Helpful Siding Terms

Locking System


The locking system joins two panels together. It enables the siding to stay firmly in place and resist lifting up in strong winds. It also creates a rigid beam along the panel to help span wall imperfections. A properly designed locking system should always allow the panel to slide freely within the lock.

Nailing Hem

Nailing hem

The nailing hem is the top edge of a panel that’s nailed to the wall. It should have elongated slots that allow the panel to slide on the nail and to expand or contract with weather extremes. For areas that experience high winds, insist on reinforced double hems designed to withstand hurricane-force winds.

Panel Thickness and Rigidity


Thicker, higher gauge panels are better. Thick, rigid panels with double nail hems provide greater wind resistance, withstand dents and lie flatter and straighter against the wall. Thinner gauge works well for stable climates; thicker gauge is recommended for areas with high winds and extreme temperature changes.

Finish and Profile

Polar Wall Plus! Profiles

Finish refers to the texture of the panel. Typical finishes are brushstroke, wood and cedar grain. Profile refers to the specific design and exposure size of a panel. Typical profiles are clapboard, Dutch lap, beaded and vertical. Each profile and finish creates a unique exterior look and is a matter of personal choice.

Panel Projection

 Profile - Dutchlap

Panel projection is a measure of the distance a siding panel extends out from the wall. Projection affects panel performance, rigidity, and shadow line or aesthetics.

Windload Pressure


Windload pressure is the measurement of how well a panel can be expected to perform in high wind areas. The windload pressure rating identifies actual windload capacity.

Color Quality

Color Hold

Panels formulated with high quality ingredients retain color much longer and make matching panels during repairs or remodeling easier. Look for siding products that feature an innovative capstock giving the panel exterior superior fade resistance, as well as color that goes all the way through the panel. Avoid siding with a gray backing.