Yes, you can build a granny flat (secondary dwelling) where a pool used to be, but it requires proper pool removal, compaction certification, geotechnical assessment, and the same planning approvals that apply to any granny flat in NSW. The pool’s former presence introduces additional engineering requirements for the foundations, which must account for the disturbed soil profile in the fill zone.
This guide explains the approval pathway, the ground condition requirements, and what to plan for if a granny flat over a former pool site is your end goal.
The Appeal: Why Build a Granny Flat Where a Pool Was?
Many Hunter region property owners are discovering that the space occupied by an old, neglected pool is actually ideal for a granny flat:
- Size: A standard backyard pool (50-80sqm footprint) is large enough to accommodate a one or two-bedroom secondary dwelling
- Position: Pools are typically positioned at the rear of the property, away from the street, exactly where a secondary dwelling should sit for privacy
- Services: Pool areas often already have electrical conduits, water supply, and sometimes drainage connections nearby, reducing secondary dwelling servicing costs
- Value return: A granny flat that can be rented out typically generates $350 to $600/week in the Newcastle and Lake Macquarie rental market, providing far more return than a pool ever could
The combination of pool removal ($15,000 to $30,000) and granny flat construction ($100,000 to $180,000 for a quality turnkey unit) is increasingly a deliberate strategy among Hunter region homeowners. The same made-ground logic applies at a larger scale if you’re planning a subdivision or duplex instead of a granny flat; see our guide to removing a pool for subdivision for that sequence, or can you build a duplex over a filled-in pool? if a partial fill-in has already been done and you’re wondering whether it needs to be re-opened. For a broader look at how pool removal can affect land value across different Hunter suburb types, not just for a granny flat specifically, see our land value after pool removal guide. If you’re demolishing the existing house entirely rather than adding a granny flat, see our guide to pool removal before a knock-down rebuild for how that sequencing differs.
NSW Planning Rules for Secondary Dwellings (Granny Flats)
Secondary dwellings are primarily governed by State Environmental Planning Policy (Housing) 2021 (previously SEPP Affordable Rental Housing 2009) and local Environmental Plans. Key provisions for the Hunter region:
Lot size: Secondary dwellings via complying development (CDC) require a minimum lot size of 450sqm for most standard residential zones in Newcastle, Lake Macquarie, and Maitland. Most suburban blocks in the Hunter region exceed this threshold.
Floor area: The secondary dwelling’s gross floor area cannot exceed 60sqm under the CDC pathway, or up to 100% of the main dwelling’s floor area (capped at 60sqm) under some council DAs. Check with your council’s planning team for the applicable controls.
Setbacks: A secondary dwelling must maintain minimum setbacks from boundaries, typically 3m from rear boundary, 0.9m from side boundaries in many zones. As pools are often close to boundaries, the former pool location may need careful assessment to ensure setback compliance. See our dedicated guide on pool removal for a secondary dwelling: setbacks and site coverage for how these limits interact with the old pool footprint in more detail.
Approval pathways:
- Complying Development Certificate (CDC): Approved by an accredited private certifier without council DA, provided the development meets all CDC criteria under the Housing SEPP. Faster, typically 10-20 days.
- Development Application (DA): Full council assessment. Required if the site or development doesn’t meet CDC criteria, or if the property is in a heritage conservation area. Takes 3-6 months typically.
For how the CDC pathway applies specifically to the pool removal component of a project like this, rather than the granny flat build itself, see our guide on pool removal and complying development (CDC) in NSW.
The Ground Condition Challenge
This is the critical difference between building a granny flat on a former pool site versus unoccupied ground: the fill zone left after pool removal is made ground, disturbed, filled soil that does not have the same engineering properties as natural undisturbed ground.
Made ground presents two key problems for footings:
- Settlement: Even with good compaction, filled soil continues to settle over time, particularly in the first five to ten years. A slab or footings placed on settling fill without appropriate engineering design will crack.
- Unknown profile: The depth of fill, the mix of materials, and the moisture content vary through the fill zone in ways that natural soil doesn’t. This makes standard footing design inappropriate.
The solution is engineering, specifically:
- A geotechnical site investigation to characterise the fill profile and make recommendations for footing design
- A compaction certificate confirming the fill meets density requirements
- A structural engineer’s footing design appropriate for made ground conditions
Without these, no building certifier will approve construction of a habitable building on a former pool site.
Geotechnical Investigation Requirements
For a granny flat on a former pool site, a geotechnical investigation typically includes:
- Borehole or test pit investigation to profile the fill and underlying natural soil
- Standard Penetration Tests (SPT) or Dynamic Cone Penetrometer (DCP) to assess soil stiffness
- Soil classification under AS 2870 (Residential Slabs and Footings)
- Site class determination (typically Class P, “Problem” site for made ground)
- Footing recommendations specific to made ground and fill conditions
The geotechnical report is prepared by an NATA-accredited geotechnical firm. In the Hunter region, several firms operate out of Newcastle and Lake Macquarie providing this service. Budget $1,500 to $4,000 for a thorough investigation.
