glass
Roofing made of glass, either as an opaque coating or in the form of an extended skylight.
A glass roof is any sheltering upper layer of a building whose outer surface is primarily glass, whether the glass coats an opaque surface or serves as a transparent or translucent roof. Almost all glass roofs, if the structure has significant size, include a framing system of metal, wood, or other material. Most glass roofs are essentially skylights which cover a major extent of the roofing surface.
Glass is the principal outer covering even where another material provides the supporting frame. Transparent glazing and glass over an opaque surface are both included.
Fiberglass sheeting contains glass fibers within a plastic matrix and is a different material. A roof with an isolated skylight does not become primarily glass solely because that opening admits light.
