Materials compared

Slate or Tile: Comparing Weight, Lifespan and Roof Pitch

Choosing between slate and tile is a structural decision before it is an aesthetic one, because the two load a roof differently and each has a pitch below which it stops working. Compare the options for the slate roof on service life and cost per year, then book a survey. The scope here: Natural slate · Concrete tile.

Choosing between slate and tile is a structural decision before it is an aesthetic one, because the two load a roof differently and each has a pitch below which it stops working.

What is deciding it on your roof?	What it settles
The roof's angle	Each covering has an angle below which it stops shedding water, so a shallow slope removes options entirely. The comparison starts here rather than with preference.
What the structure can carry	Concrete tile is the heaviest common covering and has loaded roofs since the 1950s. Natural slate is lighter per square metre than concrete and heavier than some clay profiles. A heavier substitution needs the structure assessed rather than assumed.
How long it has to last	Natural slate up to 100 years, clay tile around 80, concrete tile 50 to 60 — and all of them outlive their nails and battens, which is why these figures mislead when read as replacement intervals.
The figure per square metre	Slate £140–£280 supplied and fitted, the highest of the pitched coverings. Clay £110–£210. Concrete £85–£170.
Whether the covering comes back	Slate is routinely relaid and returns to the roof. Concrete tile rarely is, so a lifetime cost comparison that ignores reuse is wrong.
A conservation designation	It frequently forces natural slate regardless of preference.

Slate is sized and gauged to pitch, with smaller units on shallower slopes. This page does not recommend a covering. It recommends surveying the structure that has to carry one.

3 related pages cover this in more depth: slate roof installation and repair, tiled roof installation and repair and Minimum Roof Pitch by Covering Type.

Which lasts longer, slate or tile?

Natural slate lasts longest, reaching a century. Clay tile reaches around eighty years and concrete around fifty to sixty. All three outlive their original fixings and battens, which is what actually determines when a roof needs work.

Natural slate is lighter per square metre than concrete tile, heavier than some clay profiles. The concrete tile has a weight of the heaviest common covering, and the one that has loaded roofs since the 1950s.

Does the roof structure affect the choice?

Yes. Coverings differ substantially in weight per square metre, and the rafters and walls were sized for what was originally laid. Substituting a heavier covering requires the structure to be assessed rather than assumed adequate.

The service life of the clay tile is around 80 years, holding colour throughout; the concrete tile lasts 50 to 60 years, fading and roughening with age. Each covering has an angle below which it stops shedding water.

Does the roof pitch limit your options?

Yes. Every covering has a minimum pitch below which it stops shedding water reliably. A shallow slope removes some options entirely, so the roof's angle is established before any preference is discussed.

Swapping to a heavier covering requires the structure to be checked. Slate is sized and gauged to pitch, with smaller units on shallower slopes.

Slate £140–£280 supplied and fitted, the highest of the pitched coverings

Which costs more over its life?

Slate costs most to install and least over its life, partly because most of the stone returns to the roof in a future relay. Concrete tile is cheapest to fit and is rarely reused when it comes off.

Designation frequently forces natural slate regardless of preference.

Covering weight loads the roof structure which must be checked before substitution.

Can you change from one to the other?

Sometimes. Moving to a lighter covering is usually straightforward. Moving to a heavier one requires structural checking, and a conservation designation or planning condition can rule out the change entirely regardless of structure.

Each covering has a minimum pitch below which it stops shedding water.
Slate is routinely relaid where concrete tile is not.
A conservation designation overrides a preference on visible elevations.

Sometimes the choice has already been made for you.

When designation decides it

Changing covering type changes the load on rafters and walls, and a heavier substitution needs the structure assessed rather than assumed. Slate returns to the roof in a relay; concrete tile does not, so lifetime cost comparisons that ignore reuse are wrong.

Getting the structure assessed

A shallow slope removes options entirely, so the comparison starts with the roof's angle, not the owner's preference. Both coverings outlive their nails and battens, which is why service life figures mislead when read as replacement intervals.

Gauge, and 5 more

gauge
headlap
minimum pitch
structural capacity
strip and relay
unit weight

Book a free roof survey

Or call 07446 375079.