What is "roof glazing" and the "Patent Roof Glazing"? | |
in building construction
Answers:
1GLAZING. - The business of the glazier may be confined to the mere fitting and setting of glass (q.v.), even the cutting up of the plates into squares being generally an independent art, requiring a degree of tact and judgment not necessarily possessed by the building artificer. The tools generally used by the glazier are the diamond for cutting, laths or straight edges, tee square, measuring rule, glazing knife, hacking knife and hammer, duster, sash tool, two-foot rule and a glazier's cradle for carrying the glass. Glaziers' materials are glass, putty, priming or paint, springs, wash-leather or india-rubber for door panels, size, black.
There are several patent methods of roof glazing, such as are applied to railway stations, studios and printing and other factories requir ing light. Some of the first patents of this kind were erected with wood glazing bars; these were unsightly, since they required to be of large sectional area when spanning a distance of 7 or 8 ft., and also required to be constantly painted. This was a source of trouble ; the roof was constantly leaking and, moreover, it was not fire-resisting.
Of subsequent patents one includes the use of steel T-bars, in which the glass is bedded and covered with a capping of copper or zinc secured with bolts and nuts. Another employs steel bars covered with lead; and this is a very good method, as the bars are of small section, require no painting, and are also fire-resisting. There is one reason for preferring wood to steel, namely, that wood does not expand and contract like steel does. After the sun has been on steel bars, especially those in long lengths, they tend to buckle and then when cold contract, thus getting out of shape; there is also the possibility that when expanding they may break the glass. This is more noticeable in the case of iron ventilating frames in this glazing, which after having weathered for a year or two will begin to get out of shape and so give trouble in opening and closing.
Care should be taken not to fit the glass in iron bars tightly, but Water FIG. 2. - Section through Prism Pavement Light, the direction of light rays being indicated by arrows.
a good 8th in. play all round should be allowed
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