Why Aluminum is the Dominant Choice for Metal Roof Mounting
Aluminum has become the industry standard for residential and
comercial metal roof solar mounts for several critical reasons:
1.
Exceptional Corrosion Resistance: This is the primary advantage. Aluminum naturally forms a protective oxide layer when exposed to air, making it highly resistant to rust and corrosion. This is crucial for a system intended to last 25-40 years on a roof exposed to rain, snow, and salty coastal air. 2.
High Strength-to-Weight Ratio: Aluminum structures are very strong yet lightweight. This minimizes the additional dead load on the roof structure, a key engineering consideration. It also makes the components easier for installers to handle, improving safety and efficiency. 3.
Non-Galvanic Corrosion Compatibility: When two dissimilar metals touch in the presence of an electrolyte (like water), they can create a galvanic reaction that corrodes the more active metal. Aluminum and the most common metal roofing material—Galvalume (steel coated with an aluminum-zinc alloy)—are relatively close on the galvanic series. When proper installation practices are followed (using compatible clamps and often with a separator pad), the risk of significant galvanic corrosion is very low. This is a major advantage over steel mounts on a metal roof. 4.
Durability and Longevity: High-quality aluminum alloys (like 6005-T5 and 6061-T6) used in solar mounting are designed to withstand decades of UV exposure, temperature swings, and high wind loads without significant degradation. 5.
Recyclability: At the end of its life, the aluminum mounting system is 100% recyclable, contributing to the overall sustainability of the solar installation.
Primary Types of Aluminum Mounting Structures for Metal Roofs
1. For Standing Seam Metal Roofs (The Premium Solution)
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Mounting Method: Seam Clamps. •
How it Works: Specialized aluminum clamps are securely fastened directly onto the vertical seams of the roof. The aluminum mounting rails are then attached to these clamps. •
Key Advantage: No Penetrations. This is a "penetration-free" system. The weathertight integrity of the roof membrane is completely preserved, eliminating the primary source of potential leaks. This is the gold standard for a reason. •
Components: •
Seam Clamps: Made of forged or cast aluminum, these are engineered to grip the seam securely without compromising it. •
Mounting Rails: Aluminum rails run perpendicular to the seams. Panels are attached to these rails. •
L-Feet/Attachments: In some systems, the clamp has an integrated post or an L-foot that the rail attaches to.
2. For Through-Fastened (Corrugated) Metal Roofs
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Mounting Method: Penetrating Mounts. •
How it Works: Aluminum L-feet or stanchions are bolted directly to the roof structure throughthe metal panels. This requires locating the underlying purlins (structural supports). The mounting rails are then attached to these feet. •
Critical Consideration: Waterproofing. Because this method creates new holes in the roof, extreme care must be taken to seal them. This is done with: •
Butyl Tape: A thick sealant tape is placed under the base of the foot. •
Flashing: A metal or composite flashing is integrated under the roof panel and over the foot's base, directing water away from the penetration. •
High-Grade Sealant: A high-quality sealant (like silicone or urethane) is applied around the lag bolts.
Key Design and Engineering Considerations for Aluminum Structures
1.
Wind Uplift Calculations: This is the most critical engineering factor. The mounting system must be certified to withstand the specific wind speeds of the location. Engineers calculate the loads and determine the required spacing between clamps or feet to prevent the array from being lifted off the roof. Systems are tested to standards like ASTM E1516. 2.
Thermal Expansion: Both the metal roof and the aluminum racking expand and contract with temperature changes. The design must accommodate this movement. On standing seam systems, the clamps often allow for slight lateral movement along the seam. Rail splices are also designed to be flexible. 3.
Electrical Grounding: The entire aluminum structure must be properly bonded and grounded to the building's grounding electrode system. This is a safety requirement to protect against electrical faults and lightning strikes. Specialized grounding lugs that bite through the rail's anodized layer are typically used. 4.
Snow Loads: In snowy regions, the system must be designed to hold the weight of accumulated snow without deflecting excessively. This can influence the spacing of rails and supports.
Leading Brands and Product Examples (Aluminum-Specific)
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S-5!: The industry pioneer. They manufacture the iconic ColorGard and SolarGard clamps that attach to the seam. Their strength is in the attachment; installers then use rails from partners like IronRidge or Unirac. •
IronRidge: Known for their complete, engineered systems, including their X-R100 rail and Standing Seam Foot. They offer a full suite of aluminum components designed to work together seamlessly. •
K2 Systems: Popular for their user-friendly, tool-less components. Their Base S and L-Foot S systems for standing seam roofs are designed for very fast installation. •
Ecolibri Solar Solutions: Specializes in low-profile, aluminum solutions specifically for metal roofs, including products for tricky trapezoidal profiles.
The Future: Trends in Aluminum Metal Roof Mounting
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Rail-Less Systems: To reduce material and labor costs further, some companies offer systems where solar panels attach directly to aluminum brackets mounted on the seams. This creates an ultra-low-profile appearance. •
Integrated "Plug-and-Play" Solutions: Manufacturers are creating complete kits tailored to specific metal roof profiles, simplifying the design and procurement process for installers. •
Focus on Speed: The biggest cost is labor. Innovation is heavily focused on designs that allow for faster, simpler installation with fewer tools and steps, such as snap-together components and pre-assembled modules.