November 25, 1997
Mr. Stephen Almony
217 South Burlington Road
Bridgeton, New Jersey 08302
Dear Mr. Almony:
This is in response to your fax transmission of September 4 to the Occupational Safety and
Health Administration (OSHA) in which you asked about the Agency's interpretation of several
issues that had been addressed in OSHA Program Directive #100-84, dated January 31, 1978. As
you noted, those interpretations applied to the old scaffold standard for construction, which
was revised in August of 1996. We appreciate your taking the time to communicate with the
Regarding superseded 29 CFR 1926.451(a)(2)-The interpretation stated that the "concrete
block is not always an 'unstable object' when used as a base for scaffolding. The circumstances
and techniques under which it is used must be considered to determine its stability." In the
revised standard, the provision barring the use of unstable objects to support scaffolds has
been moved to §1926.451(c)(2)(ii). Although the revised provision no longer provides
specific examples of unstable objects, this interpretation from 1978 remains true under the
revised standard. However, hollow-core masonry units would never be acceptable to support
- Regarding the superseded bracing requirements (please note, the 1978 reference to 29 CFR
1926.451(a)(3) is incorrect, but bracing is required by several other provisions) -- The
interpretation stated that "A brace is defined in 29 CFR 1926.452(b)(3) as a tie that holds one
scaffold member in a fixed position with respect to another member. The fact that a scaffold
member has a place for a brace does not necessarily require that the brace be in place, if it
interferes with the erection or stocking of the scaffold. This is only true if the scaffolding
is capable of supporting four times the maximum intended load and meets the other applicable
requirements of 29 CFR 1926.451. Also, the manufacturer's design specifications, particularly
with respect to the lateral stresses involved, are an important aspect that must be considered
in the decision to remove pieces of bracing."
In the revised standard, the definition of the term "brace" has been changed editorially by
replacing the word "tie" with "rigid connection," but the above interpretation is still true
provided that a competent person approves the scaffold design. In the revised standard, the
provision that scaffolds shall be capable of supporting four times the maximum intended load has
been moved to §1926.451(a)(1).
- Regarding superseded 29 CFR 1926.451(a)(7) and (8) -- The interpretation stated that "A
scaffold plank is considered a component of the scaffolding. As such, it must be capable of
supporting four times the maximum intended load without failure (a safety factor of four.) The
fact that a plank might have a split in one end does not automatically mean that it must be
removed from service, provided it does not otherwise create a hazard to the employees."
As noted above in our answer to b., the revised standard redesignated the provision that
scaffolds shall be capable of supporting four times the maximum intended load to
§1926.451(a)(1). The provision that damaged or weakened scaffold components shall be
immediately replaced or repaired was amended in the revised standard, and redesignated to
§1926.451(f)(4). Revised paragraph (f)(4) addresses scaffold use and references back to
the scaffold strength requirements in paragraph (a)(1). The interpretation above from 1978 is
still valid under the revised standard with the approval of a competent person.
- Regarding superseded 29 CFR 1926.451(d)(4) -- The interpretation stated that scaffold legs
are required "to be placed on a foundation that is adequate to support four times the intended
load of the scaffold. The standard does not require that base plates always be employed, but
only when conditions necessitate their use. For example, the scaffold legs cannot be placed on a
mud foundation without a base to prevent the legs from sinking into the mud."
In the introductory text to §1926.451(c)(2), the revised standard requires base plates
(and mud sills or other adequate firm foundation) at all times now for support scaffold poles,
legs, posts, frames, and uprights.
Should you require further assistance, please do not hesitate to contact us again by writing to:
OSHA Directorate of Construction, Office of Construction Standards and Compliance Assistance,
Room N3621, Washington D.C., 20210.
Roy Gurnham, Director
Office of Construction Standards and Compliance Assistance