more; and it needs skilled slaters whose labour is not cheap. The result is the most expensive roof material, and also the only one built to last a century.

Can you walk on a slate roof?

Briefly, yes, if you know where to step — on the headlap zone, never on the middle of an exposed tile. Habitual walking, or heavy loads, will crack slates. For every maintenance access, use a ladder and a professional. Details are in the maintenance guide and the repair guide.

Will a slate roof leak?

Good slate itself almost never lets water through — absorption is under 0.5%. When a slate roof leaks, the water is usually coming in at a detail: the valley, the flashings, the verge, a nail popped in the wind. That is why the quality of the slater, especially at the details, matters more than the brand of the slate.

Slate vs asphalt shingles — which is better?

It depends on what you are trying to do. Shingles are cheap, light, and quick to fit — but you will re-roof every 15–30 years. Slate is expensive, heavy, and requires a specialist — but it can be the last roof you ever buy. Over 100 years the cumulative cost of re-shingling three or four times usually exceeds the slate roof. Compare it all in our slate vs synthetic guide.

Related Reading

• Why Choose a Natural Slate Roof? — the positives in full: longevity, fire, beauty and the asset value of a slate roof.
• Roofing Slate Cost: Price per m² & per Roof — what slate really costs, why cheap slate is a false economy, and how the numbers compare.
• How Long Does a Natural Slate Roof Last? — the eight factors that decide whether your roof sees its 150th birthday.
• Roofing Slate Installation Guide: Step by Step — how a proper slating job is done, and why the detail work decides the outcome.
• Slate Roof Maintenance & Care Guide — the half-hour-a-year habit that keeps a century roof boringly reliable.