GB405044A - Improvements in or relating to the construction of staircases - Google Patents

Abstract

405,044. Staircases. NORRIS, F. A., 11, St. Andrews Hill, London. Aug. 8, 1932, No. 22201. [Class 20 (iv).] Relates to metal staircases of the kind in which each riser 13 is integral with the tread 14 next above it. According to the invention, the lower edge of each riser is bent inwardly and outwardly as shown at 15, 16 and the rear edge of each tread is bent upwardly as at 17 to enable the bent edges 16, 17 of adjacent treads and risers to be secured together and to the lower flanges 11 of the stringers 10, and a supplementary tread 25 is maintained in position on each tread 14 by its rear edge engaging the recess formed by the co-operating bent edges of an adjoining tread and riser and also by means positioned at or near the front of the tread. The stringers are of Z-shape in cross-section, and the edges 16, 17 of the treads and risers are secured to the lower flanges of the stringers by bolts or rivets 21. An anglebar 18 is secured beneath each tread by bolts or screws 27 and is connected between the stringers by bolts, rivets, or welding. The supplementary tread 25, which may be in the form of a pre-cast concrete slab as shown in Fig. 1, may be secured at the front edge of a tread 14 by a nosing 22 of channel shape which is secured by screws or bolts 23 to the anglebar 18. A removable nosing 26, having a non-slip surface, may be mounted on the extended upper flange of the nosing 22 and bolted or screwed to the angle-bar 18. When the supplementary tread is of wood, marble &c., it may be secured by bolts or screws 27 to the angle-bar 18, as shown in Fig. 2. The bent edges of the treads and risers may be provided with a series of holes for supporting lattice work or expanded metal lathing to enable the rear of the staircase to be plastered. Angleshaped strips to key with the plaster may also be secured to the lower flanges of the stringers.