BRANZ Workshop Programme
TUESDAY 2 November 2021 | 10am to 1pm
Please note this is a seperately bookable event and, while registration to WoodWorks 2021 is recommended, this is not required to attend. To register for WoodWorks 2021, visit the registration section on the main event page.
Most countries have been revisiting their external fire spread building controls following a series of high consequence external fires internationally, and New Zealand is no exception. Residential construction densification, carbon targets and rising building costs all create pressures for managing external fire spread appropriately.
In November 2020, MBIE proposed some changes to external fire spread controls in the Building Code compliance documents. Concerns were raised by some that these changes would result in a “timber ban”. This section of the workshop will discuss findings from BRANZ research into external fire spread controls, key factors driving external fire spread management and what changes in the future might mean for the use of timber in buildings.
Partial Timber Linings: MBIE has previously (2017 consultation) indicated that they would like to de-quantify building code clauses where possible. Clause C3.4 currently restricts the application of surface linings by requiring specific Group Numbers for lining materials in particular areas of buildings, depending upon usage. These group numbers are based upon having the whole room lined with the material being tested.
With the current drive for more sustainable construction, timber is seen as a good material from a carbon perspective. However, untreated wood will only normally achieve a Group 3, which might be overly restrictive. This work has been looking at methods for being able to quantify the risk posed by having partial timber linings in areas that would normally require a Group
Mass Timber: BRANZ fire researchers have been working on a mass-timber pyrolysis module in B-Risk. This includes thermal performance of adhesives and the ability for a fire to re-grow in the event of lamella failure exposing fresh fuel. This can result in much extended burn-out times. Also, exposed steel in mass timber connections, has been shown to be a potential problem in fire.
Although the wood (beam and column) may not reduce in cross-section enough to cause structural failure, evidence from recent tests shows that the joint itself may fail significantly earlier. How do we design and build these mass-timber structures with adequate protection from fire, while still providing adequate seismic performance?
New Zealand has an urgent need for quality housing that can be built quickly and affordably. In response, prefabricated building systems are becoming more widespread in New Zealand as recognition grows of their potential to provide resilient, high quality buildings. One example of this is the use of structural insulated panels (SIPs) having timber-based skins. SIPs are being considered more often for a wide range of structural applications including residential and commercial construction and as an option for mid-rise buildings.
The detailing and performance of SIP systems can be significantly different to other commonly used building systems. This means that investigation is required to ensure that SIPs-based buildings will perform adequately when subjected to the environmental conditions and natural hazards encountered in New Zealand. To do this, BRANZ has undertaken a research project to investigate the durability characteristics, earthquake resilience and fire performance of SIPs.
This presentation will briefly discuss the findings of these three workstreams and put them in the context of buildings constructed in New Zealand using SIPs. Details on existing New Zealand SIP buildings will be presented as case studies to show how these systems can be designed as energy efficient and quick to erect buildings that have the diversity of form expected from highly prefabricated buildings using modern manufacturing methods.
A presentation of a selection of construction methodologies that meet various R-Values in the current H1 consultation document. The pros and cons of various solutions will be discussed, including highlighting assembly types that could bring significant risk of moisture accumulation. Guidance will be given on aspects to look out for, as well as what constitutes risk.
In addition, workflow to properly assess the risk of moisture accumulation using WUFI will also be presented, which is important as a lowered heat flow reduces drying capacity of the assembly. This will be based on international best practice with additions from BRANZ experimental work in our capacity as a collaboration partners with the Fraunhofer Institute For Building Physics (the creators of WUFI). Properly applied hygrothermal modelling can give a robust assessment of risk and selections of the various materials in each assembly, guiding good design.
Pinus radiata timber is used as both an untreated and treated construction material in a range of climatic and environmental conditions. This research is studying the durability and resilience of Pinus radiata following exposure in 8 natural exposure locations. The research has involved the collection of data relating to long-term moisture dynamics, chemical degradation (diffuse reflectance infrared fourier transform spectroscopy (DRIFTS), colour changes), biological growth and corrosion of fasteners within timber.
This presentation will cover the results of the first three years of exposure and will demonstrate the significant variations that have already occurred in initially like-for-like samples. Variations are most clearly observed in materials exposed to a geothermal environment.
In the longer term, data gathered during this project will be used to inform models for correct material selection for specific climates, geographies and inferred durability requirements. The research team will feed the data into the further development of corrosion post-process model systems and develop clear guidance for designers on material selection, especially when considering the use of timber. This will become increasingly relevant as countries move towards low carbon economies and the use of timber as a core building material increases.
Wood products have been used in construction for millennia. Over time, the art of taking smaller pieces of wooden material and joining them together has greatly improved the usability of wood. Engineered wood can often now be used as a sustainable alternative to steel and concrete in modern construction.
Building with wood products from sustainably managed forests carries significant environmental benefits. The environment and the health of the planet is an issue that has seen a meteoric rise in awareness and concern by many. The ability of a growing tree to absorb carbon dioxide and sequester the carbon is beneficial in the role of combating rising carbon dioxide levels. The appropriate and sustainable (including replanting) processing of trees into construction materials locks up the sequestered carbon. However, once in situ, wood products can be susceptible to degrade over time, particularly by biological organisms such as fungi and insects.
In order to store the carbon in wood products for the maximum time possible, the author argues that the appropriate use of suitable biocides is desirable in many situations. The use of biocides to preserve engineered wood products and the benefits that can be attained are discussed. Also described are examples of effective biocide use in engineered wood products.