22.B.09 Design.
- The dimensions of the members and materials used in the construction of various working platforms or scaffolds must conform to the sizes shown in the ANSI A10.8 tables.
Wraparound Scaffold
- Factory-fabricated scaffolds and components must be designed and fabricated in accordance with the applicable ANSI standard. When there is a conflict between the ANSI standard and this manual concerning the design or fabrication of factory-fabricated scaffolds, the ANSI standard must prevail.
- Load-carrying timber members must be a minimum of 1,500 lb-f/in2 (10,342kPa) (stress grade) construction grade lumber.
- All dimensions are nominal sizes (except where rough sizes are noted) as provided by Voluntary Product Standard DOC PS20, published by NIST of the US Department of Commerce.
- Where rough sizes are noted, only rough or undressed lumber of the size specified will satisfy minimum requirements.
- Lumber must be reasonably straight-grained and free of shakes, checks, splits, cross grains, unsound knots or knots in groups, decay and growth characteristics, or any other condition that will decrease the strength of the material. > For planking, see Section 22.B.15.
- When scaffolds are wrapped with tarps, poly enclosures, or similar materials; wind calculations will be calculated by a Qualified Person (QP) to determine the strength and placement of the ties.
22.B.10 Supporting members and foundations must be of sufficient size and strength to safely distribute loading.
- Supporting members must be placed on a firm, smooth foundation that will prevent lateral displacement.
- Unstable objects such as barrels, boxes, loose bricks, or concrete blocks must not be used as supports.
- Vertical members (i.e., poles, legs, or uprights) must be plumb and securely braced to prevent swaying or displacement.
22.B.11 The design and construction or selection of solid wood planking and platform for means of access must be based upon either the number of persons for which they are rated or the uniform load distribution to which they will be subjected, whichever is the more restrictive.
22.B.12 Scaffolds must be plumb and level unless engineered and designed to contour as the structure does.
22. B.13 Scaffolds (other than suspended scaffolds) must bear on base plates upon mudsills or other adequate firm foundation.
22.B.14 Working levels of work platforms must be fully planked or decked.
Knowledge Check Choose the best answer for the question.
22-3. What is the requirement for the quality of load-carrying timbers for scaffolds?
You forgot to answer the question!