Address
Malabar NSW 2036
Australia's First Rooftop Garden Passive House
Seaforth Passive House
We built this innovative home to meet Passive House principles without formal certification, prioritising healthy indoor air quality, energy efficiency, and mould prevention. The clients wanted a sustainable, comfortable home that would support their family's well-being while ensuring long-term durability and performance.
As a pioneering project, this build also featured Australia's first rooftop garden on a Passive House — presenting unique and complex technical challenges that had never been solved in Australia before.
Our Process: From Knockdown to Completion
01
High-Performance Passive House Construction
BBS was responsible for the entire structural build — slab-to-cladding construction ensuring airtightness and insulation continuity, weather-resistant barriers, air-sealing to prevent moisture intrusion, and custom cabinetry and interior work designed for durability.
02
Engineering Australia's First Rooftop Garden
The rooftop garden required structural reinforcement as the original engineering was too light. We designed a chimney effect airflow system to regulate temperature beneath the garden — maintaining thermal performance without compromising the Passive House envelope.
03
PVC Waterproof Membrane & Rooftop Preservation
A PVC waterproof membrane was carefully installed and preserved to prevent any water infiltration from the rooftop garden into the building envelope below — protecting the airtight layer from above while supporting the full planted load.
04
Pro Clima Airtight Membranes & WRB
We integrated Pro Clima leading airtightness and moisture management solutions throughout the envelope — airtight WRB membranes protecting the home from condensation and heat loss at every junction.
05
BINQ HRV Windows & Ventilation
High-performance BINQ windows and an HRV mechanical ventilation system were installed for optimal air quality and thermal efficiency — delivering fresh filtered air to every room while recovering outgoing thermal energy.
Project Challenges
Engineering Australia's first rooftop garden on a Passive House required reinforcing the structure, as the original engineering design was too light for the garden loads. We had to ensure structural integrity while maintaining Passive House principles — airtightness and thermal insulation — throughout.
A chimney effect airflow system was implemented to regulate temperature beneath the garden without compromising the Passive House envelope. A PVC waterproof membrane was carefully preserved to prevent leaks while supporting the full weight of the planted rooftop garden.
Working with tradespeople unfamiliar with high-performance construction is always a challenge. From preventing damaged membranes to sequencing elements correctly, our aim was to meet the clients' performance targets while keeping to their budget.
Results: A Year-Round Comfortable Home
0.9 ACH — ultra-low airtightness result achieved at completion
Australia's first rooftop garden successfully integrated on a Passive House
Mould-free, healthy living environment via airtight construction and HRV
Year-round thermal comfort with minimal heating and cooling requirements
Chimney effect airflow system maintaining rooftop ventilation without energy loss
Natural materials and high-performance insulation used throughout
Project Outcome
The completed home achieved 0.9 ACH — an ultra-low energy result confirming the home's airtight performance. The rooftop garden airflow system regulates temperature without affecting insulation or energy performance, and the home delivers a mould-free, healthy indoor environment for the family year-round.
“We wanted a home that would be healthy for our family and truly energy-efficient. BBS helped us achieve that while also creating an incredible rooftop garden that we love. It's the perfect balance of sustainability and functionality.”
Homeowners
Seaforth Passive House
