What 'Shelter in Place' Actually Means for Your NSW Development Application

NSW flood planning has undergone one of its most significant overhauls in decades.

If you are buying flood prone land, planning a new dwelling or lodging a development application (DA), understanding the current rules is no longer optional.

At StraightLine Planning, we work with applicants across Greater Sydney and regional NSW to translate complex flood constraints into viable planning outcomes.

The Old Rules No Longer Apply

For nearly two decades, NSW councils assessed flood risk against the 1 in 100 year flood standard using the 2005 Floodplain Development Manual. That manual has now been formaly replaced by the NSW Flood Risk Management Manual which is a change driven mainly by the findings of the 2022 Flood Inquiry.

The new manual, supported by a technical Toolkit, requires councils to assess risk all the way up to the Probable Maximum Flood (PMF), which represents the absolute worst case rainfall and runoff scenario for a catchment.

This matters for anyone pulling a Section 10.7 planning certificate. Councils are now mapping risk zones that extend well beyond the standard flood planning area, right up to the PMF level. What appears as unconstrained land on an older certificate may carry significant constraints under the new framework.

So What Does 'Shelter in Place' Mean?

The concept of shelter in place comes from a NSW Government guideline targeting flash-flood environments where floodwaters rise in under six hours from the start of rainfall.

NSW planning policy traditionally treated self evacuation as the only acceptable flood response.

The new guideline recognises that in certain fast rising flood scenarios, attempting to evacuate can be more dangerous than remaining inside a properly designed structure.

Shelter in place means designing a building so its occupants can safely remain inside during an extreme flood event, rather than attempting to flee.

The bar to qualify is deliberately high. For a DA to rely on a shelter in place strategy all of the following conditions must be met:

• The site must be subject to flash flooding only, not slow onset riverine flooding such as that experienced along the Hawkesbury Nepean system

• The nominated shelter area must sit above the PMF level

• A structural engineer must certify the building can withstand hydraulic forces, debris impact and buoyancy loads at PMF

• The modelled isolation period must be less than 12 hours from rainfall commencement

• Applicants must demonstrate how occupants will manage without power, mains water or emergency services access during that window

Shelter in place cannot be used for greenfield subdivisions or for sensitive land uses including childcare centres, aged care facilities or medical premises.

How This Affects Your DA

Clauses 5.21 and 5.22 of Local Environmental Plans now reference the new manual's definitions directly. If your site sits within a flood planning area or closer to a waterway than you expected, your DA will need to demonstrate a clear and safe evacuation route or, in qualifying flash flood circumstances a heavily engineered building capable of protecting its occupants without any external assistance.

The state has deliberately shifted the burden of proof onto the applicant. Vague references to SES plans or general emergency protocols will not satisfy a council flood assessment under the current framework.

Work With Planners Who Know Flood Constraints

Whether your site sits within a mapped flood planning area or you are uncertain about your Section 10.7 certificate, our team can assess your constraints and advise on the most appropriate pathway forward.