Solution Summary: Considering Roof Parapets During the Design Phase
The proper design of roof parapets at a specific height and test load is a prevention through design (PtD) process that addresses worker exposure to fall hazards during the design stages of a project. Roof parapets are the parts of the wall assembly that extend above the roof and can prevent falls from flat low-sloped roofs. Having roof parapets installed could minimize, or even eliminate, the need for additional fall arrest roof anchors (and related personal fall arrest equipment), temporary barricades, or signs during operation and maintenance tasks.
Parapet walls may also qualify as guardrails. OSHA requires, under 29 CFR 1926.502(b)(1), that the top rail be at least 39 inches tall and capable of withstanding, without failure, a force of at least 200 pounds applied within 2 inches of the top edge, in any outward or downward direction, at any point along the top edge.
Diagram by Nicholas Tymvios and John Gambatese, Oregon State University; not shown in the diagram is the strength requirement needed to withstand 200 pounds of force.
Alternatively, temporary guardrail systems can supplement the parapet to achieve a minimum 39" guardrail height for fall protection.
RaptorClamp™ by the manufacturer AES RAPTOR
Working from heights such as near unprotected roof edges can expose workers to potential fall hazards when no passive fall protection is in place. Falls from height typically result in severe injuries or death. Designing parapet walls onto buildings creates a passive fall protection system that does not require special fall prevention equipment or active participation from workers to eliminate the risk.
How Risks are Reduced:
A parapet that meets the height and strength requirement for fall prevention provides passive fall protection with no action required on the part of the worker.
For more information on risk reduction, please refer to NIOSH Workplace Design Solutions Publication# 2014-108 (see right column).
Effects on Productivity:
There is anecdotal evidence that workers may be more focused and productive when they have the perception that the risk of falling has been reduced or eliminated.
Since workers need to access the roof during construction of a building, they can be exposed to fall hazards before parapets can be completed. During this time, the following interim measures may be required to protect workers from falls:
- Guardrails that meet OSHA height and strength requirements
- Anchor points with appropriate personal fall arrest systems and lifelines
- Other forms of fall protection, such as safety netting
Ensure that parapets meet any additional structural requirements when they are used as anchorage for personal fall arrest systems or as support for scaffolds.
Parapets need to have the same fire rating as the wall below.
To protect the integrity of a masonry parapet from weather elements, a capstone should be installed on top of the parapet to prevent water from seeping in and generating cracks.
Evaluate the roof load with the parapet walls to determine if roof structure modifications may be necessary.
Le, Jean Christophe, MPH - CPWR - The Center for Construction for Research and Training
- Construct parapet walls and guardrails
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 and Preventing Falls through the Design of Roof Parapets
Guardian Fall Protection Parapet Clamp Guardrail
To obtain information, visit Parapet Clamp Guardrail or contact 1-800-466-6385
Qualcraft Industries Parapet Anchor System
To obtain information, visit Parapet Anchor System or contact 1-800-231-5647
Norguard Parapet Clamp Guardrail System
To obtain information, visit Parapet Clamp Guardrail System or contact 1-800-267-6855
Fall Protection Equipment
Fall protection equipment for residential construction classified by the type of equipment and the phase of construction can be found on this Washington University website. http://www.ot.wustl.edu/fptech/homepage.htm