In December 2011 the ACT Legislative Assembly made changes to the Building Act and regulation in relation to signs on building sites.
From 1 July 2012 all building sites, where work is being carried out (or supervised) by a licensed builder (including owner-builders), must display a sign with information about the work being done. This means the sign must be displayed from the first day to the last day of construction.
More information: http://www.actpla.act.gov.au/customer_information/industry/industry_groups/builders_information/signs_on_building_sites