How To Check a Block Before You Buy or Bid

The direction a block faces is fixed, and it decides where the sun lands, which decides which floor plans can give you north facing living areas. It is also the fastest check on the list, about two minutes on a map. For the walk through, see the guide on which way your block faces, or use the free block direction tool.

A north facing backyard is the easiest block to build on, because the living areas can face the yard and the sun at the same time. A south facing backyard is the hard one, because the sunny north side is the street side, where the driveway and garage sit. That is not a reason to walk away, but it is a reason to confirm a plan exists for it before you buy, not after.

In my reviews, width is the dimension that rules out the most plans. Most project homes need a set clear width once the side setbacks come off, and a block that is half a metre too narrow rules out whole catalogues. Measure the frontage on the plan of the land, then compare it against the homes you have in mind. If the block is tight, there are plans drawn for it: see homes under 10 metres wide and under 8 metres.

For a New South Wales address, the free lot check draws the block from the state's cadastre, takes off the setbacks, and shows the buildable envelope, which is the area you can actually put a house in. It then tests real builder plans against that envelope and your driveway side, so you see homes that fit, sitting on the block, with north up.

The same lookup lists the planning attributes that decide how hard the block is to build on: the zone, the height limit, and whether the land is mapped for bushfire or flooding, or carries heritage. None of these is a deal breaker on its own, but each one adds cost or design constraints, and you want to know about them while you can still walk away. Treat the lookup as a first pass: your certifier, council and conveyancer confirm the detail before you commit.

Walk the block. A map cannot show the slope, though the free slope calculator reads an indicative fall off the national elevation model, and a steep fall across the building platform adds retaining walls and site costs that flat land does not have. It cannot show the neighbour's second storey shading the northern boundary, the street trees over the driveway, or the traffic at 5 pm. Easements and covenants sit in the contract of sale, so have your conveyancer read it before auction day, not after.

A block sits in a suburb, and the suburb checks matter as much as the boundary ones. On my own pre purchase inspections I also check the crime rates in the area, the primary school catchments and their results, how close the green space and bushwalks are, and whether nearby bushland is protected open space or a future development site. Look at the mix of owners and renters too: a suburb where rentals sit under about 30 per cent and vacancies under 3 per cent tends to be settled and owner occupied. If a dog is part of the family, check the dog friendly beaches and walks nearby, and check the land valuation, because it drives the council rates and land tax you will pay every year.

The lot check flags flood and bushfire mapping for the block, and it is worth understanding what those flags mean before you rely on them: see the Good Architect guides on flood risk and bushfire risk. For the full worked list, everything I check before buying a property covers the lot, and the buying a block of land checklist is the companion for vacant land.

An auction purchase in New South Wales is unconditional, with no cooling off period, so every check above has to happen before you bid.

Because the lot check runs from just an address, you can screen every block on your shortlist in an evening and go to auction knowing which homes fit the land you are bidding on. If the numbers only work with a plan that does not fit, that is worth knowing before you raise your hand.

If you are buying to develop, the same thinking applies with more zeros. Check whether the block takes a duplex, or screen it against the NSW pattern book terrace and apartment designs on the Pattern Book page, before you settle on a price.