Why does hardboard siding peel and/or rot?
Hardboard siding is reconstituted natural wood. It is fabricated by reducing natural wood to fibers, adding resins, and then pressing the fibers together into panels. It can be either tempered or standard. Tempered board is denser and has a higher moisture resistance. Standard hardboard should not be used outdoors in areas where it will be directly exposed to the weather. Peeling is often due to poor maintenance of the coated surface. It generally originates at butt joints and drip edges. Water contact directly with bare hardboard in these areas eventually penetrates into the board, which permeates and expands the compressed wood fibers in the board. This leads to the board rotting. The swelling process is irreversible, resulting in delaminating of both the paint film and the board. SOLUTION: Hardboard must be primed, if it was not primed by the manufacturer. All joints or bare edges must be primed and caulked to avoid contact with water. Vulkem 116 is an ideal caulking to use on hardb
