Weather resistant structure and method of making

A rail comprising:

• an elongated wooden core;
• a weather and abrasion resistant protective plastic coating extruded upon and surrounding said core in contact relation therewith, said coating having a thickness of more than about 0.030 inch;
• and
• a plurality of valve means in said coating for opening responsive to pressure from the core side of said coating, permitting vapor to pass from said core through said coating and blocking the flow of water through said coating toward said core, said perforation means being formed in said coating without removing any said coating material, and including slits extending completely through said coating and spaced apart along the longitudinal axis of said rail.

The method of manufacture of a rail having a protective coating sheath therearound comprising the steps of:

• selecting an elongated piece of wood;
• and
• introducing said wood along its longitudinal axis into a crosshead die, said crosshead die being mounted on a plastic extrusion machine;
• subjecting said wood to a vacuum;
• extruding a thermoplastic resin on said wood while maintaining said vacuum and forming a protective coating enclosing said core, said coating having a thickness of at least about 0.020 inch thereon;
• and
• allowing said coating to cool, said method including the step of forming a plurality of spaced perforations through said coating without removing any of the coating material, said perforations defining valve means for releasing vapor from said wood through said coating and substantially preventing the passage of water through said coating toward said wood, said valve means being openable responsive to pressure from the core side of said coating.