Plywood made from Douglas fir is a softwood plywood typically sold in 4-by-8 panels of varying thickness. Douglas fir is an evergreen common in many forested areas, and the plywood made from it is a common building product available in a range of grades and ratings for a variety of applications.
Douglas fir is an evergreen with long, soft needles. Many people display them as Christmas trees. Douglas fir timber is prized, as are many evergreens, for its resistance to rot. The trees grow quite large, making Douglas fir a good choice for large timbers for bridges, piers and similar types of construction projects. It is harder than average for a softwood and can be rough on power tool bits and blades. It has a straight grain and is average when it comes to shrinkage and warping as compared to other softwoods.
Douglas fir plywood has qualities that are typical of most plywoods. It has two outer facings, one known as the face and the other as the rear. The two outer layers, or ply, are always made of Douglas fir, and have their grain running vertically with the length of the sheet. The plies are laid, one atop the next, with glue in between in odd numbers. The outside and odd numbered layers run vertically, and the even numbered layers run perpendicular across the width of the sheet. Interior ply can be made of other species of wood, such as other varieties of fir, pine and cedar.
Douglas fir plywood comes in three basic grades. AB is as close to perfect as it comes. The outer layers are cut from a single sheet of veneer and should have no open knots and visible splitting or patches. BC grade is slightly rougher, with some open knots and minimal splitting. Visible patches are common. C grade varies the most, from very close to BC to open knots with voids and loose patching. The thickness and size of panels, along with their structural integrity should be consistent throughout all grades, with the main differences being cosmetic.
Douglas fir plywood is rated for both interior and exterior use, depending on the glue used in laminating the plies. More resilient, water-resistant glues are used in marine grades, which are sometimes used in boat construction. Interior uses range from sub flooring to roof decking. AB grade Douglas fir can be stained and finished with exposed grain, although it is not as commonly used in this way as hardwood plywoods such as Baltic birch. Cut Douglas fir plywood with a plywood blade to prevent the edge from fraying, although fraying may happen with any blade. If fraying occurs, the edge can be smoothed by using a rotary tool and a sanding band accessory.
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