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Create clean, professional results with premium finishing lumber. Ideal for trim work, cabinetry, furniture building, and detailed interior projects, finishing lumber is kiln-dried, surfaced, and precision-milled for a smooth, consistent appearance. We carry a wide range of profiles, sizes, and high-quality wood species—perfect for painting, staining, or leaving natural to showcase the grain. Whether you're updating a room, crafting custom millwork, or starting from scratch, finishing lumber provides the refined touch your project deserves. As a proudly Canadian company with locally owned stores, Windsor Plywood specializes in hard-to-source wood products and offers personalized, expert advice to help you achieve exceptional results. Visit your local store to explore our full selection of finishing lumber and bring lasting quality and craftsmanship to every project.
Frequently Asked Questions
What is finishing lumber and how does it differ from construction lumber?
Finishing lumber refers to smooth-planed, appearance-grade wood used for trim, moulding, panelling, shelving, and interior millwork. It is graded for visual quality with minimal knots and defects. Construction lumber is graded for structural strength and is not intended for exposed applications where appearance matters.
What species are available in finishing lumber at Windsor Plywood?
Windsor Plywood carries finishing lumber in pine, poplar, hemlock, oak, maple, and MDF-based profiles. Poplar and pine are cost-effective choices for painted applications. Oak and maple are preferred for stained or natural finishes. Hemlock is a strong, stable option that takes paint well and is commonly used for trim in western Canadian construction.
What does S4S mean in finishing lumber?
S4S stands for Surfaced Four Sides, meaning the lumber has been planed smooth on all four faces. This is the standard for finishing lumber used in trim and millwork applications. The result is a consistently smooth, flat surface ready for priming, painting, or staining without additional preparation beyond light sanding.
What grade of finishing lumber should I use for painted trim?
For painted applications, select a paint-grade or finger-jointed product in pine, poplar, or MDF. These are designed for opaque finishes and are more affordable than clear-grade solid wood. Finger-jointed lumber uses shorter pieces joined end-to-end and is entirely appropriate for painted trim where the joints will not be visible.
How do I prevent finishing lumber from warping before and after installation?
Store finishing lumber flat on level supports in the installation space for at least 48 hours before cutting and fitting. This allows the wood to acclimate to the room's temperature and humidity. After installation, prime and paint all four faces including the back, which prevents differential moisture absorption that causes cupping and warping over time.