Wood Preservative
Chemical compounds forced into wood under pressure to protect against decay fungi, termites, and marine borers. Common preservatives: ACQ, CA-C, MCA, and CCA (restricted).
In Detail
Modern wood preservatives replaced CCA (chromated copper arsenate) for residential use in 2004. Current systems are copper-based: ACQ (Alkaline Copper Quaternary), CA-C (Copper Azole), and MCA (Micronized Copper Azole). The copper provides fungal resistance while co-biocides handle insect protection. Retention levels (pcf) vary by Use Category: UC3B (0.15), UC4A (0.40), UC4B (0.60). All copper-based preservatives are more corrosive to metal than CCA, requiring HDG or stainless steel fasteners.