glazing sheets speaks to what are plastic glazing sheets, why use plastic glazing sheets.
These are transparent plastic sheet materials which are often used instead of glass for specialized glazing applications.
The two most common plastic glazing materials are acrylic and polycarbonate. Both are more expensive than ordinary float glass. Both have very high coefficients of thermal expansion, which cause them not merely to expand and contract with temperature changes, but also to bow visibly toward the warm side when subjected to high indoor, outdoor temperature differentials.
This, in turn, requires that plastic sheet materials be installed in their frames with relatively expensive glazing details that allow for plenty of linear movement and rotation. Both polycarbonate and acrylic are soft and easily scratched, although more scratch resistant formulations are available.
Plastic glazing is most commonly used where glass is inappropriate. Plastics can be cut to shapes with inside corners, such as L shapes and T shapes, that are likely to crack if cut from glass. They can be bent easily to fit in curved frames. They can be heat formed into domed glazing for skylights.
As well, the plastics especially polycarbonate, which is literally impossible to break under ordinary circumstances, are widely used for windows in buildings where vandalism is a problem or high impact resistance is required.
Polycarbonate plastics can be manufactured in a double wall configuration called cellular polycarbonate glazing creating hollow panels roughly one quarter inch to one and a half inches (6-40 mm) thick with greater stiffness and better thermal performance than solid sheets. Plastic sheets can also meet safety requirements for glazing used in areas subject to human impact.
Translucent but nontransparent plastic sheets reinforced with glass fibers known as fibreglass reinforced polyester glazing are used for industrial skylights and residential patio roofs. Thin flat sheets of a special formulation with a high translucency to solar energy are used for skylights and low cost solar collector glazing.