Aluminium Deck Subframe.

Engineered TreadTech aluminium deck framing and Unex frameless glass balustrade deliver a high‑performing outdoor space in a coastal, high‑seismic environment

Modern outdoor living spaces demand structural performance, durability, and architectural finesse - particularly when exposed to harsh coastal climates and stringent compliance requirements. On the Kāpiti Coast, a 15 m × 6 m floating deck project delivered on all fronts by combining a purpose‑designed aluminium deck framing system with engineered balustrade integration.

Project Overview

The brief called for a large, low‑maintenance outdoor area that felt visually and spatially connected to the home while maximising uninterrupted ocean views. Waterproofing and architectural detailing prevented any fixings to the building, making a true floating deck the only viable solution.

The project used the TreadTech Aluminium Deck Framing System, a NZ‑engineered aluminium subframe with height‑adjustable pedestals, providing a rigid, level platform capable of supporting decking and occupant loads without compromising the waterproof membrane.

Installed by The Complete Building Company, the deck delivers a minimalist, functional, and fully compliant outdoor space that preserves the building envelope and keeps views clear. A Unex frameless glass balustrade was integrated into the subframe, with site‑specific engineering and design ensuring structural performance and aesthetic continuity.

Engineering Solutions for Complex Constraints

Several technical challenges arose from site conditions and architectural constraints - particularly the region’s high seismic coefficients and membrane‑only substrate requirements:

• No fixings to the building: A bespoke site‑specific Producer Statement (PS1) was developed, with the aluminium framing engineered to act independently of the structure.
• Lateral stability without front upstands: Custom boxed aluminium sections were incorporated to control lateral movement under seismic loading.
• Balustrade overturning resistance: Frameless glass balustrades were integrated via Viking RoofTrak® waterproof fixing brackets, anchoring into the TreadTech frame to resist high moment loads without penetrating the membrane.
• Code compliance: A site‑specific PS1 tailored to the geometry, seismic zone and waterproofing constraints ensured compliance with NZ Building Code requirements.

Integrated Deck Framing + Balustrade Design

By combining precision aluminium framing with bespoke balustrade solutions, the project achieved a seamless performance outcome:

• Continuous recessed fixing channels enabled frameless glass balustrade installation, creating a clean, minimalist aesthetic and uninterrupted coastal views.
• The engineered interface between balustrade loads and the deck frame was developed collaboratively to ensure both visual clarity and structural robustness.
• The aluminium system’s light weight and corrosion‑resistant properties make it well suited to harsh coastal environments.

Performance & Benefits

This floating deck now delivers an elegant but highly durable outdoor space that:

• Withstands intense coastal winds and Wellington‑region seismic forces
• Protects waterproofing membranes by eliminating unnecessary penetrations
• Provides a level, stable platform for long‑lasting outdoor living
• Offers premium aesthetics with a frameless glass finish that enhances ocean views