Should chimneys be removed from Kiwi homes?
In the wake of the recent earthquakes, awareness is rising over the risks chimneys pose to New Zealand housing.
The 2010 and 2011 Christchurch earthquakes caused significant damage to Strowan House, the 123-year-old homestead at St Andrew's College. This was largely due to the collapse of its seven large brick chimneys.
According to St Andrew's College, the homestead required extensive refurbishments to bring it up to today's engineering and safety standards.
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Collapsing chimneys caused extensive damage to the roof of Strowan House. Photo: St Andrew's College
The chief executive of Brick and Blocklayers Federation of New Zealand, Melanie McIver says one of the biggest dangers chimneys pose is their potential to collapse in an earthquake.
"At the end of the day a chimney is a chunk of masonry sitting on top of your house, and if it isn't properly reinforced, it could fall," she says.
McIver says many chimneys built before the 1960s were made of unreinforced masonry. This means the structures were not reinforced with timber or steel, increasing the likelihood of a chimney collapse in the event of a natural disaster.
After seeing the damage caused by unreinforced chimneys in the Christchurch earthquakes, Nick Williams from Quakesafe Building Solutions has been committed to increasing the safety of buildings through his company's replica chimneys.
Quakesafe Building Solutions produces replica chimneys made entirely from fibreglass. These are fully engineered and compliant with New Zealand building codes.
"They're a safe, lightweight product, which can be customised to look like your original chimney," Williams says. "The chimneys are especially popular among homeowners who wish to preserve the original character of their heritage home. They provide an alternative to heavy masonry builds."
In order to ensure the future stability of Strowan House's refurbished chimney, the school rebuilt it using a lightweight replica, with the structure's original bricks removed and cut down to 20mm slices that were then glued onto the fibreglass core.
"(Five) years on from the earthquakes, the seismic strengthening and repair work done on Strowan house has not only made the building more resilient, but also restored it to its original glory," says a St Andrew's College spokesperson.
"While it is sad that much of the original heritage components of the building have been replaced with replicas, Strowan house remains an extremely significant building and there is no question of its sentimental or heritage value."
Chief executive of the Insurance Council, Tim Grafton, acknowledges quake-damaged chimneys are an issue, but says it is too early to tell how big a problem they posed for the Kaikoura earthquake.
"Chimneys are often damaged during strong earthquakes and the percentages vary from event to event," he says.
"If homeowners living in earthquake-prone areas are concerned about the safety of chimneys, or any other part of their home, they should get them checked. People shouldn't rush to remove them though without first getting professional advice."
According to McIver, removing a chimney generally requires no building consent, as long as the building in question is less than three storeys. However, she also recommends that anyone wanting to remove their chimney consult a licensed bricklayer.
"It isn't a DIY job. I've seen some horror cases of people trying to take down their chimney by themselves and it almost always ends badly."
Following the Kaikoura quake, Williams hopes homeowners will become more aware of the importance of ensuring they have a safe chimney.
"Safety is vital. People need to be cautious about chimneys and be more aware of the dangers an old, unstable structure can present," Williams says.
"It's important to communicate to people that if you don't have your older chimneys checked or replaced, you could be putting yourself and your family at risk."