United States
Hong KongFormwork and shoring
Formwork and shoring may only be removed when the concrete has gained sufficient strength, determined under a plan prepared by a qualified person, at 29 CFR 1926.703(e).
Formwork holds wet concrete in shape and carries its weight until it can carry itself. The dangerous moment is deciding when that is.
The removal rule
Formwork and shoring may not be removed until the employer determines the concrete has gained sufficient strength to support its weight and superimposed loads.
That determination is based on a plan prepared by a qualified person, at 29 CFR 1926.703(e).
This one needs technical expertise rather than authority to stop work. It is a structural determination and the standard says so specifically. Questions offer competent person as the distractor.
Reshoring
Shoring placed back under a slab after the original shoring is removed, to carry load from levels above while the concrete continues gaining strength.
A multi-story pour transfers load downward through several levels, which is why reshoring exists and why removing it out of sequence is dangerous.
Design and inspection
Formwork is designed, fabricated, erected, supported, braced and maintained so it supports all vertical and lateral loads that may be applied.
Drawings or plans for the jack layout, shoring and working decks are available at the jobsite.
Vertical slip forms and lift-slab
Both have their own provisions in Subpart Q, and lift-slab operations in particular are tightly controlled after a well-known collapse.
Rebar impalement
Protruding reinforcing steel must be guarded to eliminate the hazard of impalement, at 29 CFR 1926.701(b). Simple, absolute, and asked.
Common questions
When may formwork be removed?
When the concrete has gained sufficient strength, determined under a plan prepared by a qualified person.
Is that a competent or qualified person?
Qualified. It is a structural determination requiring expertise rather than authority.
What is reshoring?
Shoring placed back under a slab after the original is removed, to carry load from levels above while strength develops.
Where are formwork drawings kept?
At the jobsite, covering jack layout, shoring and working decks.
What is required for protruding rebar?
Guarding to eliminate the impalement hazard, at 29 CFR 1926.701(b).