A plain English explanation of this ACT planning and property term.
northern boundary means a boundary of a block where a line drawn perpendicular to the boundary outwards is oriented between 45o west of north and 45o east of north.
A northern boundary is identified by the direction the boundary faces outward from the block, not simply by whether it appears at the top of a plan. Imagine drawing a line at a right angle to the boundary, pointing away from the property: if that line points within 45 degrees either side of true north, the boundary is a northern boundary. The classification is used in solar-access and building-envelope rules.