Slate and clay roofing tiles are known as one of the most durable and long-lasting roofing products on the market. They have been used for centuries around the world, and original tiles still remain on buildings that are more than 400 years old.

In New Zealand, slate and clay roofing tiles are atop some of our most famous heritage buildings, churches, halls and high-end residential homes. They’re products that are known for their quality, although they do come with an initially higher price than other alternatives.

In order to choose the right roofing material for a project, Macmillan Slaters and Tilers’ Jarrod Gillespie says it’s important to understand the limitations of each available option and weigh that up with what the desired lifespan and result is.

“Longevity is the key benefit for slate and clay roofing tiles,” Jarrod says. “Both slate and clay roofing tiles are more expensive initially but these products are time tested  requiring little or no maintenance once installed, so, over time, they work out to be in cheaper than the cost of other roofing materials.”

While architects are good at explaining to clients the options for products they have, where people need to understand more is the limitations of the products they choose. “When it comes to roofing, for example, it’s crucial to know if a product is suitable for the pitch of the roof as this is the first mistake that can be made before a project is started and needs to be factored in when the plans are drawn up.”

Slate is a versatile option, suitable for everything from 90 degree cladding right down to a pitch of 20 degrees. Clay roofing tiles can be used from pitches of 18 degrees to 90 degrees. “Combined with that, careful consideration is needed to ensure the maximum rafter length for each pitch is not exceeded.” This is related to the volume of water a roof area can take in adverse conditions. “A lot of people don’t understand that roofing tiles are designed to take an even flow of water, not a concentrated flow,” explains Jarrod.

“The most common issue with roof leaks that we come across is in areas of the roof where a downpipe has been installed from an above storey onto the tiles or where boxed gutters offload on to the roof. Sometimes a separator pipe is installed to spread the flow of water, but it is inevitably in these areas where leaks occur. That’s solely because of the volume of concentrated water that is being put onto the tiles, and they aren’t designed to handle that,” says Jarrod.

It is these details that need to be carefully considered in the planning stages of a project, with full knowledge of the limitations of any product that will be used.

For Jarrod, the other issue he commonly comes across is people choosing to use artificial products such as artificial slate tiles because of the initial lower cost. These, he says, have a very limited lifespan and will generally fail within about ten years. “There are cheap, artificial products coming in from overseas even from respected areas like the UK,  but with our  high UV and unique natural environment, these products get broken down quickly and easily become brittle, even if they last longer in other areas of the world. This is a real issue as they will not pass the building code,” states Jarrod.

With genuine slate and clay roofing tiles, Jarrod says you are guaranteed a minimum lifespan of at
least 70 years. “Once a slate or clay tile roof is installed, there is no need for any maintenance over the roof’s lifespan. Essentially, slate in particular will outlast everything, including the building itself.”

Macmillan Slaters and Tilers have been working with slate and clay roofing for three generations,
operating predominantly in the high-end residential market, as well as working on heritage and historic buildings, churches and halls. “For us, it’s about ensuring quality rather than quantity. We work in a niche in the roofing market and pride ourselves on our honesty and free advice. We’re happy to turn work down if we can see our products aren’t what someone is looking for, or they aren’t suitable for the desired purpose.”

Those values relate not only to the roof tiles themselves, but looking at the roof as a whole, something Jarrod says is vital if you’re investing in a slate or clay tile roof that will last decades. In order to ensure the roof has the most durability, an important factor to consider is the quality of the flashings. “We use copper and lead flashings so that our clients know the flashings will last as long as the roof tiles to avoid maintenance issues in the future.”

Macmillan Slaters and Tilers is a family business that has been in operation for three generations. Based in Auckland since 1974 they work nationwide in New Zealand, and also maintain the country’s largest collection of obsolete slate and clay roofing tiles – a valuable resource for the country’s heritage and historic buildings that may need tiles sourced that are no longer made.
Get in touch with Macmillan Slaters and Tilers here to discuss your next roofing project.