HardieSmart® Blade Wall System
Fire Separation in the Tightest Spaces on Site
Cantilevered balconies, projecting wall elements and the narrow gaps between attached dwellings at ground level all share the same design constraint: there’s very little room for a fire-rated wall assembly, but the fire separation requirement doesn’t go away just because the space is tight. Conventional twin-frame or masonry separating walls simply don’t fit in these locations without eating into usable space that the design can’t spare.
The HardieSmart® Blade Wall System is built for exactly this problem. A single-layer wall system, no cavity, no twin frame, starting from just 102 mm thick, delivering a Fire Resistance Level of up to one hour in a genuinely compact profile. Its single-layer design means no fire lining is required between tenancy frames, which removes a specific weather-exposure risk: fire linings sandwiched between frames in exposed locations like cantilevered balconies are vulnerable to moisture ingress and mould growth if the outer layer is ever compromised. The Blade Wall System sidesteps that risk entirely by not requiring the sandwich in the first place.
102mm
Minimum wall thickness
1 hour
Fire Resistance Level achievable
Single
Layer design: no fire lining sandwiched between frames
Technical Specifications
Fire Resistance Level
Up to 1 hour (FRL) — for timber-framed external separating walls
Suitable building class
Class 1 and Class 10a timber-framed buildings
Minimum wall thickness
102mm
Construction
Single-layer design — no fire lining required between tenancy frames
Compatible cladding
Most James Hardie™ external claddings may be used
Performance attributes
Fire-resistant · Acoustic · Thermal · Structural bracing
Compatibility
Compatible with other frequently used common wall systems
Primary applications
Cantilevered balcony separating walls · ground wall extensions · projecting fire-rated elements
Comparative benchmark
Compared to standard plasterboard systems with a 90mm timber frame and similar acoustic/fire performance
Where the Blade Wall System Belongs
Blade Wall is purpose-designed for external projections and separating conditions where wall thickness is the binding constraint, situations that the other HardieSmart® systems, designed primarily for full-height ground-to-roof separating walls, aren’t optimised to solve.
Cantilevered balconies
Where two adjoining dwellings each have a cantilevered balcony and the separating wall between them needs to achieve fire resistance in a genuinely thin, lightweight, single-layer profile, exactly the condition Blade Wall was engineered for. Its single-layer design and exposure-tolerant construction suit this specific application better than a twin-frame system designed for full-height separating walls.
Ground wall extensions and projecting elements
Fin walls, privacy screens between adjoining ground-floor outdoor spaces and other projecting architectural elements that need fire separation without the bulk of a conventional wall. Blade Wall’s compact profile keeps these elements visually light while still satisfying the fire compliance requirement.
Tight urban and narrow sites
On sites where every centimetre of separation between dwellings has been fought for at the design stage, Blade Wall’s starting thickness of 102mm recovers space that a bulkier system would consume, directly relevant on narrow-lot infill and high-density attached housing.
Locations with weather exposure risk
Because Blade Wall doesn’t require a fire lining sandwiched between two frames, it avoids the specific failure mode where moisture gets trapped between layers in an exposed location, like a cantilevered balcony soffit, and causes mould growth or lining deterioration that isn’t visible until it’s a real problem.
Featured Projects with HardieSmart® Blade Wall System
Frequently Asked Questions
Why doesn't the Blade Wall System need a fire lining between frames?
The Blade Wall System uses a single-layer design rather than the twin-frame-with-cavity approach used in systems like Intertenancy. Because there’s no cavity sandwiched between two separate frames, there’s no fire lining trapped in a space where moisture could accumulate undetected. This is a specific advantage in exposed applications like cantilevered balconies, where a sandwiched fire lining would be vulnerable to weather-driven moisture ingress and potential mould growth if the outer cladding layer were ever compromised.
What is the minimum thickness of the Blade Wall System?
The HardieSmart® Blade Wall System starts as low as 102 mm thick, the same minimum thickness as the Boundary Wall System, though the two systems are engineered for different applications. Blade Wall is designed for external projections, including cantilevered balconies and tight urban sites; Boundary Wall is designed for full-height external walls at or near the property boundary.
Can any James Hardie™ external cladding be used with the Blade Wall System?
Most James Hardie™ external claddings can be used with the Blade Wall System, giving architects and builders design flexibility in matching the Blade Wall element to the broader facade material palette. Confirm the specific cladding compatibility and any minimum thickness requirements against the current HardieSmart® Blade Wall System Design Guide.
Is the Blade Wall System suitable for full-height separating walls between dwellings?
Blade Wall is specifically engineered for external projections and separating conditions like cantilevered balconies and ground wall extensions, not as a general-purpose alternative to the Intertenancy Wall System for full-height separating walls between attached dwellings. For a full-height common wall between two sole occupancy units, the Intertenancy Wall System is the appropriate HardieSmart® product. Contact our team to confirm the right system for your specific wall condition.