Bush Fire Resistant Granny Flats.

In November 2015, Baldwin O'Bryan Architects won the Bushfire Building Council of Australia's  Innovation Award for the best design concept for this design at Newee Creek in NSW.

 EARTH SHELTERED GRANNY FLATS From $199,710 

Each of the design options below has reinforced concrete walls 200 mm to 275 mm thick, providing excellent bushfire protection and substantial thermal mass for a stable thermal environment. Options A and B both have a heavily insulated metal deck roof with a steel frame, which can be optioned up to BAL FZ. No waterproof membranes are required for Options A and B, which saves considerable cost. All options have a floor plan similar to the one displayed below
OPTION  A has no side retaining walls to further reduce cost.  The base price for Option A is $197,000 for a 60-square-metre 2-bedroom dwelling.
OPTION B is slightly more costly than Option A due to its side retaining walls.
OPTION C has a reinforced concrete vegetated roof and is the more costly option. It could easily be optioned up to meet BAL FZ construction.
The technologies illustrated here can also be applied to much larger houses as well as commercial and industrial buildings
OPTION A
OPTION C
OPTION B
FLOOR PLAN FOR OPTIONS A,B AND C ABOVE
Since the beginning of 2026, we have conducted extensive research and development with our builder and structural engineer to identify ways to reduce costs for earth-sheltered houses and bushfire-resistant buildings generally. Recent advances in permanent formwork systems for reinforced concrete have significantly improved the cost-effectiveness of this construction method. Reinforced concrete is exceptionally bushfire-resistant and offers excellent thermal performance, particularly when coupled with the thermal mass of a soil enclosure. 

REINFORCED CONCRETE NON EARTH SHELTERED GRANNY FLATS 

 The houses illustrated below are designed with permanent formwork, 200 mm-thick reinforced-concrete walls, and concrete roofs, which provide exceptional bushfire resistance and excellent thermal performance. They can be optioned up to BAL FZ by adding bushfire shutters, as illustrated. The floor plan for these illustrations is similar to the 60-square-metre plan shown above, but the principles of this design can be applied to considerably larger dwellings.

 PARTIALLY EARTH SHELTERED OPTION

This partially earth-sheltered option is designed to reduce the costs associated with the large volume of soil required for earth-sheltered buildings, which can be a challenge on some properties. It has reinforced concrete walls, 200 mm to 275 mm thick, with one-metre-wide vegetated sandbag walls for thermal mass, providing a stable thermal environment and excellent bushfire protection. It can be optioned up to BAL FZ with bushfire shutters, as shown in the houses illustrated above. The floor plan for this illustration is similar to the 60-square-metre plan shown above, but the principles of this design can be applied to considerably larger dwellings.
The main challenge in bushfire-resilient design is balancing performance with affordability. Permanent formwork enables reinforced concrete structures to deliver excellent fire performance at low cost and to speed construction. Having the right professional team is critical. Refusals from authorities such as the CFA in Victoria, the RFS in NSW, or local councils are extremely difficult to overturn once issued. Early, informed design decisions are essential to avoiding costly delays or refusals. We have successfully secured planning and building approvals for more than 22 homes in designated Bushfire Prone Areas, including many sites where clients were initially advised that approval was unlikely or even impossible. This success is driven by our deep understanding of state-based planning systems, bushfire regulations and approval pathways, including compliance up to BAL–Flame Zone (BAL-FZ).

How to Check if Your Granny Flat, Shed, or Studio is in Bushfire-Prone Land
You can check whether your granny flat, shed, or studio is on bushfire-prone land by visiting the websites below for your state.
New South Wales (NSW)
Victoria (VIC)
Queensland (QLD)
South Australia (SA)
Western Australia (WA)
Building to the relevant Australian Standard (AS 3959) is mandatory under the National Construction Code in designated bushfire-prone areas.