Slate vs Tile Roofing: What's the Difference?

What each covering actually is

Slate means either natural slate — quarried stone, split into thin units — or fibre cement slate, a manufactured flat unit that resembles it. Tiles are manufactured units, most commonly concrete or clay, available in flat, interlocking and profiled forms.

That difference in manufacture drives most of the practical differences that follow: variation and unit size on the slate side, consistency and coverage on the tile side.

Appearance and property character

Natural slate has variation in tone and texture, and the small unit size gives a fine, regular appearance that suits period and traditional properties. Fibre cement slate gives a more uniform version of the same look.

Tiles range from plain flat tiles that look similar to slate at a distance, through to strongly profiled pantile-style tiles. On many Dublin streets the prevailing covering is a genuine consideration: a roof that fits the terrace usually looks better and causes fewer questions in conservation areas.

Weight and roof structure

Coverings differ in weight, and the roof structure was designed for whatever was originally on it. Changing from a lighter covering to a heavier one is not simply a matter of preference — the rafters, purlins and supports have to be able to carry it.

Where a change of covering type is being considered, the structure needs to be assessed, and in some cases that means input from a structural engineer. We will flag it rather than assume.

Pitch, exposure and weather

Every covering has a minimum pitch below which it should not be used, and those minimums differ between slate, plain tile and interlocking tile. A low-pitched roof therefore narrows the options.

Exposure matters too. On coastal and elevated sites around Dublin, wind uplift and driving rain drive decisions about fixing specification, and both slate and tile can be specified appropriately for exposed positions.

Repairs and maintenance

Slates are individually fixed, so a single damaged slate can normally be replaced neatly. On older roofs, the practical issue is matching: sourcing slates that match an existing weathered roof takes more effort than an off-the-shelf tile.

Interlocking tiles are quick to replace where the profile is still manufactured, and awkward where it has been discontinued. Either way, the most common repairs on both are at the details — valleys, flashings, ridges and verges — rather than in the field of the roof. See slate and tile repairs.

Durability and lifespan

We are not going to publish fixed lifespan figures, because they depend on the quality of the specific product, the exposure of the site, the fixing specification and the detailing. A well-laid roof of either type, properly detailed, lasts a long time; a poorly detailed roof of either type does not.

In practice, what usually brings a roof to the end of its life in Ireland is fixing fatigue and perished underlay rather than the covering itself wearing out.

Cost considerations

Material cost varies by type and quality, and labour varies with unit size and detailing. Rather than claiming one is always cheaper, the useful step is to price the two options for your actual roof, which we are happy to do side by side. See the new roof cost guide.

How to decide

Start with what the roof can take and what the pitch allows, then consider the character of the property and the street, then compare prices for the realistic options. An inspection establishes the first of those. See roof inspections, new roofs and slate roof replacement.