A lapboard siding and trim system is provided in which trim siding components for board-and-batten siding and associated trim components are manufactured using a co-extrusion process, whereby wood/thermoplastic resin composite material and polyvinyl chloride thermoplastic resins are co-extruded through a single die assembly, thereby producing a trim piece having a plastic composite component, that will be visible following installation, fused under heat and pressure to the polyvinyl chloride standoff and attachment fins, that will be hidden following installation. Also provided is a lapboard siding and trim system in which siding components for clapboard siding are manufactured by extruding wood/thermoplastic resin composite material through a die. Associated trim components are manufactured using the co-extrusion process described above. The siding and trim components are completely waterproof, and installation proceeds with almost no face nailing and almost no caulk.