gang boarding

cat ladder, duckboard, gang boarding, roof ladder

cathedral: plan of Wells Cathedral. A, apse; B, altar; D, E, eastern transept; F, G, western transept; H, central tower; I, J, western towers; K, north porch; L, library; M, western doorway; N, N, western side doors; O cloister yard; P, Q, north and south aisles of choir; S, S, east and west aisles of transept; T, U, north and south aisles of nave; R, R, chapels; V, rood screen; W, altar of lady chapel
A plank with a series of small strips nailed across it; hung on a sloping roof under repair to provide a footing for workmen and to protect the surface.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.