Chimney Removal, Unreinforced Masonry and Parapets: What to Check First

Why Old Chimneys and Parapets Are a Weak Point

If your house was built before the 1970s, there's a good chance it has an unreinforced brick, stone or concrete chimney. In an earthquake, these are some of the first things to fail: they can shear off at the roofline and come straight down through the ceiling, or topple onto whatever is below, including the street or a neighbour's property. Chimneys built after 1990 are a different story — they generally have a reinforced concrete flue tied back into the house framing, and a lightweight metal flue carries very little risk at all.

Parapets on older commercial and multi-unit masonry buildings carry a similar risk. Because they sit above the roofline with little lateral support, they can shake loose and fall onto the footpath below, which is why councils treat securing them as a priority.

Warning Signs Worth Acting On

• Heavy brick or older concrete construction with no visible reinforcing
• Cracking, or loose and crumbling masonry or plaster
• A chimney that visibly leans or has twisted away from the roofline

Any of these point to a chimney that needs a professional look, not a "wait and see" approach — cracked masonry around a working fireplace is also a fire risk, not just a structural one.

Can You Remove a Chimney Without a Building Consent?

Removing an unreinforced chimney is often exempt building work, but only when it clearly meets a specific set of conditions. As a general guide (your council's own rules may vary, so always confirm before starting):

• It's an unreinforced brick, stone or concrete chimney
• The building is no more than three storeys
• Removal won't damage or weaken the building's primary structure
• It isn't a chimney stack shared between two semi-detached buildings
• It doesn't support an upper floor or part of the roof structure

If any of these don't apply, you'll need a building consent before work starts — and the work still has to meet the Building Code and use acceptable trade practices either way, including making good any holes left in the roof, ceiling or internal linings and keeping the building weathertight.

The Catch With Partial Removal

If a chimney has already been flagged as earthquake-prone, simply removing the risky top section doesn't automatically clear that status. A chartered professional engineer (CPEng) typically needs to assess and certify what remains before the earthquake-prone classification can be lifted — so it pays to get engineering advice before you start, not after.

Securing a Parapet or Masonry Facade

Work to secure a parapet or unreinforced masonry facade can also avoid needing a building consent, but again only under defined conditions: a CPEng designs the work or reviews the design, the work follows that design, heritage values are considered as far as reasonably practicable, and the council is notified at least three days before work begins. Any further strengthening work beyond securing the parapet will usually need its own consent.

Get Advice Before You Start

Because the exemption conditions are specific and the consequences of getting it wrong include a collapsed chimney or an unresolved earthquake-prone rating, it's worth talking to your council and a structural engineer before any work begins — even for what looks like a simple removal job.

If you're weighing up whether to remove, strengthen or simply monitor an old chimney, parapet or masonry wall, get in touch with Fil Engineers — we're happy to help you work out the safest and most practical option for your building.

Sources

• National Hazards Commission – Chimneys
• Wellington City Council – Remove a chimney
• Building Performance (MBIE) – Unreinforced masonry: get advice from a building professional
• Building Performance (MBIE) – Exempt building work: removal of a building element

This article is general information only and isn't a substitute for site-specific engineering advice. Consent exemption conditions can vary by council — always confirm requirements with your local council and a qualified engineer before starting work.