This page covers one question from the escarpment guide: whether coal mining under or near a block changes what you can build and how. Everything here comes from Subsidence Advisory NSW, the state agency responsible, and I link each page it comes from.
What is a mine subsidence district?
A Mine Subsidence District is an area of NSW where Subsidence Advisory NSW has found a potential risk to buildings from planned, active or non-active underground coal mining. Inside a district, building and subdividing need Subsidence Advisory's approval, so structures are designed for the risk.
The current list names 30 districts, from Appin to Wyong. None of the names is a suburb or council area in Wollongong, Shellharbour or Kiama, but a district's name is not its boundary. The only reliable answer for a particular block comes from the map.
- Districts are declared to protect homes by regulating development, not to stop it.
- Each property in a district is assigned a surface development guideline, numbered 1 to 8, based on the type of mining and the predicted subsidence impact.
- The guideline sets what the design has to allow for.
How do you check if a block is in a mine subsidence district?
Search the address on the NSW Planning Portal Spatial Viewer. The results show whether the property is in a Mine Subsidence District and, if it is, which guideline applies. A second layer shows whether underground coal mining has occurred under or near the property.
- Open the NSW Planning Portal Spatial Viewer.
- Enter the street address or the Lot/Section/DP.
- Read the search results on the right-hand side, and expand each one for details such as the assigned guideline.
- Turn on the layers under "Layers and Legends", then "Subsidence Advisory", to see the district and the Underground Coal Mining Area.
Read the mining layer carefully
Subsidence Advisory says the Underground Coal Mining Area layer shows only where coal extraction has already occurred, not planned future mining. It includes a buffer around historical workings, because old workings may sit slightly away from where the mine plans show them, and it is updated about every three months.
The escarpment guide explains the coal measures in the escarpment slopes. Mine subsidence is one more thing to check alongside the geotechnical report, not instead of it.
When do you need Subsidence Advisory NSW approval to build?
If a property is in a Mine Subsidence District, you need Subsidence Advisory NSW approval before starting work on a new home, an extension or other structure, or a subdivision. Some minor works, such as small carports, decks and fences, do not need it.
There are two ways to apply:
- Directly, through the Subsidence Advisory Portal.
- As integrated development, through your council, which refers the application to Subsidence Advisory where required.
For properties under Guidelines 2, 3, 3A, 6 and 8, councils and accredited certifiers can approve applications without referring them to Subsidence Advisory. Subsidence Advisory says applications that comply with the guideline are approved within 7 calendar days of receipt, and applications needing a merit assessment are determined within 40 calendar days, unless more information is requested.
For a builder, the guideline matters most at design stage, because it can shape the footings and structure. I want to know it before a design is priced, not after.
What happens if mine subsidence damages your home?
Homes and buildings anywhere in NSW, inside or outside a declared district, are eligible for compensation if they are damaged by mine subsidence, provided the correct development approvals were obtained. The approval is what protects the claim.
That is the practical reason not to skip it. A structure built in a district without Subsidence Advisory's approval risks losing the cover the approval would have given it.
What should you ask before buying a block in a district?
Ask your solicitor or conveyancer to confirm with the seller that existing structures were built with the correct approvals, that no unauthorised work has been done, and whether any mine subsidence claim is pending or has been made.
- Check development records with the council.
- Search Subsidence Advisory's register of previously issued certificates. Those certificates confirmed eligibility only for the structures on the property on the date they were issued, and they were discontinued on 30 September 2019.
- Anything built or extended since then needs its own approval to be eligible.
- Building on the Illawarra escarpment: the geology, landslip, bushfire and the council requirements.
- Sloping blocks: what drives the cost: including site classification, which covers mine subsidence.
Sources
Checked on 29 September 2026.
- Subsidence Advisory NSW, Mine Subsidence Districts: what a district is, the list of districts, the Spatial Viewer and the Underground Coal Mining Area layer, buying in a district, and compensation.
- Subsidence Advisory NSW, Development approval process: when approval is needed, exempt works, how to apply, guidelines and timeframes.
- NSW Planning Portal, Spatial Viewer.
General information from a builder, not engineering or legal advice. Confirm the district, guideline and approval pathway for your property with Subsidence Advisory NSW.