California Roofing Contractor Exam (C-39 License) Practice Exam

In slate roofing, the nail holes are positioned about one third of the way down from the top edge. This placement lets the slate stay thick enough near the top to resist cracking when you drive the nail, while still leaving a sufficient portion above the hole to help with wind uplift resistance and to be covered by the slate above, which helps keep water from penetrating around the fastener. If the hole were right at the top edge, the slate is more prone to cracking and the nail can be more exposed to movement and weather. If the hole were near the bottom edge, the fastening would be less secure and the slate could be more easily displaced. Random placement would not provide consistent performance or proper weather sealing.