Exposed fastener metal roofs, a seemingly economical choice, present a unique set of challenges that merit careful consideration. The Metal Construction Association (MCA) emphasizes the importance of proper installation techniques, because improper methods can exacerbate existing issues related to the exposed fastener metal roof. One critical aspect is the thermal expansion and contraction of the metal panels; this attribute directly affects fastener integrity over time. Furthermore, neglecting the recommended fastener spacing, as often outlined by the manufacturer’s specifications, can lead to premature failure. Water infiltration, a common problem, frequently occurs around the fasteners of an exposed fastener metal roof and can compromise the building’s structural integrity.
Image taken from the YouTube channel AEP Span Architectural Metal Roofing & Siding , from the video titled How to locate Exposed Fastener Metal Roofing and Siding from AEP Span. .
Understanding the Pitfalls of Exposed Fastener Metal Roofs
An exposed fastener metal roof is a roofing system where the screws or fasteners used to attach the metal panels are visible on the roof’s surface. While often chosen for their affordability and ease of installation, it’s crucial to understand the potential problems associated with this type of roofing before making a decision. This guide provides a comprehensive overview of those problems.
What Exactly is an Exposed Fastener Metal Roof?
This roofing style relies on fasteners that penetrate the metal panels directly to secure them to the underlying structure. Unlike concealed fastener systems, there’s no overlapping metal to hide or protect the screws.
Common Materials Used
- Steel: Galvanized steel is a common and relatively inexpensive option.
- Aluminum: Offers better corrosion resistance than steel, making it suitable for coastal environments.
- Galvalume: Steel coated with aluminum and zinc, offering a balance of strength and corrosion resistance.
Key Problems Associated with Exposed Fastener Metal Roofs
The direct exposure of fasteners is the root cause of many issues.
1. Leakage Problems
This is perhaps the most significant concern.
- Expansion and Contraction: Metal expands and contracts with temperature changes. This movement puts stress on the fasteners and the surrounding metal, potentially loosening the seal over time.
- Fastener Degradation: The exposed fasteners are directly exposed to the elements, including rain, snow, UV rays, and pollutants. This can lead to corrosion, rust, and eventual failure of the fasteners.
- Material Compatibility: If the fasteners are not compatible with the metal roofing panels, galvanic corrosion can occur, accelerating the degradation of one or both materials.
- Improper Installation: Incorrectly installed fasteners, such as overtightening or undertightening, can compromise the roof’s watertightness from the start.
2. Shorter Lifespan
Exposed fastener systems generally have a shorter lifespan compared to concealed fastener systems.
- Reduced Panel Life: Due to the stress and potential for leaks around the fasteners, the roofing panels themselves might degrade faster.
- Frequent Maintenance: Expect to inspect and potentially replace fasteners more frequently to prevent leaks and maintain the roof’s integrity.
3. Aesthetic Concerns
While aesthetics are subjective, exposed fasteners can detract from the overall appearance of a building for some people.
- Visible Fasteners: The grid of visible fasteners is a defining visual characteristic, but it might not be preferred by all homeowners or business owners.
- Potential for Rust Staining: Corroding fasteners can cause unsightly rust stains to run down the roof panels.
4. Limited Wind Resistance
Compared to concealed fastener systems, exposed fastener roofs often have lower wind resistance ratings.
- Fastener Pull-Out: In high winds, the force exerted on the panels can cause the fasteners to pull out, leading to panel damage and potential roof failure.
Mitigating the Risks
While problems exist, several measures can be taken to minimize the risks associated with exposed fastener metal roofs.
1. Proper Fastener Selection
- Material: Choose fasteners made of materials that are compatible with the roofing panels and offer excellent corrosion resistance. Stainless steel or specially coated fasteners are often recommended.
- Type: Use fasteners specifically designed for metal roofing applications. These fasteners often have specialized washers or seals to create a watertight connection.
2. Professional Installation
- Experienced Contractors: Hire a roofing contractor with extensive experience installing exposed fastener metal roofs. Proper installation is crucial for ensuring the roof’s long-term performance.
- Following Manufacturer’s Instructions: Adhere strictly to the manufacturer’s installation guidelines, including torque specifications for the fasteners.
3. Regular Maintenance
- Routine Inspections: Conduct regular roof inspections to identify any signs of fastener corrosion, loosening, or damage.
- Prompt Repairs: Address any issues immediately to prevent them from escalating into larger problems.
4. Considering Underlayment
- High-Quality Underlayment: Install a high-quality underlayment beneath the metal panels to provide an extra layer of protection against water intrusion. This is especially important in areas with heavy rainfall or snow.
Comparison Table
| Feature | Exposed Fastener Metal Roof | Concealed Fastener Metal Roof |
|---|---|---|
| Cost | Lower | Higher |
| Installation | Easier | More Complex |
| Leakage Risk | Higher | Lower |
| Lifespan | Shorter | Longer |
| Aesthetics | Can be less appealing | Typically more appealing |
| Wind Resistance | Lower | Higher |
| Maintenance Needs | Higher | Lower |
So, before you commit to an exposed fastener metal roof, make sure you’ve weighed the pros and cons. Understanding the potential problems with an exposed fastener metal roof is key to making the best decision for your property. Good luck!