We apologise in advance for this article being quite technical, but developers will need to fully understand implications of these changes when considering purchasing new sites.
The National Building Code is updated annually, and in 2016 the NCC 2016 is due to be adopted Australia-wide on 1st May 2016.
A small change in the definitions section will now alter how a building’s 25.0m Effective Height is measured.
Previously the Effective Height was determined from ‘….the floor of the topmost storey …. from the floor of the lowest storey providing direct egress to a road or open space’
The new 2016 definition of Effective Height removes any reference to ‘the lowest storey providing direct egress to a road or open space’, and clarifies how stories are determined.
WHAT IS THE IMPACT OF THIS?
Any building above the 25.0m Effective Height calculation requires 2 fire escape stairs, stair pressurization, sprinklers, more water tanks and fire detection systems. This reduces the useable floor plate area and adds significantly to construction costs.
By altering the definition of Effective Height and how the 25.0m Effective Height is calculated, buildings on sites that slope away from the road (or that even have excess side to side cross-fall) will be deemed to be taller, as the criteria for measurement will now include basement or semi-basement levels that are stories within the 25.0m measurement.
WHEN IS A BASEMENT STOREY INCLUDED IN THE EFFECTIVE HEIGHT CALCULATION?
The determination of whether a basement is included in the rise in storey calculation or not is determined by the relative level of the surrounding finished ground level. In Queensland, if the surface of the floor level is 1.0m or more above finished ground, it will now be included in the calculations for ‘Effective Height’.
In general, this will apply to sites where the ground slopes away from the street or have significant side to side cross-fall, but not where the ground slopes up from the street.
HOW DOES THIS EFFECT MY CURRENT PROJECT?
We understand that the particular NCC version that a project will be assessed under relates to when ‘completion of substantial design’ has been completed. As this is somewhat objective, generally the date that a Building Certifier is appointed will determine which version of the NCC it will be assessed under. Accordingly, this should not affect projects that currently have a Building Certifier appointed, but is likely to impact on projects where substantial design work has not been completed and the Certifier is appointed after 1st May 2016.
Please check with your Building Certifier if you have any further detailed questions.
Article by Scott Whiteoak & Dan Volpato, with assistance from McKenzie Group Consulting.