In addition to grading, plywood is also rated for where it should be used and the ability to withstand moisture.
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Exterior: These panels are waterproofed to tolerate adverse weather conditions. Exterior rated plywood is used on outdoor buildings that will be exposed to the elements.
Exposure 1: These panels have been waterproofed but only for the construction period. They are not manufactured for extended exposure like exterior panels are.
Exposure 2: The plies in this plywood have a transitional adhesive that is not designed for long-term water exposure and thus not fully waterproof. Occasional exposure is okay, but Exposure 2 panels are best for interior use.
Interior: These panels have no waterproofing at all and should not be exposed to moisture. They are intended for interior use only.
Structural 1: These panels are constructed to be earthquake resistant and are rated for seismic retrofitting. Only Structural 1 panels can be used in this type of construction work.
Exterior plywood is used outside the home where durability is required. Bound together using water-resistant glue that doesn’t wear off easily, this plywood is wind and weather resistant. Some of the most suitable applications for exterior plywood are walls, roof linings, and outdoor structures.
Interior plywood is not very resistant to outdoor elements and tends to degrade quickly when exposed to moisture and heat. Some of the popular applications for interior plywood include indoor furniture, interior cladding, and craft projects. Check out our article Simple DIY Plywood Projects to Upgrade Your Home for great ideas to make.
Plywood sheathing and OSB (Oriented Strand Board) are both universally used structural panels in construction, especially for walls, roofs, and subfloors. Here’s a breakdown of their key differences:
Material Composition: Plywood sheathing is made from thin layers or plies of wooden veneer glued together. OSB is made from wood strands compressed and bonded together in a crossways-oriented configuration.
Strength: Plywood is stronger overall, impact resistant and better able to hold nails and screws. OSB is comparable strength-wise, but the edges can swell when exposed to moisture.
Moisture: Plywood can withstand water better as it dries faster and is less likely to swell and warp. OSB will absorb water more slowly but will retain it longer if not adequately sealed.
Appearance: A smooth and uniform surface are features of plywood. OSB has a rougher, chip-like appearance that is typically left unfinished and hidden from sight.
Cost: Plywood is usually a bit more expensive due to the manufacturing process and better materials. OSB is more budget-friendly, making it a popular choice where costs are concerned.
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 subfloor that supports hardwoods, tile and carpet floors.
Stainable and paintable 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.
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.
Markerboard has plywood panels with a coated writing surface to use with dry erase markers only. It is ideal for craft tables or finished markerboards.
Are you interested in learning more about 4x8 roofing plywood? Contact us today to secure an expert consultation!
A ply refers to a layer of veneer used to create plywood’s various thicknesses. More ply creates a thicker and stronger board. Plywood has an odd number of plies and needs at least three plies. Although specialty plywood can have any number of plies above three, most plywood is categorized as 3-ply, 5-ply or multi-ply.
3-ply is one of the most common types of plywood. It is about 2- to 3-millimeters thick and is generally used indoors, since it looks more decorative than thicker plywood boards.
5-ply is a versatile type of plywood that is about 4-millimeters thick. Use it indoors or outdoors, but avoid using for framing permanent structures, such as a shed or a home.
Multi-ply is a catchall term for plywood with seven or more plies. This plywood is strong and durable enough for use in roofing, framing and other exterior, structural projects.
Tip: Plywood with fewer plies is weaker than a plywood with more plies, even if they have the same thickness.
Plywood is sold in various ratings, grades and sizes. Make your selection based on the type of project you’re working on.
Plywood Ratings:
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.
Plywood Grades:
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.
C-grade 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.
Plywood Sizes:
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.