Plywood is a wood product that consists of thin layers – usually three or more – glued together. It is often used for building floors, walls, roofs and sub-floors because it can be easily molded into different shapes, it’s inexpensive to make, durable and plentiful in supply. Plywood is also relatively simple to work with if you know what you are doing. Unfortunately, because plywood comes in contact with water on a frequent basis during its lifetime as a flooring material or whatever purpose it serves, there exists the possibility for delamination (or separation) of the individual layers of wood that comprise the structural core.
Plywood has an adhesive applied between each layer known as resin glue . Resin glue forms stronger bonds than wood glue and is the main reason plywood is used in construction. Plywood is made up of an odd number of layers so that when the wood expands and contracts (a natural occurrence with changes in humidity), the layers move in opposite directions, thus minimizing the chances of delamination. Plywood is graded according to its quality based on the number of defects (such as knots) and the thickness of each layer. The best quality plywood has no defects and all layers are at least 1/32 inch thick.
Plywood can delaminate for a variety of reasons such as water damage, improper storage, poor construction or installation, high levels of moisture in the environment, etc. Once plywood delaminates it becomes structurally unsound and should be replaced. There are, however, ways to prevent plywood from delaminating in the first place.
The main way to prevent plywood delamination is to make sure it is properly stored and protected from the elements. Plywood should always be stored on a flat surface in a dry environment. When transporting or installing plywood, avoid exposure to moisture and use protective coverings such as tarps or plastic sheeting. If plywood gets wet, allow it to air dry completely before using it or storing it away again.
In addition, be sure that the adhesive between the layers of wood is applied evenly and that there are no voids (spaces) between the layers. Any defects in the wood such as knots, bumps or craters create stress points that are likely to cause delamination. Plywood should also be nailed or screwed tightly together at all edges where two pieces come in contact. Plywood can also be layered with metal for added strength and durability if necessary.
If you suspect there is a problem with your plywood flooring you can usually tell by inspecting it. Plywood delaminates when moisture causes the glue between layers to break down and separate. If this has happened, the plywood will feel spongy underfoot, sound hollow when tapped or bounce back into place after being depressed – just like a sponge .
The best way to repair plywood that has already delaminated is to remove any nails, screws or staples that are holding it together and then re-glue the layers back together using a high-quality wood glue. Plywood that is in good condition can be fixed by simply injecting the glue between the layers using a caulking gun . In either case, make sure the surface is clean and free of dirt, dust and other debris before starting.
Plywood is a great building material when it’s used correctly and taking a few simple precautions can help keep it in good condition for years to come. By following these tips, you can help prevent Plywood delamination and ensure your plywood projects are both structurally sound and beautiful.