Attaching objects to siding
All external products (downspouts, shutters, and lights, for example) are attached to walls after you’ve applied the vinyl siding.
NOTE: All external fixtures must be attached to a solid backing (such as exterior grade plywood) to provide a secure mounting surface. Never attach a fixture directly to vinyl siding.
When installing external products, you must allow for expansion and contraction of siding.
You can allow for this movement in two ways:
The most convenient way to attach light fixtures is with light blocks. Because they contain receiving channels to hold siding panels, light blocks provide a simple way to allow for expansion.
When attaching other fixtures, drill holes in the siding 1/4" larger than the diameter of screws, bolts, or nails being used to fasten objects. This provides adequate clearance so the siding can move freely underneath attached objects. When attaching objects, do not fasten tightly. It is also recommended that you apply caulk around the screws.
Fitting at light blocks
When cutting panels to fit at a light block, be sure to allow for expansion. Allow 1/4" to 3/8" for expansion for horizontal siding. For light block with vertical siding, it should be 1/4” to 3/8” at the side and 1/2” on top of the block.
The ideal application has a joint between the two shutters where the shutters are secured to the home. In this way, the siding panel is not pinned between the two shutters and the siding is allowed free movement.
When there is no joint between the shutters and when the shutters are secured to the home (b), the shutters’ fasteners do not allow the siding panel to move. The siding panel then fails to perform because it cannot expand or contract with the temperature changes.
To prevent this, enlarge the holes in the siding for securing the shutter—the hole should be 1/4" larger than the shank of the fastener. If possible, stagger the screws securing the shutter so that they do not line up on the same panel. It is also a good idea to apply caulk around the screws