Should I use brown or green pressure-treated for my Vancouver deck?

Brown pressure-treated lumber is the better choice for deck construction in Metro Vancouver. The brown colour comes from MicroPro Sienna treatment, which uses a more advanced preservative system that performs better in our persistently damp climate compared to the older green ACQ treatment.

MicroPro Sienna (brown PT lumber) offers several advantages for Vancouver's marine climate. The copper-based preservative is more evenly distributed throughout the wood fibres, providing better protection against moisture-driven rot and fungal decay. The treatment also includes a water repellent that helps the lumber resist checking, warping, and splitting as it dries — important in our high-humidity environment where lumber movement is ongoing rather than just seasonal. Brown PT lumber typically has lower moisture content when purchased, meaning less shrinkage and movement after installation.

Green pressure-treated lumber uses the older ACQ (Alkaline Copper Quaternary) treatment, which is still effective but more corrosive to standard fasteners and hardware. Green PT lumber also tends to have higher initial moisture content, leading to more pronounced shrinkage, checking, and warping in the first year after installation. While green PT lumber costs slightly less upfront, the improved stability and performance of brown PT lumber makes it worth the 10-15% price premium for deck applications.

Both treatments require ACQ-compatible fasteners — stainless steel or hot-dipped galvanized screws and connectors. Never use standard zinc-plated fasteners with either treatment, as they'll corrode rapidly in Vancouver's damp climate and fail prematurely. For coastal properties in West Vancouver, North Vancouver's waterfront, or White Rock, stick with stainless steel exclusively due to salt air exposure.

For deck surfaces, consider your long-term plans. If you're planning to stain or paint the deck, brown PT lumber takes stain more evenly and looks more natural. If you're building the deck structure only (posts, beams, joists) and installing cedar or composite decking on top, either treatment works structurally, but brown PT lumber's superior stability makes installation easier and reduces callbacks for loose boards or protruding fasteners.

Maintenance requirements are similar for both treatments — annual cleaning and staining every 2-3 years in Metro Vancouver's climate to prevent surface mould growth and UV degradation. However, brown PT lumber's built-in water repellent gives you a longer grace period before staining becomes critical.

Need help finding a deck builder experienced with proper PT lumber selection and installation? Vancouver Deck Contractors can match you with local professionals who understand Metro Vancouver's unique climate requirements.