The density curve

Schedule 2 of the determination is a grid: about 105 suburbs down the side, eight dwelling-count bands across the top. The rate you pay is selected by the total number of dwellings after the variation, not by how many you are adding — and it falls as the total rises.

That produces a curve most people get wrong, because the per-dwelling rate applies to every additional dwelling, not just the marginal one.

So in O'Connor, two dwellings is close to the worst configuration available: you pay the highest rate in the schedule and get the least product to spread it over. In Chapman, two dwellings works. Same rules, opposite answers, and the only way to know is to have the schedule. What a second dwelling costs and what stops it is the same question asked one block at a time.

What the curve does not tell you

It prices the charge. It does not tell you what you can actually build. Zone, block size, plot ratio, the density targets in the Residential Zones Technical Specifications, private open space, solar access, parking and the shape of the block all constrain the achievable yield — and a three-dwelling scheme on a 600 m² block may be arithmetically attractive and physically impossible.

Where the block is the binding constraint, the site can be made bigger. Building a site out of several blocks moves a scheme along this curve rather than up it: the dwelling count that was physically impossible on one block becomes ordinary across two, and the rate that applies falls, because the rate is selected by the total.

The curve also stops being purely a pricing question at three. From 1 October 2026 a three-dwelling scheme requires a property developer licence, and the trigger is lodging the development application — a cost and a lead time that Schedule 2 does not show.

Use the curve to decide which configurations are worth designing. Then get someone to design them.