| Why remove brick (unreinforced masonry) chimneys?
Unreinforced masonry (URM) buildings have been shown countless times to perform very poorly in earthquakes. This became apparent especially after the 1931 Napier earthquake in New Zealand. However the construction of unreinforced masonry buildings in New Zealand remained in-use till the late 1940s, and was finally outlawed in 1965. There are, therefore still a number of existing unreinforced masonry buildings today.
Buildings which are seismically at risk can either be demolished and a new structure built in its place, or else the original structure can be retrofitted to ensure it aligns with today's current performance criteria. As unreinforced masonry was a very common building material in early New Zealand (particularly 1860 - 1930), a significant proportion of the URM building stock falls into the category of 'heritage architecture'. Moreover, many of these buildings are protected by The Historic Places Trust of New Zealand, and may not be demolished or changed externally, so retrofitting and strengthening the building is the only option.
Before a building can be appropriately retrofitted, it is first of all necessary to provide an accurate assessment of the structure's inherent capacity to withstand an earthquake, and what parts in particular are most at risk.
The Seismic Assessment of Existing Buildings Guidelines provides a technical basis for engineers to carry out seismic assessments of existing buildings within New Zealand. If a seismic assessment is conducted and parts or all of the building is not considered to be strong and safe enough to withstand earthquakes, then action must be taken to remedy this.
In order to maintain heritage architecture, whilst improving the strength and safety of commercial buildings and houses, areas of unreinforced masonry must be strengthened or removed and replaced with a more lightweight and safer material.
Unreinforced masonry chimneys perform very badly in earthquakes and pose a significant risk to the safety of people who are in and around the building where the chimney is located. It’s because of this that we specialise in the removal and replacement of brick chimneys across New Zealand.