2 INTRODUCTION 



The building is firmly braced transversely by means of bracing in 

 the planes of the upper and lower chords and in the end bents, and 

 longitudinally by means of bracing in the sides and in the planes of the 

 upper and lower chords. 



The roof covering is supported on steel purlins placed at right 

 angles to the trusses and rafters. The side covering is fastened to 

 horizontal girts which are fastened to the side and end posts. Where 

 warmth is desired the roof and sides are lined. 



Steel frame mill buildings are usually covered with corrugated 

 iron or steel fastened to sheathing or directly to the purlins and girts. 

 Expanded metal and plaster, or wire netting and plaster has been used 

 to a limited extent for covering the sides and for sheathing the roof, 

 and will certainly be much used in the future where permanent struct- 

 ures are required. In the latter case slate or tile roofing is commonly 

 used. 



The buildings are lighted by means of windows in the side walls 

 and the clerestory of the monitor ventilator shown in Fig. i, or by 

 means of windows in the side walls and skylights in the roof. Ventila- 

 tion is effected by means of the monitor ventilator shown in Fig. I or 

 by means of circular ventilators. Where glass is used in the clere- 

 story of monitor ventilators the sash are made movable. The glass in 

 the clerestory of monitor ventilators is often replaced by louvres which 

 allow a free circulation of air and keep out the storm. In foundries and 

 smelters the clerestory is often left entirely open or is slightly protected 

 by simple swinging shutters. 



2. Steel Mill Buildings with Masonry Filled Walls. In mill 

 buildings of this type part of the bracing in the side walls is usually 

 omitted and the space between the columns is filled with a light wall of 

 brick, stone, concrete or hollow tile. The construction of the roof and 

 other constructional details are essentially the same as for steel frame 

 mill buildings. Buildings of this type are quite rigid and are usually 

 somewhat cheaper than type (3). 



