Choosing roof tiles: concrete or clay?

The roof covering accounts for a significant cost on a self-build and will dictate the aesthetic for decades. Emily Brooks explores the main differences between the two most popular choices of material
Emily Brooks
by Emily Brooks
17th May 2016

While concrete roof tiles are undeniably the choice of the mass market, many people opt for clay when it comes to putting a roof over their heads.

Self builders tend to be a discerning bunch who have a slightly different set of benchmarks, often valuing craftsmanship more highly, which sometimes tips the balance in favour of clay.

But with such a large variety of styles and profiles available in concrete, as well as a keener price tag, there’s a good argument for both. Here are the main differences.

Read more:  Choosing roof tiles for renovation projects

Aesthetic appeal

“Clay has a proven history of longevity, and has been used for years as a material for building products,” says Richard Bishop, category marketing manager for roofing at Wienerberger. “On the other hand, concrete can offer a clean and smooth finish due to the aggregate used in the mix.

However, this process creates a ‘swiss cheese’ effect that’s visible when a concrete unit is viewed from its leading edge. It’s not present with clay versions as the material is cut.”

Over and above this, the rich, natural hues of clay tiles, and the subtle colour variations between them, are the principal reasons why this covering is specified ahead of concrete.

“The fact that no two clay units are identical makes them good for mixing, and that organically blended finish is very pleasing,” says Dana Patrick-Smith from Dreadnought.

brick home with concrete roof tiles

Rustic clay tiles in Dark Heather, used on a Derby self-build, Dreadnought

“If anything, clay improves with age; the colours mellow and it becomes more characterful.” Attractive blends are essential on period homes where they need to mimic the manufacturing methods of old, but a solid hue could be better for crisp modern designs – and this is where concrete can come into its own.

Concrete is chameleon-like, able to mimic the colour of clay as well as other materials, such as slate. However, it tends to have an artificial look that’s definitely noticeable when placed side-by-side with clay, plus it will fade to grey over time.

Whichever material you opt for, a replaced area of tiling will never perfectly match the old original roof – but the contrast can be starker with faded concrete.

Planning constraints & authenticity

“A lot of self-builders come to us because of planning constraints,” says David Osborn, director at Lifestiles. “In conservation areas and on listed buildings the planners often prefer you to use clay.” In some areas of the country, especially the south east, this material is intrinsically associated with the vernacular style.

If historical authenticity is critical, then only a handmade product will do – and achieving suitably subtle imperfections in texture, colour and size is certainly not possible with concrete.

“Handmade clay products support a traditional sector of the market and offer a unique finish you can’t achieve with a machine, although they are not right for every project,” says Richard Bishop.

Some manufacturers offer a halfway house between handmade and machined tiles – usually referred to as hand-crafted or hand-finished products.

“A genuine handmade tile is pressed into a mould, whereas a hand-finished one is extruded and then given a sandfaced effect that replicates the effect, before it goes into the kiln,” explains Aaron McLaughlin of Heritage Clay Tiles. Beautifully crafted as they are, handmade products cost around 50% more than mass produced ones.

Characterful handmade roof tiles

Handmade clay tiles by Tutor Roof Tiles

Tudor’s range of traditional handmade clay peg and plain roof tiles have a natural aesthetic appeal that will make your roof unique.

Crafted by hand using skills that have hardly changed over the ages, and now fired in a kiln using the latest technology, our authentic sandfaced tiles have a distinctive ‘old world’ character combined with exceptional durability.

The tiles are much sought after because, being individually made, no two tiles are ever exactly the same. Blended together they create a striking roofscape that will add individuality, distinction, and value to your home. Furthermore, they weather and mature with the passage of time, becoming even more attractive!

Made from the finest English clay, Tudor offer a variety of natural mellow colours, double or single camber and in standard or bespoke sizes to suit your particular project and its surrounding area.

Handmade roof tiles

Longevity & maintenance

“There’s no real performance gap between concrete and clay – they’re both going to keep the water out and last a long time – so it really comes down to aesthetics,” says David Osborn from Lifestiles.

Manufacturers typically guarantee products for 30 years, but their full life cycle could easily be double that, depending on what kind of conditions the roof has been exposed to. It’s far more likely that what’s underneath (the battens and underlay) will fail before the tiles do.

Clay is more porous than concrete, and moss is more likely to grow on damp clay (though you will still get some moss and lichen on concrete).

This is not generally thought of as a problem unless it’s blocking gutters, and many people like the aesthetic of a moss-covered roof.

Clay tiles are more subject to damage in cold weather due to the cycle of freezing and thawing (hence they’re more prevalent in the south, where average temperatures are warmer). However, all products are tested to rigorous standards.

Quality control

So what benchmarks are there to help you gauge quality? Dana at Dreadnought suggests asking how many frost cycles a product has been tested to (its tiles are frozen and thawed 400 times).

She also points out that Dreadnought’s clay tiles only get their colour from the firing process (some manufacturers spray the shade on afterwards – if it’s a different hue front and back, the colour didn’t come from the kiln).

This can make a subtle but important difference to the overall look. Aaron at Heritage Clay Tiles has a further tip for self-builders and renovators: “If you tap on a clay tile and it sounds dull, like knocking on wood, then it’s been badly made and badly fired; but if it has a ring to it, that’s usually a sign of a good quality product.”

If you’re going for concrete tiles, for best results make sure they have been through-coloured rather than treated with something that has been applied to the surface. If your roof can take it, opt for heavy units, which should be less prone to breakage than lightweight options.

Cost considerations

You can expect to pay around 20% less for a concrete tile as opposed to a standard machine-made clay version. This may seem like a tempting saving, but spread that cost over the lifetime of the roof (50 years plus) and the difference might become more bearable.

As Dana points out, “your roof isn’t going to be replaced or upgraded any time soon” – so get it right first time.

Photo (top): Bespoke clay tiles mix, Lifestiles

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