In roofing, choosing the right fastening method is essential to ensure the longevity and integrity of the structure. One common approach is to use plastic cap nails under a metal roof. In this technical guide, we’ll explore the key aspects of this method, providing precise information for both technical professionals and those new to roofing.

1. What Are Plastic Cap Nails?

Plastic cap nails are specialized fasteners designed for securing underlayment, roofing felt, and occasionally, insulation, beneath a metal roof. They consist of a nail shaft and a plastic cap, which is typically color-coded to indicate nail length. The cap serves to create a watertight seal and prevent damage to the roof material.

2. Types of Plastic Cap Nails

There are two primary types of plastic cap nails used in metal roofing:

• Round Plastic Cap Nails: These are the most common and are suitable for most metal roofing applications. The round cap ensures even distribution of pressure and minimizes the risk of tearing the underlayment.

• Square Plastic Cap Nails: Square cap nails offer additional stability and are used in situations where greater holding power is required, such as in high-wind areas.

3. Benefits of Using Plastic Cap Nails

• Waterproofing: The plastic cap creates a waterproof barrier, preventing water intrusion and protecting the underlying structure.

• Wind Resistance: Plastic cap nails enhance the wind resistance of the roof, keeping the underlayment securely in place.

• Easy Installation: They are easy to install, making them a practical choice for roofing professionals and DIY enthusiasts.

4. Proper Installation

When using plastic cap nails under a metal roof, it’s crucial to follow these installation guidelines:

• Spacing: Place nails at recommended intervals, typically 6 to 12 inches along the edges and 12 to 24 inches in the field.

• Orientation: Nails should be installed perpendicular to the roof deck to ensure proper holding power.

• Overlapping Cap: Ensure that the plastic caps overlap, creating a continuous seal that prevents moisture ingress.

• Fastening Technique: Nail the underlayment securely to the deck, but avoid overdriving the nails, which could damage the roof material.

• Sealing: For added protection, consider using a roofing sealant or adhesive to seal the caps’ seams.

5. Applications

Plastic cap nails are commonly used for:

• Securing roofing felt or underlayment in preparation for metal roofing installation.

• Fastening insulation materials under a metal roof.

6. Maintenance and Inspection

Regular maintenance ensures the ongoing effectiveness of plastic cap nails:

• Periodically inspect the roof for loose or damaged caps and replace them as necessary.

• If any caps are dislodged or damaged, repair them promptly to maintain the roof’s integrity.

7. Conclusion

Plastic cap nails offer a straightforward yet effective solution for securing underlayment and insulation beneath a metal roof. When installed correctly, they provide water resistance, enhance wind resistance, and are easy to work with. Following proper installation techniques is key to reaping the benefits of this method. Whether you’re a professional roofer or a homeowner tackling a DIY roofing project, understanding the role and proper use of plastic cap nails is essential for a successful and long-lasting metal roof installation.