Concrete or clay: which have you got?
Concrete tiles have their colour as a coating on the surface. Monier, a tile maker, says that coat fades over time. Resene adds that concrete tiles turn fairly porous as they weather and readily support moss and mould.
Clay (terracotta) tiles hold their colour well: Monier warrants its terracotta colour for 30 years, says terracotta generally shouldn't be painted, and says it's not unusual for it to give more than a century of service. Level, BRANZ's homeowner site, gives clay tiles an expected durability of 50+ years with correct installation and upkeep.
If a broken piece turns up in the garden, its edge is a clue: concrete usually shows grey under its coloured coat, while unglazed terracotta is much the same colour right through.
What usually goes wrong
Cracked and broken tiles. Tiles crack under feet. Consumer NZ warns clay and concrete tiles can be damaged when walked on, and Monier's warranty excludes foot-traffic damage.
Ridge mortar. Monier says the bedding (the mortar that holds the ridge caps on) and the pointing (the top layer sealing the joints) crack and loosen with age, and that repairs should use modern flexible compounds applied by a roofing professional.
Moss and lichen. Both grow on damp, weathered tiles, hold moisture and wash debris into the spouting (gutters). Our moss and lichen guide covers treatment.
Loose tiles after an earthquake. BRANZ found that in Christchurch's hill suburbs, concrete and clay tiles were often knocked off their battens because they weren't tied down or the ties had corroded. The Natural Hazards Commission notes a single tile can weigh up to 4.5 kg, and suggests either swapping heavy tiles for metal or checking the fixings aren't loose, rusted or broken.
How a roofer repairs a tile roof
Cracked tiles are swapped for matching ones. Older profiles can be hard to match, so ask whether the replacements will be new or salvaged. Level says clay tiles can be re-used if they come off carefully, but to expect losses of up to 30%.
Ridge caps are re-bedded or re-pointed, or both, with a flexible compound. Valleys and flashings around chimneys and walls get checked and replaced if rusted. On a quake-prone or windy site, a good roofer also checks the tile fixings. E2/AS1 allows stainless steel tile fixings in any exposure zone but hot-dip galvanised ones only in Zones B and C, so salt air matters.
Cleaning should be gentle. Monier strongly advises against pressure washers on roofs and excludes damage from cleaning with unsuitable chemicals or pressure from its warranty.
Is painting tiles worth it?
On concrete, only if the look matters to you. Resene sees no reason to paint concrete tiles other than appearance, and often suggests a concrete stain instead. Monier says a repaint needs redoing every five years or so and doesn't improve waterproofing. Clay is best left unpainted. Thinking about it anyway? Read painting a tile roof first.
When a re-roof makes more sense
When tiles are crumbling or cracking right across the roof, repairs stop adding up, and that's when lighter roofing is worth a look. MBIE's consent exemptions guidance gives replacing an old clay tile roof with profiled metal, such as longrun or pressed metal tiles, in the same position as work that doesn't need consent, though higher uplift forces on lighter roofing must be considered. Going the other way, from iron to concrete tiles, does need consent because of the extra weight.
NZ Steel, which makes steel roofing, says experts strongly recommended lightweight metal over heavy tiles after the Christchurch earthquakes. Weigh that with your roofer's view of your house, and see our guides to restoring or re-roofing and consent for a re-roof.
What a good tile roof quote covers
- How many tiles are being replaced, and whether the replacements are new, matched or salvaged
- Ridge work: re-bedding, re-pointing or both, and the compound used
- How the roof will be cleaned, with no high-pressure water-blasting of the tiles
- Whether tile fixings and ties will be checked, and replaced if rusted
- Any paint or stain by product name, and the reason it's recommended
- Scaffolding or edge protection for the job
- A quote (a firm price) rather than an estimate, with the workmanship warranty in writing
What you can do, and what needs a roofer
You can
- Look from the ground for slipped or missing tiles and gaps along the ridge
- Book a roof and spouting check at least once a year, twice if trees overhang, as Monier suggests
- Have overhanging branches cut back
- After an earthquake or a big blow, check the garden and spouting for broken tile pieces
Leave to a roofer
- Walking on the tiles, even just to look: Monier advises homeowners not to clean their own tiles because of falls and breakage
- Swapping tiles and ridge work
- Moss treatment and cleaning on the roof
- Checking tie-downs, valleys and flashings
What we'd do with a tired tile roof
If the tiles are mostly whole, we'd spend on the ridge, the broken tiles and a gentle clean, and skip the paint unless the look really matters to you. Ask for photos of the ridge and any cracked tiles so you can see what you're paying for. In a hilly or quake-prone suburb, have the roofer check the tile fixings while the scaffold is up. If you'd like someone to look, we'll pass your job to one checked local roofer.
Want a roofer to take a look?
Tell us the job and your postcode. We match it with a Find My Roofer certified roofer who specialises in that kind of work, and they call you to quote. Your number goes to them alone.