Attachment Points

How siding panels attach to your home greatly affects their resistance to tear offs in high winds. A “nail hem” locks one siding panel to another and allows the panel to be securely nailed into place. There are three different types of nail hems.

Single Nail Hem

Found on economy panels and offers adequate attachment. Comprised of a single layer of material with nail slots, it is the weakest option against nail withdrawal and wind load strength.

Partially Curled Nail Hem

Found on better panels, this option reinforces the areas most prone to breaking under negative wind load pressure.

Fully Curled Nail Hem

You’ll find this on premium panels – it’s the strongest form of attachment. Because the thickness of the entire upper hem is doubled, pressure during negative wind load is dispersed.

Upper and Lower Locks

Locks work with the nail hems to keep panels in place. Under the nail hem is the “upper lock”. At the bottom of each panel is the lower lock. Upper and lower locks create strong interlocks between panels. If durability is important to you, make sure you select the most strongly secured panels.

Larger Channel Locks

Channel-type locks are best, as they run straighter on the wall and snap into place. This creates a strong interlock, keeping panels tight under high winds. Some manufacturers offer more complexly designed locks which increase locking strength and panel straightness.

Bottom Lock/Return Legs - Reinforced Curls

Similar to a channel lock, these have an increased curl that has been reinforced, which adds more strength to the panels and the attachment points.