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Chimneys remain common hazards on NZ homes

Fuseworks Media
Fuseworks Media

Tens of thousands of chimneys have been damaged or collapsed in previous New Zealand earthquakes.

On this day in 1855, a 8.2 Magnitude earthquake rocked the Wairarapa and Greater Wellington regions, with thousands of chimneys collapsing or causing damage to many homes at the time. Sadly, one of the few fatalities from this event was attributed to the collapse of a brick chimney in the room in which he was sitting.

So why are hazardous chimneys still so common on homes across the country? Engineering Manager at the Earthquake Commission, Martin Connell, says making your home safer before a disaster is a key step for any homeowner.

"The fact is that pretty much every major earthquake over the past 170 years has shown that chimneys pose a significant risk to the safety of people and the strength of our homes.

"Brick and masonry chimneys may crack, shift or collapse in an earthquake, causing damage to people and property. They can also topple or collapse through the roof or fall outwards damaging other parts of your property - or your neighbours’. These chimneys can weight hundreds of kilos, so they’re really not something you want coming down during a quake."

As a result of the Canterbury earthquakes of 2010-11, numerous insurance claims were made because of unreinforced chimneys falling and causing damage to properties across the area.

Brick and concrete masonry chimneys built before the 1970s pose the greatest risk as they’re less likely to have extra internal reinforcement. Older chimneys are also more likely to have deterioration of the mortar that helps hold them together.

Brick chimneys built after 1985 should have a reinforced concrete flue within the brickwork and be tied to the house framing to prevent collapse. But no matter its age, if your chimney is showing any signs of damage or deterioration then get a Licensed Building Practitioner to check it out urgently.

Things to look for include chimneys that are leaning or twisting and loose masonry or bricks, or cracking.

"There are plenty of things people can do to make a hazardous chimney safer," Martin says.

He explains that it might be worth thinking about how often a chimney is used and whether it’s time to replace it or remove it completely.

Martin acknowledges that effort and/or cost are the main barriers for making chimneys safer, but asks people to consider the following:

Removing all hazardous elements

The safest option for a hazardous chimney is to remove it from the top all the wall down to the floor level of the home. This work is often extensive but means that the risk posed by any collapse of brick or concrete is removed completely.

Removing or replacing the chimney above the roofline

The most hazardous part of the chimney is that which sits above the roofline, so the next best option is to remove or replace this part of the structure. If the chimney is still in use this piece of the chimney can be replaced by a lighter weight metal flue.

Strengthening existing elements

If you can’t remove or replace your hazardous chimney right now, there are other steps you can take to reduce your risk of injury or damage. Restraints can be added to the chimney to secure it at important junctures with the home and plywood bracing can be added into the roof space that will help stop falling bricks and masonry ending up in the living area.

One thing to consider is that, depending on the chimney’s construction, a building consent might be needed to remove it and will need a licensed building practitioner to do the work.

"Some safety improvement work with chimneys can be completed without council consent. But it’s important to check with your local council’s regulations and make sure that any work is still completed to the standard of the Building Code."

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