Increasing deemed to satisfy height limits for timber construction Cost benefit analysis
This study undertook an analysis of net benefits obtained from increasing the height allowances for the deemed to satisfy (DTS) provisions in the National Construction Code (NCC) for timber construction. The analysis considered DTS provisions for up to 25 metres for building Classes 2 and 3 (multi-residential construction) and Class 5 (office construction).
The most valuable benefit of using timber construction would be shorter construction times compared to traditional steel and concrete construction, with reduced foundation requirements; reduced need for additional services such as fixed cranes; and an increased ability for other trades to work concurrently through the construction process thereby reducing final time to completion.
The analysis estimated that using timber construction would result in cost savings of around $1.1 million for a 4 storey apartment building ($10.8 million traditional build cost reducing to $9.7 million), $1.3 million for a 5 storey apartment and $1.6 for a 6 storey apartment building assuming ten apartments per floor. For a 6 storey commercial building, cost savings of $1.92 million might be expected.
The report estimates that for the overall Australian economy, increased height allowances for timber construction in the NCC would bring approximately $103 million in net benefits over 10 years. This is made up of $98.2 million in direct construction cost savings; $3.8 million in reduced compliance costs; and $1 million in environmental benefits.