Trus Joist Parallam Plus PSL pressure-treated engineered headers and beams are ideal for exterior applications even in harsh conditions. Decay- and insect-resistant, the wood is treated to the core using wolmanized preservative protection, which eliminates the need for field treatment when cut or drilled. Sourced only from SFI-certified North American forests, the engineered wood is recognized under the National Green Building Standard. Available in eight sizes, the beams can be painted or stained on-site. Weyerhaeuser.