The American Society for Testing and Materials set the minimum standard for panel thickness at .035 inch. Average thickness is .040 inch. Thicker isn't necessarily better, agrees Ron Burke, technical director for the Vinyl Siding Institute. In this case, the additional lap had greater effect on Th. rigidity than thickness or even butt height. The panel profile, or the width and number of the exposures, contributes to a panel's stiffness by giving it more structural integrity, Shaidle says.
Additional laps make the vinyl siding panel harder to bend.
Locking systems can also help to determine how stiff a panel hangs. A locking system allows two panels to be joined together an facilitates installation. To that end, most locks are similar. Generally called positive locking systems, they enable installers to snap panels into place and walk away with the panels still being still being suspended without being nailed. They must still be nailed according to the manufacturer's instructions.