United States
Hong KongMasonry bracing and limited access zones
A limited access zone is required on the unscaffolded side of a masonry wall over 8 feet, equal to the wall height plus 4 feet. Bracing stays until permanent supporting elements are in place.
A wall that will be perfectly stable when the building is finished can fall over while it is being built. Subpart Q addresses that directly.
The limited access zone
Required before construction begins on any masonry wall over 8 feet, on the side that will be unscaffolded, at 29 CFR 1926.706(a).
It runs the entire length of the wall and extends a distance equal to the wall height plus 4 feet.
Only employees actively engaged in constructing the wall may enter it.
A 12 foot wall needs a zone extending 16 feet. Questions give you a height and ask for the distance, and the plus four is what candidates forget.
Bracing
A masonry wall over 8 feet must be adequately braced to prevent overturning and collapse, and the bracing stays until permanent supporting elements are in place, at 1926.706(b).
Permanent supporting elements means the floor or roof structure that will ultimately hold it, not a temporary prop somebody thinks is enough.
Why walls fall
Wind, mostly. A freshly built wall has green mortar with little tensile strength and no lateral support, and a gust catches a large flat surface.
That is why the zone is on the unscaffolded side: the scaffold side has people and structure, and the other side is where it falls.
This lives in OSHA
It is a masonry category question whose answer is in the safety standards rather than a masonry text. If you are searching a masonry reference for it, you are in the wrong book.
Common questions
When is a limited access zone required?
Before construction begins on a masonry wall over 8 feet, on the unscaffolded side.
How far does the zone extend?
The wall height plus 4 feet, running the entire length of the wall.
Who may enter it?
Only employees actively engaged in constructing the wall.
How long does bracing stay?
Until permanent supporting elements are in place.
Which book answers this?
The OSHA standards, at 29 CFR 1926.706, rather than a masonry reference.