Suspended Scaffolds » Single-point Adjustable

Single-point Adjustable

A single-point adjustable scaffold consists of a platform suspended by one rope from an overhead support and equipped with means to permit the movement of the platform to desired work levels. The most common among these is the scaffold used by window washers to clean the outside of a skyscraper (also known as a boatswain's chair).

NOTE: The requirements on this page are specific to single-point adjustable scaffolds only. For requirements that apply to all types of suspended scaffolds, please refer to the Two-point (swing stage) module.


The maximum intended load for these single-point adjustable suspension scaffolds is 250 lbs. [29 CFR 1926 Subpart L Appendix A (o)]

  • Boatswain's chair tackle must consist of [29 CFR 1926.452(o)(3)]:
    • Correct-size ball bearings or bushed blocks containing safety hooks.
    • Properly eye-spliced first-grade manila rope, or other rope of equivalent strength, durability, etc.
  • Seat slings must:
    • Pass through four corner holes in the seat.
    • Cross on the underside of the seat.
    • Be rigged to prevent slippage which could cause the chair to be out-of-level. [29 CFR 1926.452(o)(4)]
    • Be at least 5/8-inch diameter fiber, synthetic, or other first-grade manila rope of equivalent criteria (strength, slip resistance, durability, etc.). [29 CFR 1926.452(o)(5)]
  • Seat slings used for gas or arc welding must be made of at least 3/8-inch wire rope. [29 CFR 1926.452(o)(6)]
  • Non-cross-laminated wood chairs must be reinforced on the underside with cleats to keep the board from splitting. [29 CFR 1926.452(o)(7)]

Non-mandatory guidelines from 29 CFR 1926 Subpart L Appendix A:

  • Wood seats for boatswain's chairs must be [29 CFR 1926 Subpart L Appendix A (o)]:
    • Not less than 1-inch thick (if made of non-laminated wood), or
    • 5/8-inch thick (if made of marine-quality plywood).