About Plywood and Engineered Wood

Solid wood is wonderful to work with, but there are times when it isn’t the best choice, whether because of cost, design details or simply preference.

If you are working on an outdoor project there are several different types of manufactured wood replacements used for decking and other outdoor uses. These are made of various resins and have little or no real wood in them. Because they are manufactured the resins can be made specifically to resist rot. These composites often replace pressure treated wood. They are relatively new to the market, but are increasingly common.

Pressure treated wood is lumber that has been impregnated with chemicals that make the wood rot resistant. The wood is heavy and will last for years; however, exposure to the chemicals is dangerous. It’s best to use gloves and wear a mask if handling pressure treated wood.

Although pressure treated wood is becoming less toxic, people are switching to the resin wood replacements as a safer alternative. However, it’s still a good idea to use a mask if cutting any of the composite materials, because of the chemicals in the glues.

Other composite wood products include sheet goods such as particleboard, waferboard, and MDF (medium density fiberboard). These are all made of compressed wood particles of different sizes adhered together with various glues.

The results range from waferboard, which has large strands of recognizable wood, to MDF, which is made of wood that has been broken down almost to a powder. The advantage of these panels is that they are dimensionally stable because there is no grain direction. This is especially true of MDF which is heavy, stable and takes paint well.

Plywood is also more stable than solid wood. It is made of thin layers of veneer, also called plies, stacked so that the grain of one layer is perpendicular to the grain of the next.

Plywood comes in many grades and can have different materials for the core as well as the outermost veneer. The quality of the surface veneer determines the grade of the plywood. The grades range from A-D with A being the finest. Often plywood is graded on both sides, so you get one good side and one side with blemishes.

Furniture grade plywood is available in many different species and is often used in conjunction with solid wood. Manufactures use the finest grain patterns for the veneer and will book-match it along the panel.

On the other end of the plywood spectrum is construction grade plywood that is full of knots and voids. It is used mostly for adding rigidity to a frame or floor, etc.

Plywood is also graded either interior or exterior. The type of adhesive determines whether it will stand up to moisture or not. Don't try and use interior plywood outside, the ply's will separate. If you want something that will stand up to the worst types of weather, marine plywood is your best choice.

Marine ply is made of high quality materials bonded with a waterproof adhesive. Used in boat building it truly will stand up to the elements.

The moral of this story is that while solid wood is a wonderful medium, don’t forget the engineered woods. You can find just about anything you need, ranging from 1/8" thick plywood to engineered boards that are glued together to make a 40 foot long beam.

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