Even if the collective term plywood can quickly tempt you to lump together every material that fits this description, the following still applies here: plywood is not just plywood! Above all, three specific types of plywood are widespread in everyday construction but differ significantly in their production method and properties. We now want to take a closer look at these three types of plywood. In this article, we present how they are structured and what makes them unique.
The three most important types of plywood do not initially differ according to the types of wood processed, but mainly according to the principle of their industrial production. In the case of cross-laminated timber, for example, the individual layers (three to seven) are each layered at an angle of 90 ° (in exceptional circumstances 45 °) along the direction of the grain and then connected with synthetic, formaldehyde-free glue. Instead of particularly high-quality heartwood, the side zones of the trunks can also be processed, which nevertheless leads to excellent material values in terms of rigidity and strength.
The main area of application is the rustic and mostly very solid panels made of cross-laminated timber in residential and commercial buildings, where they are particularly valued because of their high fire resistance. Other possible uses are in the context of energetic building renovations, as many of the commercially available insulating materials can be attached to this type of plywood with excellent results.
Wall and ceiling cladding, as well as furniture made from molded or veneer plywood panels, are more expensive to manufacture, but also extremely malleable. For this purpose, an uneven number of veneer panels are glued together at temperatures between 160 and 180 ° C under high pressure and then not flat, but instead pressed into shape according to the final product. Due to its high dimensional stability, veneer plywood is ideal for use in the furniture industry as well as in the construction industry. Perhaps you’ve only just sat down on a plywood seat on public transport or installed a new plywood worktop in the kitchen?
Thanks to simple further processing options and the very good material values in terms of dimensional stability and moisture resistance, this representative of the plywood types have a particularly wide range of applications, ranging from the construction and furniture industries to the automotive and rail vehicle industries. Besides, the durable and temperature-resistant natural wood is very suitable for use in cool, damp, and wet outdoor areas.
Another form of production is offered by plywood, which is considered to be extraordinarily moisture-resistant and dimensionally stable. For this purpose, wooden strips or rods arranged in parallel are glued on both sides with barrier veneers that are perpendicular to them. The middle layer enclosed in this way is correspondingly massive. In the case of stick plywood, on the other hand, the middle layer consists of thin strips of veneer, which are arranged and glued perpendicular to the plane of the board. With this technology, shrinkage and swelling movements can be almost completely ruled out, which makes the stick plywood panels a little more expensive, but significantly higher quality.
Rod plywood comes very close to the quality of hardwood and can be processed in the same uncomplicated way, especially in the furniture industry and interior construction. Other areas of application include vehicle and caravan construction thanks to its low weight. We even encounter the stick plywood panels, which also look very high-quality, as decorative cladding in the ship’s cabins or on the sun deck when we are on our way to relax on the oceans.
A question of quality
In the end, of course, the wood used comes into play. The selected starting material, i.e., the type of tree used, is an essential factor for the later quality of the end products for all three types of plywood. Poplar, beech, birch, or West Indian mahogany have very different properties in terms of flexibility, elasticity, moisture resistance, resilience, and weight. And they also differ significantly in terms of appearance. It is, therefore, worthwhile to go into this again separately in another article.
We also recommend all do-it-yourselfers who are interested in more detailed facts about the properties of plywood and who might soon want to use this environmentally friendly natural building material in their own four walls to visit the online portal of the carpenter and vocational school teacher Ole Welzel. Among other things, the most important information on the current DIN and EN standards can be downloaded there, which should be quite helpful for your construction planning.