Chimneys can collapse in an earthquake
When the ground shakes, older unreinforced brick and concrete masonry chimneys can cause serious damage to homes and harm to people. Chimneys can be the heaviest part of a timber-framed house, and can weigh hundreds of kilos. That weight may cause them topple or collapse through the roof or fall outwards and damage your property, or your neighbour’s.
We know that thousands of hazardous chimneys exist around New Zealand, with many homeowners unaware of their danger. If your home has a chimney, check to see if it might be at risk. You can then take steps to make it safer.
“The chimney had been on the external wall right next to our baby’s cot. It had fallen alongside the house and ripped off part of the roof, narrowly missing our baby’s room.
If it had fallen a different way, it would’ve crushed our son, the other way, it would have smashed the neighbour’s car.”
- Emily from Wellington, talking about her experience of the 2016 Kaikoura earthquake.
Assess the risk of your chimney
Your first job is to determine whether your chimney is at risk of collapse. Older brick and unreinforced masonry chimneys are the most at risk.
Chimneys built before 1970
Chimneys of this age 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
Chimneys built since 1985 should have a reinforced concrete flue within the brickwork and be tied to the house framing to help prevent collapse. A quick inspection from a licensed building practitioner should be able to confirm if your chimney is reinforced or not.
You can check a property’s LIM report or property file for more information on the age of a home. No matter its age, if your chimney is showing signs of damage or wear and tear, contact a licensed building practitioner urgently.
Check your chimney for signs of damage
Look for signs that your chimney might be unsafe. Common signs of damage include:
- cracks in the brick or mortar
- a lean or twist in the chimney structure
- loose, missing or broken bricks or masonry.
You should also check whether the chimney is connected to the house with steel strapping at each storey and to the roof.
If you notice any of these warning signs, you should contact a licensed building practitioner. They'll be able to properly inspect your chimney and give you advice on what actions you should take.
Dealing with a risky chimney
Your best course of action will depend on whether your chimney is still in use or not. If you no longer use your chimney, removal is the safest option.
Remove the entire chimney
If you have a fireplace that's no longer in use, completely removing all elements of the chimney eliminates the risk that it will cause damage or injuries in an earthquake. This includes removing the section above the roofline, to the bricks inside the walls down the floor level of your home.
Removing all the components of the chimney is the safest option, but be aware that it’s a significant piece of work and the most expensive option.
Installing a faux chimney can be an alternative if your council requires you to retain the visual character of your home, or if you just like it. Faux chimneys replicate the original chimney’s appearance while reducing weight and freeing up space inside the home.
Replace or remove chimney above the roofline
The most hazardous part of the chimney is the section that sits above the roofline. Removing just that part can be a good option if your chimney is still in use, or if your budget doesn’t allow you to tackle the whole job right now.
If your fireplace is still in use, you can replace this part above the roofline with a lightweight metal flue. The new flue can be installed at the same time as a solid fuel heater without needing to replace the existing firebox.
Lightweight flues can be made to look like a brick flue. This style might be a good option for character or heritage homes, mimicking the original brickwork while also reducing weight.
If your fireplace is no longer in use, removing this structure entirely and not replacing it is a great option. This option is usually cheaper and quicker than removing the entire chimney.
One homeowner's chimney removal journey
Homeowner Amber talks about the process to remove her hazardous chimney to the roofline – removing the weight off her roof, and off her mind.
Strengthen existing elements
If removing the chimney is not possible right away, you can reduce the risk by adding:
- plywood bracing into the roof space to stop bricks and masonry from falling into your home
- restraints or straps that anchor the chimney and secure it to the home (the size of the chimney will determine what strapping you need).
Talk to a licensed building professional about the best option for your home.