The Viaduct Works' Handbook

A great improvement upon these last-mentioned roofs is seen in the framing shown in the following sketch, consisting of T iron ribs with “purlins” of angle iron, to which corrugated iron is fastened by hooked bolts. This framing, in the simple form here shown, is effective for roofs up to 60 feet span with slight modification of the trussing. Many such roofs, manufactured at the Viaduct Works, have stood in a most satisfactory manner, where others of the last-mentioned description have been known to fail. The following table of approximate prices of roofs of this class may be found useful, the price being per square of 100 superficial feet measured over the roof:— Iron framework for roof, without ventilator, per square ......................................... Painted corrugated iron covering, 16 B.W.G., per square . . . . . . . Painted corrugated iron covering, 14 B.W.G., per square....................................... Add extra for ventilator framework, per square, on the portion ventilated .... If galvanized. £ s. d. £ s. d. 3 17 2 2 14 1 3 12 1 361 491 2 12 0 The cost of iron sheds, consisting of iron roofs supported on pillars and girders, such as that shown on next page, may be arrived at by reference to the tables already given for the prices of roofs of different kinds and widths of span, with the addition of the cost of the pillars or columns and girders. The pillars are of a simple kind of stanchion, of a cross section, in height about 12 feet, weighing about 2 cwt. each. The centre girders between them are 20 feet long, and weigh about 54 cwt. each. The —