These general hints will help you achieve the best possible results in working with APA wood structural panel products. They apply not only to this plan but to all projects you may undertake using APA trademarked panels. Since building methods and interpretation of suggestions may vary, APA – The Engineered Wood Association cannot accept responsibility for results of an individual’s project efforts.
Before starting, study the plan carefully to make sure you understand all details.
Following the panel layout, draw all parts on the panel using a straightedge and carpenter’s square for accuracy. Use a compass to draw corner radii. Be sure to check the width of your saw cut and allow for saw kerfs when plotting dimensions.
When hand-sawing, support panel firmly with tile best side facing up. Use a 10 to 15 point cross-cut saw. Use a finetoothed coping saw for curves. For inside cuts, start hole with a drill and use a coping or keyhole saw. When power sawing on a radial or table saw, the best side of the panel should be face up. A plywood blade works best but a sharp combination blade may be used. When using a portable power saw, the best side of the panel should be down. For curved cuts, use a jigsaw, bandsaw or saber saw. Be sure the blade enters the face of the panel. Use the finest tooth possible for a smooth and even cut. For prolonged cutting of nonveneer panels and those containing layers of reconstituted wood, a carbide-tipped blade is suggested. Reduce panel to pieces small enough for easy handling with first cuts. Plan to cut matching parts with the same saw setting. Scrap lumber clamped or tacked securely in place beneath the panel prevents splintering on the back side.
Overlaid panels can be worked in the same manner as regular grades with these exceptions: sawing and drilling should always be done with the cutting
edge of the tool entering the panel face. To minimize chipping at the point of tool exit, use a piece of scrap wood as a backup or place tape along the line of the cut.
Support panel firmly. Use brace and bit for larger holes. When point appears through panel, reverse and complete hole from back. Finish slowly to avoid splintering.
Remember, edge grain of the panel runs in alternate directions so plane from ends toward center. Use shallow set blade.
Many APA panels are sanded smooth in manufacture – one of the big time-savers in their use – so only minimum surface sanding is necessary.
You may find it easier to sand cut edges smooth before assembling each unit. Use medium or finer sandpaper before sealer or flat undercoat is applied. Use fine sandpaper after sealing and in direction of grain only.
Construction by section makes final assembly easier. Drawers, cabinet shells and compartments, for example, should be handled as individual units. For strongest possible joints, use glue with screws or nails. Check for a good fit by holding pieces together. Contact should be made at all points for lasting strength. Mark nail location along edge of piece to be nailed. In careful work where nails must be very close to an edge, predrill using a drill bit slightly smaller than nail size. Always predrill for screws. Apply glue to clean surfaces according to manufacturer’s instructions. Press surfaces firmly together until bead appears. Check for square, then nail and apply clamps if possible to maintain pressure until glue sets. For exterior exposure, use resorcinol-type (waterproof) glue; for interior work, use liquid resin (white) or urea resin-type glues. Other glues are available for special gluing needs.
FINISHING FOR INTERIOR USE
Little, if any, surface preparation is usually required. Sanded panels require only light sanding to remove blemishes or to smooth fillers which might be used to patch any dents or openings in the surface. Sand in the direction of the grain only with fine sandpaper. If an opaque finish is to be used,
cover any knots, pitch streaks, or sap spots with shellac or a stain-resistant sealer. Do not apply finishes over dust, glue or spots of oil. Three types of finishing systems may be used for interior applications: paints, stains and natural finishes.
When using paint systems, a solvent thinned (oil-based) primer should be used to minimize grain raise and prevent staining. Gloss and semi-gloss enamel top coat provide a washable, durable surface. The top coat may be oil-based or alkyd-based (solvent-thinned) or latex (water-thinned), provided it is compatible with the primer.
Panels used for natural finishes should be carefully selected for pattern and appearance. For the most natural appearance, use two coats of a clear finish, such as a urethane, varnish or clear sealer. To pleasantly subdue any grain irregularities or repairs, a light stain finish may be applied either by color toning, which uses companion stain and non-penetrating sealer, or light staining, which uses a pigmented sealer, tinting material (stain, thin enamel or undercoat), and finish coat (varnish or lacquer). Finish Medium Density Overlaid (MDO) panels with a solid color acrylic latex stain or two-coat paint system (primer plus companion top coat).
FINISHING FOR EXTERIOR USE
A top quality stain or paint will help maintain the panel’s appearance and protect it from weathering. Since end grain absorbs and loses moisture apidly, panels should be edge-sealed to help minimize possible damage. Use paint primer to seal panels to be painted, or use a paintable water-repellent preservative for panels which are to be stained.
For rough or textured panels, either high quality stain or acrylic house paint systems are recommended. Use a solvent-thinned semi-transparent stain for maximum grain show-through. Use only acrylic latex solid-color stain when it is desirable to hide the grain and color of the wood surface, but not its texture. Maximum protection of the wood is obtained by using a house paint system which consists of a stain-resistant primer and one or more acrylic latex top coats. Finish Medium Density Overlaid (MDO) panels with solid-color acrylic latex stain or a two-coat paint system (primer plus companion top coat).
Best performance is achieved by applying the first coat of finish by brushing. If the first coat of finish is sprayed on, it should be back-brushed or back-rolled to work it well into the wood surface. Additional coats may be sprayed without back-brushing.
Whatever finishing method is used – paint or stain – always use top quality materials and follow the manufacturer’s instructions.
How to Buy APA Panels
APA trademarked panel products are manufactured in two basic types: panels for permanent exposure to the weather or moisture, and panels for interior or protected applications when only temporary exposure to moisture or the weather is required. Within each type are numerous grades – sheathing grades, panels with smooth sanded surfaces on one or both sides, textured panels and panels with overlaid surfaces. Panel recommendations for this plan are contained in the Materials List.
When selecting panels for your application, always look for the APA trademark. The mark signifies that the manufacturer is committed to APA’s rigorous program of quality supervision and testing and that panel quality is subject to verification through APA audit – a procedure designed to assure manufacture in conformance with APA performance standards and/or U.S. Product Standard PS 1-07 for Construction and Industrial Plywood.
Although every effort is made to be accurate in the design and drawing of all APA plans, the possibility of error exists. Be sure that you review and understand all steps of construction and verify all dimensions before cutting your material. Quality of workmanship and the conditions under which paneIs are used vary widely. Because the Association has no control over these elements, it cannot accept responsibility for panel
performance or designs as actually constructed.