Granny Flat Guide for Adelaide

The 10-step framework

1. STEP 1

   Confirm your block qualifies under the new SA rules

   Under the SA Planning, Development and Infrastructure Act, most residential blocks of 300sqm+ can host a secondary dwelling (granny flat). Below 300sqm or in heritage / character zones, you generally cannot. Council overlays trump state rules - check the SA Planning Portal for your block before paying for a design.

2. STEP 2

   Decide attached, detached or above-garage

   Attached granny flats share a wall with the main house (cheapest, often code complying). Detached are the most flexible but need separate services (plumbing, power, NBN) and may need a separate driveway. Above-garage builds are dense but trigger overlooking and overshadowing rules in most SA councils. Each path has very different cost and approval profiles.

3. STEP 3

   Set a realistic budget

   Adelaide granny flat budgets (2026): basic 1-bed at 50sqm = $130k-$175k. Mid-spec 2-bed at 65-80sqm = $185k-$240k. Architect-designed detached unit with full kitchen = $260k-$350k+. Add $15-30k for site work on sloping or reactive soil blocks. Watch for "marketing prices" that exclude site costs, council fees, and connections.

4. STEP 4

   Check council setbacks, building height and site coverage

   Most SA councils require 3m setback from rear boundary, 1m from side boundaries (or 0m with a fire wall), max 4.5m building height, and total site coverage under 60%. Mawson Lakes, Port Adelaide and Charles Sturt all have additional overlays. Council policy is local - don't assume what worked next door will work for you.

5. STEP 5

   Plan services BEFORE design lock-in

   Detached granny flats need separate plumbing, electrical, gas and NBN connections. Sub-meter or separate meter? Shared trade waste connection or new tapping? These decisions add $8-25k and need to be made before footings are designed. Get a services engineer involved at concept stage.

6. STEP 6

   Decide upfront: rental, family or future-proof?

   Designing for elderly parents (zero-threshold, wheelchair-accessible bathroom, lower benches) costs the same as designing for rental but pays off if mobility changes. Designing for rental needs separate metering, lockable entry and council "Section 219" approvals. Designing for future-proofing covers both - and is usually the smart play.

7. STEP 7

   Get a planning consent if you cannot meet the code

   If your design exceeds setbacks, height or coverage limits, you need a planning consent (not just code-compliant building consent). Planning consents take 8-16 weeks and may require neighbour notification + Council Assessment Panel approval. Plan for 6 months from concept to start-on-site.

8. STEP 8

   Match the builder type to the project size

   A 50sqm granny flat is too small for most volume builders to bother with (low margin), but too big for a handyman extension. Mid-tier "boutique" builders with a granny-flat-specialist line are usually the right fit. Custom builders work too but their min-spend often exceeds $250k.

9. STEP 9

   Get the rental zoning right

   In SA, a granny flat can be rented out separately ONLY if it satisfies the council's secondary dwelling rules. Renting out an "ancillary accommodation unit" (the older, looser category) is technically illegal in some councils. If rental income matters to your numbers, get a planning consultant to confirm your design before contract.

10. STEP 10

    Pressure-test the contract for rear-yard impact

    Standard contracts don't spell out: who repairs the main house garden after construction access, who pays if existing irrigation is cut, who manages temporary fencing. On a granny flat build, you live IN the construction zone for 4-6 months. Write these expectations into the contract before signing.

FAQs