Plywood choice is by no means a universal architect’s choice. Each project has different needs such as load-bearing capacity, exposure to moisture, finish etc. There are grades and thicknesses, and before determining which of these to use, it is important to consider where the plywood will be used, what load it must support, and what surface treatment it must withstand. If these fundamentals are not right, it leads to costing rework and compromising down the line.
Grades and What They Mean in Practice
Plywood is produced in several grades and each will either affect or govern the use for a particular purpose and/or location. Exterior grade plywood is made with adhesives that are able to cope with moisture and are appropriate for facades, balconies and exterior shuttering. Interior grade varieties are suitable for cabinetry, panelling and false ceilings in dry climate controlled areas. The same adhesive bond strength as the plywood should always be used by the architect for the actual exposure conditions of the space, and not only for visual conditions.
Thickness Selection Based on Application
The thickness of the plywood is an important factor for the structural performance of plywood. In these areas, such as flooring and heavy duty shelving, thickness is required and can be achieved by buying sheets that range between 18mm to 25mm. Medium thickness of 12mm to 16mm provides a balance of rigidity and workability for furniture shutters, partitions and wall paneling. Thin plywood ranging in thickness from 4mm to 6mm is excellent for curved surfaces, decorative pieces and lightweight interior features where flexibility is important.
The Role of Core Construction
The quality and integrity of the interior of a plywood sheet has a significant impact on performance. A constant veneer core provides an even surface and is best for structural and furniture use. Combination core plywood, which is a mix of veneer layers and blockboard or MDF core, offers dimensional stability and is often used for cabinets and modular furniture. If plywood is being used for precision joinery, interior architects on high end interiors should be sensitive to the core voids and delamination concerns.
Moisture and Humidity Considerations
An incorrect specification of plywood is often the result of a guess on moisture exposure. High humidity occurs routinely in bathrooms, basements and kitchens, as well as in covered outdoor spaces. The dependable material to use in such spaces is the boiling waterproof grade, or BWP grade, plywood. It will maintain its structural integrity for extended periods of contact with moisture. BWP grade options are available for Duroply, which may appeal to architects looking to create space in areas with high moisture requirements.
Surface Finish and Workability
Plywood selection is also determined by surface finishes desired. Plywood meant for paint or laminate application needs a smooth, void free face veneer. Wood veneer finishes on sheets come in a variety of natural finishes and for natural wood veneer finishes to be consistent, grains need to be matched and the material used should be from one consistent batch of sheets. The architects should select plywood with higher surface hardness and scratch resistance if it will be used on high traffic surfaces. Workability is important as well because sheets that don’t hold screws and nails well will cause the final installation to have less durability.
Bottom Line
The specification for plywood should be a technical rather than a procurement decision. Architects that interact with a grade chart, IS standards, and manufacturer specifications early in the design process consistently bring better results. From structural to decorative and functional applications, the specific type of plywood for specific environments will help buildings operate as intended, for years to come.