Will a granny flat fit in your backyard?
Here is exactly what we check before we say yes.

The first inputs are not ours. The lot boundary and any easements come from the Vicmap cadastre (Land Use Victoria, CC BY 4.0), which is the state record of parcel geometry; the plan of subdivision and certificate of title are ordered to confirm them, because an easement that is on title but missing from the map still binds the land. We treat an empty easement result as "none found in the data", never as a clean title.

The existing house is taken from the best source available in this order: the state-mapped building footprint where one exists, otherwise an open building-footprint dataset, and in every case checked against current aerial imagery, from which the roof outline is detected and the wall line estimated by stepping the eave in about 0.45 m. Where the only source is the open dataset we have measured offsets of 1.4–3.4 m against the imagery, so the footprint is redrawn to the roof and labelled approximate.

The imagery itself has a known error. Satellite tiles are registered to the cadastre only where a state-mapped footprint anchors them; elsewhere the whole image can sit about ±1 m off the title boundary in a random direction. In our own check of 120 sites against agents' overhead photographs on 3 October 2026, the side-passage measurements were right on average (mean difference +0.03 m) but with a standard deviation of 1.12 m. That is why every distance on an assessment map is a screening figure, and why the surveyor's set-out, not the map, decides a build.

The placement engine enforces the same clearances the building and fire rules will later require, so a position that passes the screen is a position a surveyor can usually work with. The granny flat sits behind the front wall of the existing house, at least 1 m from every side and rear boundary measured to the fence, at least 1 m from any easement, and at least 1 m from any shed or structure the aerial detection finds. On a Queensland lot the map planner applies the 1.5 m side and rear setback of QDC MP 1.2 instead of 1 m.

To the main house the default is 1.8 m, the National Construction Code's separation between Class 1 buildings on the same lot. Our standard modules ship with a fire-rated short wall — the 3.24 m end of the 34 m² home, the shorter face of the 60 m² home — so when that face is the one toward the house, 1 m is enough and the engine knows it. Where the long face must turn to the house, 1.8 m is kept.

If the plan does not fit with the existing sheds in place, the engine tries again with the sheds removed, and then with the sheds removed and the trees cleared, and reports which of the three it needed. A "fits after the shed goes" result is drawn in a different colour on the map and said in words on the card; it is not presented as a clean fit.

A granny flat that fits in the yard still has to reach it. The screen measures the widest side passage from the house wall to the fence at 0.5 m intervals and grades it: 3.0 m or more is the corridor the delivery and site machinery need and is marked green; a passage that only allows a person to walk — 0.9 m — is marked red for machinery; between the two is a yellow result that depends on what is in the way and whether a crane position exists from the street or a neighbour. The corridor is also where every service connection will run.

Because the passage is the measurement most exposed to the ±1 m imagery error, the screen is deliberately conservative about it. A measured corridor between 2.6 and 3.0 m is reported as "needs a site check", not as a fail and not as a pass; a corner lot with a second street frontage is reported as having an alternative access; and where an agent's overhead photograph of the lot exists, we measure the passage in that photograph as well and only ever use it to downgrade a result, never to upgrade one.

Zone and overlays are read for the parcel from the Vicmap planning layers, sampling inside the boundary so that a neighbour's overlay touching the fence is not counted as yours. The small second dwelling pathway in Clause 73.03 and the zone tables is summarised on our Victorian rules guide; the screen reports whether the zone is one in which that pathway can apply and lists every overlay on the parcel with its effect, from "no planning trigger" through "may add a condition" to "a permit is required" and "normally excluded". A Floodway Overlay, for example, is treated as excluding; a Vegetation Protection Overlay is a condition on tree removal, not on the dwelling.

What the screen cannot read is the title: a restrictive covenant or a Section 173 agreement can stop a second dwelling on a lot that passes every mapped test, which is why the title-level guide sits beside this one and why the documents are ordered before design money is spent.