See our detailed guide on geotechnical reports after pool fill-in and compaction certification for what these documents involve.
Footing Design for a Granny Flat on Made Ground
Standard residential slab-on-ground footings (AS 2870 Class M or H sites) are not appropriate for made ground. Your structural engineer will likely specify one of:
| Footing Type | When Used | Typical Cost Premium |
|---|---|---|
| Deepened strip footings (to natural ground) | Fill is relatively shallow (<1.5m) | 20-40% above standard |
| Bored piers (to natural soil below fill) | Fill is deep (1.5m+) | 50-100% above standard |
| Raft slab with stiffening beams | Moderate fill, good compaction | 30-60% above standard |
| Waffle pod raft on compacted fill | Good compaction, shallow fill | 20-40% above standard |
The geotechnical report will recommend the appropriate system. Design by a structural engineer is then required, and that engineer signs off on the footing design before the CDC or DA is approved.
For a typical pool fill with 1.5-2.5m of fill depth (standard residential pools), bored piers to natural ground are often the most appropriate solution. Piers are drilled through the fill zone and bear on the natural soil beneath, bypassing the made ground entirely.
Timing: Pool Removal First, Then Granny Flat
The pool must be fully removed and the fill zone properly compacted before geotechnical investigation. This is because the investigation needs to assess the actual fill profile, not the theoretical one. The sequence is:
- Pool removal and full extraction (not partial fill-in, see below)
- Backfill placed in compacted layers with geotechnical oversight
- Compaction testing and certification
- Geotechnical site investigation of the filled site
- Footing design by structural engineer
- Granny flat design by architect or draftsperson
- CDC or DA approval
- Construction
This means there’s typically a minimum of 4-8 weeks between pool removal and being ready to submit a building approval. Budget accordingly.
Why Full Removal Is Essential (Not Partial Fill-In)
If you’re planning a granny flat on the former pool site, a partial pool removal fill-in is not appropriate. Partial fill-ins leave the pool shell in the ground, a concrete or fibreglass structure below the surface that has unpredictable long-term behaviour and creates an irregular buried obstacle that interferes with footing design.
For any future building use, full pool removal, including complete extraction of the shell and debris, followed by engineered backfill and compaction is essential. This is the only approach that gives the structural engineer a clear, predictable fill profile to design footings around.
Underground Services Check
Pool sites often have underground plumbing (pool pipes) running between the former pool and the equipment pad. These pipes need to be located and either removed or confirmed as capped and inert before granny flat construction. Pipes left under a slab can cause settlement if they collapse or degrade.
Also check for underground electrical conduits (pool lights, pump supply), which should be cut back and capped, not simply abandoned and left energised.
See our guide on easements, sewer mains, and pool removal in NSW for how to identify underground services on your property.
Council Considerations: Heritage and LEP Constraints
In some Newcastle City Council and Lake Macquarie City Council areas, secondary dwellings face additional constraints beyond standard CDC criteria:
- Heritage conservation areas: Secondary dwellings may require DA rather than CDC, and design must be sympathetic to the heritage character of the area
- Bushfire zones: Additional construction standards apply (BAL ratings)
- Flood-prone land: Some former pool sites near waterways or in flood-mapped areas face restrictions on habitable building
See our Newcastle City Council pool removal rules guide and Lake Macquarie City Council guide for local planning context.
Frequently Asked Questions
Can I build a granny flat over a partial pool fill-in? Not advisably. A partial fill-in leaves the pool shell in the ground, creating an irregular underground structure that makes footing design uncertain and building certification very difficult. Full pool removal and engineered backfill is required before a granny flat can be built on the site.
How long does the whole process take, from pool removal to granny flat approval? Realistically, 6-9 months from pool removal to construction approval, then 3-6 months for construction. The geotechnical investigation, footing design, and planning approval stages take most of this time. Pool removal itself typically takes one to two weeks.
Does the granny flat increase my land tax or property tax? In NSW, a granny flat that is rented out commercially may trigger land tax considerations. Consult an accountant or tax advisor, this is outside the scope of planning approval.
What’s the realistic total cost of pool removal plus granny flat? Roughly $120,000 to $220,000 all in. Pool removal: $15,000 to $30,000. Geotechnical and engineering: $5,000 to $10,000. Granny flat construction: $100,000 to $180,000 (budget vary widely by finishes and builder). This represents a significant investment but with rental yield of $350 to $600/week, payback periods of 5-8 years are achievable.
Do I need to tell the council I removed a pool before building? Not in all cases, but the building certifier assessing your granny flat application will ask about the history of the site. Proactively disclosing pool removal, providing the compaction certificate and geotechnical report, and having the pool deregistered from the NSW Swimming Pools Register is the correct approach.
Planning to remove a pool and build a granny flat? Contact Hunter Pool Removals for a free removal quote, we coordinate with geotechnical consultants and can advise on the full sequencing of the project.