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Frequently Asked Questions
What pressure-treated lumber does Windsor Plywood carry?
Windsor Plywood carries pressure-treated SPF and Douglas fir lumber in standard dimensional sizes including 2x4, 2x6, 4x4, 4x6, and decking profiles, along with pressure-treated plywood. Treatment ratings cover above-ground (UC3B), ground contact (UC4A and UC4B), and freshwater contact applications. Both standard green-tone and MicroPro Sienna brown-tone treated lumber are available.
What do the UC treatment retention levels mean?
UC ratings classify pressure-treated lumber by intended use and exposure. UC2 is for interior damp locations. UC3A is for above-ground exterior exposure with paint or water repellent. UC3B is for above-ground exterior exposure without a protective coating. UC4A and UC4B are for ground contact. UC4C and UC5 cover extreme exposure including saltwater splash zones and permanent wood foundations. Match the UC rating to the exposure condition of your application.
Is modern pressure-treated lumber safe for vegetable garden beds and play structures?
Yes. Since 2004, residential pressure-treated lumber in Canada has used copper-based preservatives (ACQ, CA, or MCA) that replaced the older arsenic-containing CCA treatment. These formulations are considered safe for vegetable garden beds and children's play structures when the lumber is fully dry before use. Allow new treated lumber to dry for several weeks before placing in direct contact with vegetable growing areas.
What fasteners must I use with pressure-treated lumber?
Use hot-dipped galvanized, stainless steel, or fasteners specifically labelled for use with treated lumber. The copper in modern preservatives reacts with standard zinc electroplated and bright fasteners, causing rapid corrosion that weakens connections and causes staining. All metal hardware including joist hangers, post bases, and structural connectors must also be rated for copper-treated lumber compatibility.
Can pressure-treated lumber be painted or stained?
Yes, once the lumber has dried fully. New pressure-treated lumber often contains significant residual moisture from the treatment process that prevents proper paint and stain adhesion. Test dryness by sprinkling water on the surface — if water beads, wait longer. Once dry, apply a quality exterior primer followed by paint, or a penetrating exterior stain. MicroPro Sienna's warm brown tone blends better with exterior stains than standard green-tinted treated lumber.