Plywood

Plywood is a sheet material manufactured from thin layers or "plies"

of wood veneer that are glued together with adjacent layers having

their wood grain rotated up to 90 degrees to one another. It is an

engineered wood from the family of manufactured boards which

includes medium-density fibreboard (MDF) and particle board

(chipboard).

Types of plywood

Other types are... 

Softwood plywood: Softwood panel is usually made either of cedar , Douglas fir or spruce,

pine, and fir (collectively known as spruce-pine-fir or SPF) or redwood

and is typically used for construction and industrial purposes.

Hardwood plywood: is made out of wood from angiosperm trees and

used for demanding end uses. Hardwood plywood is characterized

by its excellent strength, stiffness and resistance to creep. It has a

high planar shear strength and impact resistance, which make it

especially suitable for heavy-duty floor and wall structures. Oriented

plywood construction has a high wheel-carrying capacity. Hardwood

plywood has excellent surface hardness, and damage- and wear-

resistance. 

Tropical plywood: is made of mixed species of tropical wood.

Originally from the Asian region, it is now also manufactured in

African and South American countries. Tropical plywood is superior to

softwood plywood due to its density, strength, evenness of layers,

and high quality. 

Aircraft plywood: High-strength plywood also known as aircraft plywood, is made from

mahogany and/or birch, and uses adhesives with increased

resistance to heat and humidity. It was used for several World War II

fighter aircraft .

Marine plywood: is manufactured from durable face and core veneers,

with few defects so it performs longer in both humid and wet

conditions and resists delaminating and fungal attack. Its

construction is such that it can be used in environments where it is

exposed to moisture for long periods.

Other plywoods: Other types of plywoods include fire-retardant, moisture-resistant,

wire mesh, sign-grade, and pressure-treated. However, the plywood

may be treated with various chemicals to improve the plywood's

fireproofing. Each of these products is designed to fill a need in

industry.

Sizes

The most commonly used thickness range is from 0.14 to 3.0 inches

(0.36 to 7.62 cm). The sizes of the most commonly used plywood

sheets are 4 by 8 feet (1.2 by 2.4 m). Width and length may vary in

1-foot (30 cm) increments.

In the United States, the most commonly used size is 4 × 8 feet

(1,200 × 2,400 mm) or 5 × 5 feet (1,500 × 1,500 mm). [9] A common

metric size for a sheet of plywood is 1,220 × 2,440 millimetres

(4.00 × 8.01 ft).

Sizes on specialised plywood for concrete-forming can range from 6

to 21 mm (0.24 to 0.83 in), and a multitude of formats exist, though

15×750×1,500 mm (0.59 inch × 2.46×4.92 ft) is very commonly used.