Composite wood is a mixture of several components that may include wood, plastic and straw. The particles and fibers from different woods are combined, and adhesives keep them bound together. A veneer is often applied to the outside in order to make the composite wood appear more attractive. Composite woods are often used in cabinets, furniture, sheathing, flooring and siding. They are less expensive than hardwood, and they are also weather-resistant when they have been painted or sealed. Some companies avoid building with composite wood because it requires more energy during production. It may also contain harmful chemicals due to the substances that are used to mix and bind the wood particles.