How should the nails be placed when installing roofing shingles?

When installing roofing shingles, the placement of nails in horizontal rows ensures a secure and effective installation. This method helps to create a uniform surface that promotes proper water drainage and minimizes the risk of leaks. Horizontal nailing allows shingles to overlap effectively, which is essential for maintaining the integrity of the roof and protecting it from the elements.

Placing nails in horizontal rows also follows the manufacturer's specifications, which often detail the number and positioning of fasteners to achieve optimal performance. Properly nailed shingles provide better wind resistance and help maintain a tight seal, enhancing the lifespan of the roofing material.

The other options overlook the critical nature of the nail placement: nails placed only at the top or bottom edges would fail to provide the necessary stability; a distance of six inches between nails could lead to inadequate fastening and potential blow-offs in high winds; and simply focusing on horizontal rows misses the structural integrity needed from proper placement across the entire shingle.