For decades, multi-storey lightweight construction across New Zealand and Australia has relied on a familiar design formula: fibrous insulation tucked between wall framing studs, shielded on the outside by a flexible wall underlay. While this standard setup works for typical low-rise buildings, modern architectural expectations are changing. Mid-rise developments, high-rise residential apartments, and commercial towers face extreme environmental challenges that push standard loose-laid building wraps past their design limitations.

High wind pressures, dynamic structural movements, and complex moisture traps mean that standard methods risk long-term failure. Under heavy, fluctuating wind pressures, traditional loose underlays can easily balloon, flex, and experience fatigue around fixing points. Over time, this degradation allows air leaks and moisture to drive in, leading to structural rot and expensive repairs.

To solve these exact problems, building envelope pioneer Pro Clima has developed the FORTX™ and FORTX™ MELIOR systems. These fully tested, next-generation façade systems give the industry a new and innovative way to design high-performance walls without limits using their continuous, fully adhered WRB: Instead of mechanically fastening or stapling loose wraps over studs, the FORTX™ system uses high-performance self-adhesive weather resistive barriers (WRBs) that fully adhere directly to rigid board substrates. This completely removes the localized wind-stress points that cause traditional underlays to tear, flap, or experience fatigue under high wind pressures.

Unlike traditional construction methods that treat building underlays, insulation, and rigid sheets as separate pieces, the FORTX™ systems bring game-changing innovation to the market:

• A Stand-Alone Weatherization Layer: The biggest innovation is that FORTX™ is independently tested and proven to manage extreme wind pressure and driving rain loads without any cladding attached. Tested to AS/NZS 4284 standards, it achieved a Serviceability Limit State (SLS) of ±3.5 kPa, an Ultimate Limit State (ULS) of ±5.5 kPa, with near-zero air leakage (<0.1 L/s/m²) - completely exposed. The system can remain exposed to harsh weather and direct UV rays for up to 180 days before the cladding is even installed.

• The "Warm Structure" External Insulation (MELIOR): The FORTX™ MELIOR system integrates a continuous external layer of non-combustible ROCKWOOL™ Rainscreen™ stone wool insulation directly over the adhered weather resistive barrier. Moving the insulation to the outside eliminates the thermal bridging caused by metal and timber studs. It wraps the building framing in a warm blanket, shifting the dew point outward and minimising the risk of internal condensation and mould forming.

The system offering splits into two configurations depending on the project's thermal, moisture, and fire safety goals:

1. The FORTX™ System

The baseline FORTX™ system focuses on ultimate airtightness, high wind stability, and exceptional moisture control. It utilises either SOLITEX^® ADHERO FC (a Class 4 vapour-permeable self-adhesive WRB) or SOLITEX EXTASANA ADHERO^® (a Class 3 self-adhesive WRB) applied over the exterior rigid board. When paired with INTELLO^® PLUS - Pro Clima's intelligent air barrier - on the inside of the frame, it creates a highly responsive assembly that stops interior humidity from invading the wall frame, resulting in an incredibly healthy indoor living environment.

The FORTX™ MELIOR system builds on this strong foundation by taking insulation to the outside of the building. Developed in collaboration with ROCKWOOL™, the MELIOR setup introduces a continuous exterior layer of ROCKWOOL™ Rainscreen™ non-combustible stone wool insulation right over the adhesive weather barrier.

Moving the insulation to the exterior creates a "warm structure". By encasing the rigid framing boards in a warm blanket of stone wool, the system eliminates cold spots where interior moisture usually turns into structural mould. The dual insulation setup drastically boosts energy efficiency; for instance, a standard steel stud wall with internal insulation achieves a total R-value of just R1.40 due to thermal bridging (heat escaping through the conductive metal studs). Adding the 50mm external ROCKWOOL™ layer more than doubles that performance to a total R-value of R2.85.

Additionally, because the MELIOR system relies on high-density stone wool, it delivers two massive bonuses for multi-storey buildings:

• Acoustic Comfort: The dense fibrous insulation dampens external city noises, creating quiet, peaceful indoor spaces.

• Fire Safety: ROCKWOOL™ Rainscreen™ is completely non-combustible (satisfying AS 1530.1 criteria), meaning it produces no toxic smoke and will not promote flame spread even if it is directly exposed to fire.

Pro Clima developed the FORTX™ and FORTX™ MELIOR systems to solve pain points for distinct groups across the commercial and residential construction sectors:

1. Cladding System Suppliers (The Big Winners)

Traditionally, cladding manufacturers and suppliers had to spend immense amounts of time and money putting their specific cladding profiles through destructive prototype testing (like AS/NZS 4284) to prove they were weather-tight. FORTX™ changes the game completely. Because the underlying FORTX™ wall assembly serves as a certified, standalone weather protection layer, it passes the code requirements independently. Cladding suppliers no longer need to put their claddings through separate AS/NZS 4284 tests when used over a FORTX™ system. This drastically lowers the barrier to market, reduces compliance costs, and makes their cladding products instantly compatible with low-rise and high-rise weathertightness specifications.

2. Architects and Specifiers

Designers are often restricted by strict building code compliance requirements, forcing them to use standard, pre-approved cladding systems. Because FORTX™ is backed by a third-party endorsed engineering judgment report and an accredited NATA lab test report, architects gain total aesthetic freedom. They can confidently specify unique, custom, or imported cladding materials, knowing the structural wall system beneath manages all the external moisture and wind load compliance.

3. Structural and Façade Engineers

Engineers get absolute peace of mind. Instead of calculating localized wind load stress points or dealing with complex, multi-brand warranty overlaps, they receive a fully systemized, engineered package. The inclusion of components like TFLEX - a vapour-permeable, flexible control joint strip - allows engineers to design for 20mm SLS and 75mm ULS seismic movement and inter-storey transitions seamlessly, knowing the integrity of the building's Weather Resistive Barrier is maintained.

4. Commercial Developers and Main Contractors

For those managing the budget and timeline, FORTX™ reduces on-site risk and fast-tracks the construction schedule. Because the building can be fully wrapped and completely weather-sealed using the adhesive WRB before the cladding arrives, internal fit-outs can start much earlier. It eliminates the risk of water damage to internal framing during construction delays and provides a robust, low-maintenance envelope that drives down future structural warranty claims.