Last Updated Oct 22, 2010 · Written by Craig Gibson
Plywood is a versatile building material that has a multitude of applications in all areas of the home. But what exactly is plywood and what different types are there? Read on for our guide to plywood.
Plywood is a manufactured board that is made up of an odd number of thin sheets of wood – called plies or veneers – that are glued together under heat and pressure. The odd number is so that the top and bottom sheet have the grain facing the same way. Each sheet of wood has the grain going lengthways on one layer and crossways on the next and so on. This is what gives plywood its strength. Plywood is strong in all directions where standard wood is only strong across the grain. It can be made from softwood or hardwood. Plywood can be used for many things including flooring, wall panels, bracing, furniture, cabinetry, formwork, and so forth.
Plywood is available in different grades, with A being the highest grade and D being the lowest grade. If the plywood is designed to be seen, it will have an A grade front face, and a D grade back face. Plywoods that are not going to be seen usually use lower grades, such as a C grade front and a D grade back.
There are several different types of plywood that you can use, depending on what your project is. The types of plywood are:
• Interior – this can be made from hardwood or softwood and is used on the interior of the home, such as in wall lining, furniture, door skins, and in ceilings. Several different faces are available depending on the look that you are after. Interior plywood is available in most grades.
• Exterior – is high quality and it is a non structural type of plywood. It can be used in full or semi exposed areas. There are several different types of faces available depending on your needs. The glue in exterior plywood is much more moisture resistant. Nearly all grades of plywood are available.
• Marine – this is the type of plywood to use when you need it to be moisture resistant. This type of plywood uses the best glues and is the best manufactured.
• Structural – is used when the strength and the stability of the plywood is the primary concern more so that the appearance of the plywood. In this type of plywood, the glues are designed for maximum strength so that the layers do not separate.
There are several advantages to using plywood in your building project. These include:
• Resistance to splitting and warping
• Its ability to be shaped into different forms
• Comes in standard sizes
• Is very cost efficient
The wood that is used to make plywood comes from sustainable forests. In addition, many manufacturers replant more trees than they actually use in the manufacture of the plywood. One concern with plywood has been the glues that are traditionally used – such as synthetic resins and formaldehyde based glues that can cause off gassing. As there has been more pressure on manufacturers to find greener solutions in their manufacturing, there are more environmentally friendly glues and adhesives being used.