John Jamison – Technical and Development Manager
A residential building needs to deliver so much. It is where we live, where we sleep and increasingly where we work – and it needs to be resilient to ensure we can do all of this safely and sustainably.
Buildings are constructed from many different building products, but rely on all these products working together as a system – or rather a collection of systems. Of course, we can’t just hope these systems work. Building designers and Building Consent Authorities (BCAs) need to be assured these systems can meet the specified performance requirements, so there must be evidence to support any performance claims made.
Within the New Zealand building regulatory framework, this can be achieved through a design following an Acceptable Solution, a system having a CodeMark certification, or through the system having a third-party assessment, such as a BRANZ Appraisal.
Systems greater than the sum of their parts
Each individual component of a home incorporates a myriad of design components. A lightweight wall, for example, may have its own acoustic, thermal, fire, wet area or structural performance requirements (or combinations of all five). The wall will typically be made up of a wall lining, insulating element if it is an external wall, fixings for the wall lining and the framing members, wet area requirements or treatments, and of course the wall framing members themselves.
How all these individual components are selected and assembled is what delivers the desired overall performance – and so it can be very difficult for a designer or a BCA to determine whether an arbitrary group of individual products delivers the desired performance without referring to a specific system’s demonstrated performance.
Efficiency in systems design
The performance requirements of the NZ Building Code, as it relates to structural stability for light timber-framed residential construction (Clause B1), are deemed to be met if the structural design is compliant with NZS3604. Within NZS3604, Bracing Units (BU) are used to describe the wind and seismic demand of these light timber framed structures.
We have developed GIB® wall systems that incorporate the use of plasterboard in combination with other components to deliver BU performance, allowing designers to use the GIB® wall systems as part of the structural bracing design. In using the performance characteristics of the plasterboard lining that would be used anyway, this precludes the need for other construction components traditionally required for bracing, thereby integrating efficiency and cost-efficiency into the wall system.
Minimum standards may not apply
When it comes to plasterboard, not all products are created equally. There is a standard – AS/NZS2588 – that sets a base level of performance that a plasterboard product should meet. However, under an efficient, performance-based building control system, products may need to be designed and produced to perform well above this base level to deliver the desired overall performance the system requires.
In the case of wall lining systems, if our specifically-designed plasterboard product were to be substituted with a product that just conformed to the base standard requirement, the system’s performance may not be met.
Modern buildings are more than just an assembly of products. Rather they are made greater than the sum of their parts by leveraging synergies between them.
The intent of New Zealand’s performance-based Building Code is to drive innovation – and we believe that by providing performance systems options that eliminate the need for additional products we can increase efficiency and value for the customer and help create healthy, sustainable homes for current and future generations.
For more information see: https://www.gib.co.nz/systems.