Latest Research
This section of our website profiles findings we have just released from the research projects BRANZ is working on now or has just concluded. It is updated when new findings are released.
Click on a link to find out more.
- Seismic performance of brick veneer houses
- Efficacy of passive fire protection measures in NZ buildings
- Effective passive roof venting using roof panels in the event of fire
Seismic performance of brick veneer houses
BRANZ Ltd was commissioned to examine this issue. There have been a number of changes in practice in recent years, with requirements for the ties to be screw-fixed to the timber framing and with the advent of lighter bricks with vertical penetrations. At issue is whether the veneer may no longer be just a driver, but rather that it may have some lateral load-resisting capability. The complete study is intended to improve the understanding of brick veneer construction in earthquakes, in particular:
- to determine if brick veneer can be relied upon to carry seismic load or whether the building light timber framing construction should be designed to carry the entire load, and
- to identify the level of seismic damage that can be expected in modern brick veneer construction, particularly at building corners where the face-loaded and in-plane loaded veneers meet.
A series of full-scale tests of the performance of veneer systems has been carried out, with the following reports available:
- SR189 Seismic performance of brick veneer houses - phase 1 - cyclic and elemental testing of clay brick veneer construction, including slow cyclic tests of full-scale veneer specimens where the veneer clad a rectangular room which had both window and door openings.
- SR190 Seismic performance of brick veneer houses - phase 2 - shake table tests on a clay brick veneer specimen, where shake table tests were conducted on a clay brick veneer with an inertial mass to simulate roof loads. It was concluded that properly constructed brickwork using resilient ties and bricks with vertical holes could resist low earthquake loads, and collapse would be unlikely under shaking several times the ‘design event'.
Work on other aspects of these systems is underway, including a demonstration to an invited industry audience of testing of a two-storey brick veneer on Monday 6 October 2008. Further reports will emerge on these other aspects.
Efficacy of passive fire protection measures in NZ buildings
The Fire Protection Association of New Zealand (FPANZ) was commissioned to examine whether the situation found in UK which had led to the comment in the foreword to a 2007 UK publication "Research has shown that passive fire protection in many buildings is either badly installed or inadequate" was also found in New Zealand. FPANZ carried out a pilot survey of eleven buildings and found significant deficiencies with respect to what would be expected in terms of today's NZ Building Code compliance in over half. They also interviewed a number of designers, product suppliers and building officials, and found that there were concerns about some of the systems being installed. You can read their report here. FPANZ and BRANZ have convened a meeting of relevant parties, including the DBH, to review the situation and work toward solutions.
Effective passive roof venting using roof panels in the event of fire
BRANZ Ltd has investigated the appropriateness of buoyancy-driven fire venting to remove heat and smoke from fires in buildings, using passive failure and subsequent dislodgement of plastic materials to create a roof vent. The research did not address specific materials and proprietary systems, since the roof construction method, specific engineering additives to the base material, and geometry (e.g. thickness) contribute to the fire venting performance of the plastic sheeting. A summary report examines the conclusions from the earlier reports on modelling and experimental work, and proposes rules for the use of roofing panels that melt or degrade at elevated temperatures so that smoke and heat are vented under fire conditions.
Modelling report:
Experimental work report:
Summary report:
It was found that buoyancy-driven vents have a high sensitivity to ambient wind conditions, that the location of the panels is important (the larger the area of potential venting closer to the seat of the fire, the earlier openings form for venting and subsequently the earlier there is venting) and that smoke baffles play an important role in limiting the spread of hot gases across the ceiling of the compartment and aiding passive venting of hot gases and smoke. A potential test method for roof panels that might be used for fire venting was developed.
