Mt Martha: Engineering the Coastal Envelope Pitch, Profile, and Performance.
Mount Martha: Roof Installation
Roof design at TEMSEA isn't just a cosmetic choice; it is structural physics applied to coastal exposure. This Mt Martha project demonstrates how pitch angle, material selection, and penetration strategy combine to create a high-performance envelope that resists the Peninsula's wind, rain, and salt load.
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Why 38 Degrees? Pitch as Performance Engineering
In this specific pitch range, water doesn't just drain—it accelerates. The velocity is high enough to prevent wind-driven rain from forcing its way under laps or around penetrations during southwesterly storm events.
Furthermore, steeper pitches are effectively self-cleaning. Leaf litter and organic debris that would otherwise accumulate in valleys simply slide off. This prevents moisture retention at junctions and significantly extends the service life of sealants and weather barriers. Beyond water management, this pitch creates usable volume in the upper level, offering generous ceiling heights and attic ventilation pathways that provide passive cooling without the energy bill.
Comparing the Performance Equation:
Builders must navigate different trade-offs for every profile:
- Flat Roofs (1–5°): Suit contemporary forms but demand rigorous membrane detailing and aggressive maintenance schedules on the Peninsula.
- Skillion Roofs: Offer clean lines but can create thermal asymmetry, requiring careful orientation to manage solar gain on the dominant face.
- 22–25° Pitches: Australia's "workhorse" angle. Economic, but in coastal zones, they lack the runoff velocity or debris clearance required for high-exposure sites.
For Mt Martha, 38 degrees struck the balance: aggressive shedding and interior volume without overcomplicating the truss engineering.
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Steel roofing at approximately $7kg/m^{2}$ versus concrete tiles at $50kg/m^{2}$ isn't just a weight difference—it is a structural cascade.
Lighter roofing reduces the dead load on trusses, which reduces rafter sizing, wall plate dimensions, and ultimately, footing volume. In coastal builds where engineering certification is mandatory, reducing structural demand translates directly to lower certification costs and simpler foundation design.
Durability in Marine Environments
While tiles offer thermal mass, they struggle with coastal maintenance—cracking from wind uplift, moss growth in damp microclimates, and mortar degradation. Colorbond’s factory-applied coating and Zincalume® substrate provide galvanic protection; even if scratched, the zinc-aluminium alloy sacrificially corrodes before the steel does. Detailed correctly, the expected service life exceeds 70 years.
Multiple Skylights: Daylighting Without Structural Compromise
Every penetration is a potential weak point, but with Colorbond’s continuous sheet profile, the integration is streamlined. Custom flashings tie directly into the profile, creating overlapping weatherproof junctions.
These skylights do more than illuminate; they improve circadian rhythm regulation and create a visual connection to the sky plane—a critical design element when coastal views might be restricted by planning overlays or bushfire management.
The TEMSEA Approach: Resist, Don’t Just React
This roof isn’t a collection of separate decisions—it’s an integrated system. The steep pitch accelerates runoff, the lightweight steel minimizes structural demand, and the skylights leverage that system to introduce light
.At TEMSEA, we engineer roofs to resist the Peninsula's conditions for decades, rather than requiring constant remediation.
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