In large roofs, especially those which are subject to vibration, as in the case of railway stations, or those subject to hot fumes such as arise from some workshops, it is desirable to avoid the use of putty, which becomes dried and loose, and is shaken out so that leaks are caused in the roof.
Every good system of glazing without putty should have the following characteristics.
a. It should be simple in construction, so as to be easily repaired by ordinary workmen. Broken panes should be easily replaced.
Of late years many systems of glazing have been introduced in which the use of putty is altogether avoided.
Of those now in use the principal forms are shown in Plate XIII. The writer has had most of these forms tried. He prefers, however, not to make any invidious comparison between them. Sometimes a system not suitable for one structure is suitable for another.
1 Seddon's Builders' Work.