Solution Summary: Installing Permanent Tie-in Anchor Systems During the Design Phase
Installing permanent tie-in anchor systems is a prevention through design (PtD) process that addresses worker exposure to potential fall hazards from scaffold collapses during the construction, repair or maintenance of buildings. The system consists of a metal bracket anchor that is permanently attached to the inner structural core of the building and a welded turned eye-bolt that goes through the building's non-structural external layer and cavity to thread into the bracket, providing the building tie. Installing permanent tie-in anchor systems is stronger than relying on the strength of day old veneer in which the eye-bolt is embedded.
Permanent tie-in anchor systems, such as Non-Stop Scaffolding Inc.'s wall tie-in anchor system, provides a metal anchor bracket that can be drilled to the concrete slab of the inner core or metal framing of the structure and may be rotated to adjust the placement of the eye-bolt in the head joint or bed joint of the veneer. Their 3/8 turned eye-bolts are welded shut to achieve industry-rated strength.
Eye-bolt resting on bed joint
Eye-bolt resting on head joint
The anchor brackets and eye-bolts come in different sizes to accomodate the different cavity sizes and veneer thickness.
- 1" to 4" cavity
- 4" to 8" cavity
- 3/8 x 4-inch
- 3/8 x 6-inch
- 3/8 x 8-inch
- 3/8 x 10-inch
Working on scaffolds at a height that is more than four times its minimum base, as a general rule, becomes inherently unstable even if it is plumb and square. Falls from height typically result in severe injuries or death. Installing permanent tie-in anchor systems anchorages the scaffold to prevent it from tipping and is stronger than relying on the strength of day old veneer to secure the tie-in.
How Risks are Reduced:
Building ties connect the scaffold to the structure which provide support and stability to resist wind and other lateral loads.
OSHA regulation requires using guys, ties and braces when working on scaffold at a height that is more than four times its minimum base dimension to prevent tipping. OSHA also requires ties, guys, braces, or outriggers to prevent tipping of supported scaffolds where an eccentric loads, such as a cantilevered work platforms, is applied.
Effects on Productivity:
Wall tie-in anchor systems can increase productivity.
When it is not feasible to install building ties, consider sufficient room in the design to accomodate outriggers or buttresses to secure the scaffold
Permanent, reusable tie-in anchor systems provide convenience and a life cycle benefit for future building maintenance when scaffolding is needed
Scaffolds and scaffold components must be inspected for visible defects before each shift by a competent person, and after each occurence that could affect a scaffold's integrity [OSHA regulation 1926.451(f)(3)]
Guys, ties, and braces must be installed at locations where horizontal scaffold components support both inner and outer legs [OSHA regulation 1926.451(c)(1)(i)]
- If the scaffold base is 3 feet or less, the first tie will be a vertical distance of four times the base width and every 20 feet vertical thereafter. If the scaffold base is wider than 3 feet, the first tie will be a vertical distance of four times the base width and every 26 feet vertical thereafter [OSHA regulation 1926.451(c)(1)(ii)]
Le, Jean Christophe, MPH - CPWR The Center for Construction Research and Training
NIOSH Workplace Solutions Sheet
The National Institute of Safety and Health (NIOSH) has published a series of “Workplace Solutions”, which are easy-to-understand recommendations from NIOSH research results. Related to this Construction Solution, please find more information on: Preventing Falls from Heights through the Design of Embedded Safety Features and Supporting Prevention through Design (PtD) Using Business Value Concepts