This case study highlights a technically challenging 5-unit townhouse development in Reservoir, where DE WALKERS managed critical fire-rating compliance requirements associated with attached dwellings, shared party walls, balcony encroachments, and structural elements spanning common accessways.
The development consisted of five attached townhouses with shared walls and interconnected structural interfaces. Due to the close proximity between units, balcony encroachments, and structural beams extending across driveway areas, the project required careful assessment and implementation of compliant fire separation systems in accordance with the National Construction Code (NCC) Volume Two and relevant fire engineering principles.
Given the complexity of the design, a qualified fire engineer was engaged to undertake a detailed assessment and prepare a performance solution strategy for areas where Deemed-to-Satisfy provisions alone were insufficient.
Key Project Challenges
1. Fire Separation Between Attached Townhouses
One of the most critical aspects of the project involved achieving compliant fire separation between adjoining dwellings through shared party walls.
The design required a fire-rated wall system capable of achieving a 60/60/60 Fire Resistance Level (FRL) from both directions. This was particularly important due to the attached townhouse configuration and the close relationship between habitable areas across adjoining units.
To achieve compliance, the project adopted the CSR 24055 fire-rated party wall system, including:
- Two-layer fire-rated lining systems
- Vertical sheeting installation methodology
- Strict fixing and nail spacing requirements
- Fire-rated joint treatments
- Carefully controlled junction detailing between wall and floor systems
All installations were completed in strict accordance with manufacturer specifications and carefully supervised throughout construction to ensure the integrity of the fire-rating system was maintained.
Balcony Encroachment & Performance Solution Assessment
A significant design challenge arose with balconies associated with Units 3, 4, and 5, where portions of the balconies were located within 1.8 metres of another building on the same allotment.
Under NCC requirements, balconies exceeding one metre in height and located within close proximity to adjacent structures required additional fire separation considerations.
As part of the fire engineering assessment, a detailed Performance Solution Report was prepared to provide technical justification for the proposed design approach.
The assessment considered:
- Separation distances between structures
- Fire spread risk between adjoining units
- Balcony construction materials and fire performance
- Occupant evacuation characteristics
- Emergency egress expectations
- Overall building fire load and exposure risk
Following the analysis, enhanced fire-rated construction measures were incorporated into the balcony systems and associated structural elements.
Fire-Rated Structural Elements Over Driveways
Another critical component involved structural beams extending across shared driveway areas.
Due to their location and relationship to adjoining dwellings, these beams required additional fire protection measures beyond standard construction methods.
The project team carefully reviewed all exposed structural interfaces and implemented fire-rated protection systems to maintain continuity of the required FRL throughout the development.
This included:
- Fire-rated beam protection systems
- Continuity of fire-rated construction at junctions
- Coordination between structural and fire engineering requirements
- Careful sequencing and inspection during installation
Inter-Floor Fire Separation Detailing
A particularly sensitive area of the project involved maintaining compliant fire separation at junctions between floor levels and party walls.
The interface between wall systems and floor structures required detailed investigation to ensure the fire resistance integrity was not compromised at transition points.
Special attention was given to:
- Fire-rated floor-to-wall junctions
- Penetration and joint treatments
- Continuity of fire barriers between levels
- Installation tolerances and manufacturer requirements
The project team conducted extensive reviews of CSR system guidelines and ensured all junction details were installed precisely in accordance with approved specifications.
Occupant Risk Assessment Considerations
As part of the fire engineering process, occupant characteristics and evacuation behaviour were also assessed.
The analysis considered that:
- Residents represented a typical residential population familiar with the building layout and egress paths
- Visitors may not be familiar with exit routes but would generally be assisted by residents during an emergency
- Occupants would not normally participate in firefighting activities
- The overall evacuation profile aligned with standard residential occupancy assumptions
These considerations formed part of the broader performance-based fire engineering assessment supporting the project.
Construction Supervision & Quality Control
Due to the complexity and sensitivity of the fire-rated systems, installation quality control was treated as a critical component of the construction process.
Particular attention was given to:
- Material selection compliance
- Layer sequencing of fire-rated boards
- Fixing patterns and spacing
- Joint treatment systems
- Manufacturer installation procedures
- On-site inspections during key construction stages
All critical fire-rated elements were closely monitored to ensure the final installation achieved the required performance outcomes.
Project Outcome
Through detailed fire engineering coordination, performance-based assessment, and strict construction supervision, the project successfully achieved the required fire separation performance across all critical building elements.
The development demonstrated how complex townhouse configurations with balcony encroachments, shared walls, and structural crossover elements can be successfully delivered through a combination of:
- Early fire engineering involvement
- Careful NCC compliance assessment
- Performance solution methodologies
- Strict adherence to tested fire-rated systems
- High-level construction quality control
This project stands as a strong example of DE WALKERS’ capability in managing technically demanding multi-unit developments requiring advanced fire compliance coordination and execution.