How the bays are sized

We let the numbers set the size.

Each bay's size is its share of the loose volume that building a new home produces. Here is the data, the conversion, and every assumption, so anyone can check it. Pilot weighbridge data replaces these estimates as it comes in.

The result.

Central estimate for an Australian brick-veneer, slab-on-ground home. Weight share is our blend of the published sources below. Space share uses measured loose unit weights.

Bay	% of weight	Range in sources	Loose kg/m³	% of space	Built bay	Bay m³

"Built bay" is each bay's share of the station once rounded to whole 622 mm modules (ten per side), so polystyrene and steel get at least one module each. "Bay m³" is the gross space for that many modules; the removable pod inside holds about 20% less. See the fabricator spec.

How we got there.

Six steps, all run in code. The same model drives the Blender station and the numbers on this site.

Collect the splits
Material shares by weight from three published sources, mapped onto the eight BuildBin streams.
Blend for Australia
NZ builds are mostly timber-clad. Australian homes add brick veneer and more concrete, so we carry more rubble than the NZ studies show.
Convert to space
Divide each stream's weight by its loose unit weight from the BRANZ REBRI conversion chart.
Size the bays
Each bay gets its share of the station, so all eight fill at roughly the same rate over a build.
Set the floor
No bay shorter than 0.6 m. The two rows are balanced so each side holds about half the volume.
Replace with real data
Every pilot change-over is weighed by stream. The split, and the bay sizes, update from that.

The sources, side by side.

Percent by weight, mapped to BuildBin bays. None of these is a perfect match for an Australian new home, which is why the central estimate is a blend and the pilot measures the real thing.

BRANZ lists five categories totalling 88%. Its 5% "packaging" is shown under cardboard and covers cardboard, plastic and polystyrene together; its 45% "other" is shown under general. Low et al.'s timber includes fence palings; its general includes builder's waste, fibre cement, fixtures and sweepings.

How much a home produces

A study of New Zealand detached homes measured 32.2 kg of construction waste per m² of floor area for single-storey homes and 24.8 kg/m² for double-storey (Domingo and Batty 2021, as reported by Low et al. 2024). Auckland Council puts an average house build at 4.5 tonnes. BRANZ cites about 4 tonnes. We use 32.2 kg/m² as the central rate, which gives 7.7 tonnes for a 240 m² home. Brick-veneer homes on slabs may run higher, so the site also shows a high case of 45 kg/m² (an assumption, not a measurement).

At 5.34 m³ of loose volume per tonne of mixed new-home waste, 7.7 tonnes is about 41 m³: around seven 6 m³ skips, or about two change-overs of a BuildBin station filled to 85% (about 25 m³ usable across its eight pods).

What we assumed

Rubble at 30% of weight, between the NZ studies (near zero) and Your Home's general building waste table (37%). Assumption
Polystyrene at 13% of plastics, from the measured NZ build. Measured, NZ
Brick and concrete rubble at 1,100 kg/m³, between BRANZ's concrete rubble (1,165.56) and hardfill (995.46). Plastics at 55 kg/m³, a blend of soft plastic (36.96) and PVC (99.88). Metals at 250 kg/m³, between clean light gauge (194.2) and general metal (379.6). Assumption
Excavated soil is excluded. It is handled separately and never goes in the station.

Sources

Low et al. (2024), Frontiers in Sustainability. Measured waste from eight terraced homes, by weight and by volume.
Australian Government, Your Home: Waste minimisation. Typical building waste table (NSW DECC 2007).
BRANZ, Bulletin 671: Reducing construction waste.
BRANZ REBRI, Waste Minimisation Plan template, material conversion chart (unit weights).
OneRoof, The end of the builder's skip, quoting Auckland Council on waste per house build.
EPA Victoria, Waste levy rates, 2025–26 and 2026–27.
Queensland Government, Waste levy rates.