The types of plywood are categorized based on grade, type of wood, strength and special features. The ideal plywood for a particular project depends on the intended application as well as the preference of the builder.
Plywood is used both indoors and outdoors for construction, carpentry, sign making, furniture and a variety of other applications. The different categories of plywood include:
- Grade - Plywood is rated A, B, C or D based on the number of knotholes, the smoothness of the grain and the acceptable uses.
- Strength - The strength of a sheet of plywood is expressed in the type of ply, such as 3-ply, 5-ply or multi-ply, with larger numbers indicating stronger plywood that can be used for heavy-duty applications.
- Type of wood - Hardwood and softwood are the two most common types of plywood, though tropical wood is also a popular choice because it is less expensive.
- Special features - Some forms of plywood are pressure-treated, fire-retardant or made for a specific application; for example, marine plywood is engineered to withstand high levels of humidity and moisture.
Plywood should not be confused with alternative materials that serve similar functions, such as particleboard, fiberboard or hardboard. Medium-density fiberboard, or MDF, for example, has become popular for construction and furniture due to its low cost.