When taking off and pricing glass, an estimator must consider:
if the specifications call for double glazed; if so, twice as many square feet of glass will be required for a particular opening.
that glass is generally available only in single strength, and to obtain double strength, two panes of glass are required.
that glass for doors with windows does not need to be taken off separately as the glass always comes with the door.
that the price for glass is strictly a function of the thickness and should be grouped by thickness for estimating purposes.