Fig. 23
The only exception to effective bracing being carried out is where the building, being of irregular form, creates many breaks and returns in the scaffolding. It is obvious that where a scaffold butts against or breaks with a return wall, the tendency to lateral motion is lessened.
The boards, which are placed longitudinally across the putlogs, can be laid to lap or butt at their ends. When lapping, one putlog only is required to carry the ends of two series of boards ([fig. 22]).
When butting, two putlogs are required placed about 4 inches apart ([fig. 23]).
The second method is the better, as the boards are not so likely to lose their place or to trip the workmen. If heavy work is in progress the boards are laid double. As the building rises, the boards are carried up to each successive platform, but each tied putlog is left in its place.
Fig. 24.—Masons’ Scaffolds: End Elevation
Masons’ Scaffolds.—Masons’, or independent scaffolds differ from the bricklayers’ in that they have to be self-contained. Owing to the different material of which the building is erected, the putlogs cannot rest upon the wall. If openings were left for them, as in brickwork, the wall would be permanently disfigured, more especially when ashlar fronted.
In order to gain the necessary support two parallel frames of standards and ledgers are erected along the line of wall to be built ([fig. 24]).