(1) You must make sure roof carriage system stability is obtained by using gravity, attachment to a structural support, or a combination of gravity and structural attachment.

(2) You must never use a material that can flow as a counterweight to achieve stability.

(3) You must make sure the stability factor against overturning for horizontal traversing of the carriage, including wind and impact effects, is not less than two.

(4) You must make sure carriages and their anchorages can resist accidental over-tensioning of the wire ropes suspending the platform. Include in the calculation the effect of one and one-half times the stall load of the hoist.

(5) You must make sure all parts of the powered platform installation can withstand, without damage, the forces resulting from a load equal to the stall load of the hoist and one-half of the wind load.

(6) You must make sure roof carriages which develop the required stability against overturning by using tie-down devices secured to the building have an interlock which will prevent vertical platform movement unless the tie-down is engaged.