How safe is your chimney?

Following the recent Kaikoura shakes the Brick and Blocklayers Federation (BBFNZ) have been receiving a number of queries from homeowners concerned about the safety of their chimneys. 

The risk with chimneys is that the structural integrity can, over time, become compromised.  This happens as the mortar that bonds the masonry units together becomes weathered and eroded.  With many councils and subsidies pushing towards clean air solutions there are a number of older homes with unused masonry chimneys that are generally not regularly maintained and are often simply forgotten.

“Our advice is simple” states BBFNZ CEO Melanie McIver, “If you don’t use it – consider losing it.  You are balancing around a half a ton of masonry above your head that may have become less stable with time and in a decent wind or shake, could create critical injuries or at the very least a hole in your roof at a time where building repairs are expensive and prone to time delays”. 

Chimneys should be deconstructed one masonry unit at a time, any reinforcing may need to be cut or removed and then the penetration sealed.  While not Restricted Building Work, BBFNZ urges homeowners to get a professional in to at the very least provide some advice.  While a building consent is generally not needed to remove a chimney there may be a requirement to obtain resource consent, particularly in heritage buildings

For homeowners who still use their fireplaces the advice from BBFNZ is to get them checked by a professional, especially houses built prior to the 1970’s that may have unreinforced masonry chimneys.  It is possible for eroded mortar joints to be repointed to improve durability however the best and safest option is to consider replacing the chimney with a lighter option such as a fibreglass box with brick slips.

BBFNZ is quick to highlight that while it holds concerns about the stability of old, unmaintained, masonry chimneys, study reports following the 2010/2011 Canterbury quakes show that brick veneer performed adequately with no deaths attributed to its failure.

“Brick has unfortunately received a bit of a bad reputation following media coverage of the Canterbury quakes a few years back” says Ms. McIver “What we are hoping that the public realise is that the piles of rubble that were featured in news coverage reports were predominantly from buildings constructed in the late 1800, early 1900s era.  We have improved our construction methods significantly since then with the introduction of ingenuity such as brick ties and we think that regardless, given the age of some of the buildings featured at the time in media reports, our products performed extremely well over time.  There is a reason why masonry such as brick is the preferred building product worldwide”.

Perhaps if you are after the romantic feel of a fireplace - consider placing it in your outdoor entertainment area instead.

A list of suitably skilled masons can be found on the BBFNZ website here: