Plywood is a necessity in many DIY and construction projects, but not every type of plywood works for every project. This guide explains the different uses of plywood, sizes, materials and its rating and grade system so that you can choose the best plywood for your project.
Uses of Plywood
Plywood is an engineered wood from the manufactured boards family which includes particle board and oriented strand board (OSB). It is made from thin sheets of veneer peeled from debarked wood. These thin layers, also called plies, are glued together in alternating right angles to create a cross-grain pattern. This pattern adds strength and stability that resists shrinkage and expansion caused by moisture.
Plywood is a popular choice in construction because of its strength and low cost. It is used in areas hidden from view that offer support such as floors, walls, roofs and garages in residential construction.
When used for roofing, plywood panels are covered and protected by other materials that keep the elements at bay, including roof felt, underlayment, flashing and shingles. When used in flooring, plywood creates a sub floor that supports hardwoods, tile and carpet floors.
Stainable and printable plywood is ideal for shelving, cabinets and furniture. Outside the home, plywood can be transformed into fencing materials, packaging materials, scaffolding, sheds and shipping containers.
Common Types of Plywood
There are several common types of plywood:
Sanded plywood features face and back (top and bottom) plies that are sanded in the manufacturing process. It is used in places where it is visible, such as for cabinets, shelves and paneling.
Hardwood plywood is made from hardwoods like birch, maple and oak. The plies are glued at right angles to one another, making the plywood very strong and stable. It can be heavier than other types of plywood. Use hardwood plywood for furniture and anything that requires a strong load-bearing frame.
Plywood sheathing or structural plywood is designed for permanent structures. It is strong and inexpensive, but unfinished, and therefore not suitable for places where it will show. It should be covered by other types of materials. Use plywood sheathing for framing, beams, flooring and bracing panels.
Project plywood panels are ready-to-use, pre-cut plywood boards designed for quick and easy DIY projects. There are various types of wood, ply and plywood alternatives available. Use this for planned DIY projects when you know the measurements. It’s a great material for beginner DIYers.
Marker board has plywood panels with a coated writing surface to use with dry erase markers only. It is ideal for craft tables or finished marker boards.
Plywood Ratings, Grades and Sizes
Plywood is sold in various ratings, grades and sizes. Make your selection based on the type of project you’re working on.
There are five important ratings that convey where and how to use plywood: Exterior, Exposure 1, Exposure 2, Interior and Structural 1.
Exterior means the panels have been waterproofed and can withstand inclement weather. Use exterior rated plywood for permanent outdoor structures that will be exposed to water long-term.
Exposure 1 means the panels have been waterproofed and can withstand exposure to the elements during construction. However, they are not suitable for long-term exposure post-construction.
Exposure 2 means the panels are made with an intermediate glue that is not fully waterproof. These panels can withstand occasional moisture but are otherwise intended for interior use.
Interior means the panels are not waterproof and are designed for interior use only. They should not be exposed to moisture.
Structural 1 is rated for seismic retrofit work, meaning it is designed to be earthquake resistant. Unless they have a Structural 1 rating, other plywood panels of any width are not suited for seismic retrofitting.
There are four grades of plywood: A, B, C and D. The grade refers to the quality and appearance of the plywood’s face and back veneers. A has the highest quality and is the most expensive, and D is the least expensive.
A-grade plywood features a smooth, sanded
surface without knots. Any wood defects have been repaired with
synthetic filler, so the veneer can be painted. A-grade plywood is ideal
for furniture or cabinet doors.
B-grade plywood also features a smooth, sanded surface, but may have more repaired defects up to 1-inch across.
is unsanded and may have several minor defects that will need to be
repaired with knots up to 1 1/2 inches across, discoloration and sanding
defects. C-grade plywood should be used when appearance is not
important, such as for subfloors or garages.
D-grade is also unsanded with defects that have not been repaired and knot holes up to 2 1/2 inches across, discoloration and sanding defects.
You may also find ratings with two-letter classifications, such as BC. BC-grade is a mix grade plywood with one side graded a B, while the other side is graded a C.
The most common plywood sizes are 4- x 8-feet sheets and 5- x 5-feet sheets.
Most places also carry pre-cut project panels that are available in different sizes that may vary by store. These project panels help eliminate waste, cut costs and are easier to transport than full-size panels.
The most common thickness of plywood is 1/2-inch, but plywood thickness can range from 1/8-inch to 3/4 inches.