DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Preventing Falls through the 

Design of Roof Parapets

Summary

Workers are exposed to risks from 

falls during construction, operation, 

maintenance, and demolition of buildings. Parapets are the parts of the wall 

assembly that extend above the roof 

[Rajendran and Gambatese 2013] and 

can prevent falls from low-sloped (flat) 

roofs. Other design features that can 

prevent falls include using guardrail systems and permanent anchor points (for 

use with personal fall arrest systems and 

lifelines) [See NIOSH 2013 for more 

information].

Description of 

Exposure

Construction is one of the most dangerous industries [Toole and Gambatese 

2008], and falls are a frequent cause of 

fatal and nonfatal injuries. Of the 4,609 

fatal work injuries that occurred in 

2011, 541 (12%) were the result of falls 

to a lower level [BLS 2012]. Worker’s 

compensation providers estimate that 

each fall from elevation (fatal or nonfatal) in construction costs between 

$50,000 and $106,000 [OSHA 2012].

Workers may be close to roof edges and 

exposed to fall hazards when accessing 

building roofs during construction and 

for operation and maintenance tasks 

after the building has been completed. 

Workers may be close to roof edges 

when transferring material to and from 

the roof, accessing rooftop equipment, 

and communicating with coworkers on 

the ground. To prevent falls, parapets 

can be built on the roof edges during 

building construction. The need for 

additional fall arrest roof anchors (and 

related personal fall arrest equipment), 

temporary barricades, or signs during 

operation and maintenance tasks would 

thus be minimized or even eliminated if 

parapets are more than 39 inches tall [29 

CFR* 1926.502(b)(1)]. 

The NIOSH Fatality Assessment and 

Control Evaluation (FACE) program (an 

activity of the NIOSH Division of Safety 

Research (DSR) investigates worker 

fatalities to determine causes, and recommends injury prevention measures. 

Behm [2005] analyzed 224 FACE case 

reports and found that 42% of fatalities 

might be linked to the building design, 

and 6 fatalities may have been prevented 

if the building designs had included 

parapets for fall protection.

*Code of Federal Regulations. See CFR 

in References.

Contents

▶ Summary

▶ Description of Exposure

▶ Case Study

▶ Design Solutions

▶ Standards

▶ Cost Savings/Advantages

▶ Recommendations

▶ Acknowledgments

▶ References

Prevention through 

Design (PtD)

PtD addresses worker exposure to 

hazards during the design stages of 

a project. When a building is designed, risks of fall-related injuries 

and fatalities can be minimized 

with a life-cycle approach to address 

fall hazards for the workers who 

construct, operate, maintain, and 

eventually demolish a building. This 

approach can include using a building’s features to address fall hazards 

in construction plans, considering 

safety when buying equipment, 

and communicating risks to building owners and facilities personnel 

[Behm 2005]. 
Case Study

A 32-year-old project engineer was fatally 

injured when he fell from a roof. Three 

engineers were examining a building and 

measuring the roof for an insulation cost 

estimate. The roof was completely flat all the 

way to the edges and did not have a parapet. 

Two of the engineers were measuring the 

roof with a tape measure. The third was 

writing down the measurements. As they 

were about to leave, they noticed that they 

had not measured one section of the roof. 

While two engineers and the maintenance 

person waited by the door, the victim, carrying a flashlight, pulled out the tape measure while quickly walking backward from 

the door. He walked over the edge and fell. 

The distance from the penthouse door to 

the edge of the roof was approximately 38 

feet. The victim fell approximately 29 feet to 

the sidewalk below. Emergency medical services were called and arrived on the scene. 

The victim was transported to a nearby local hospital where he was pronounced dead 

on arrival [NIOSH 1997].

Although a fall protection system is not be 

required by law (29 CFR 1926.500) when performing site evaluations for bids, controls for 

fall hazards are still necessary, such as a safety 

monitoring system [NIOSH 1997]. Parapets 

would have ensured that fall protection was 

already designed into the building. In the 

above case, the parapet was not required by 

law but might have saved the worker.

Design Solutions

The decision to add parapets or to extend 

the height of a planned parapet is made 

during the conceptual design of a building. 

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 needed to 

protect workers from falls:

▶ Job-built or commercially available guardrails that meet OSHA height and strength 

requirements [Bobick et al. 2010] 

▶ Properly designed anchor points with 

appropriate personal fall arrest systems 

and lifelines

▶ Other forms of fall protection, such as 

safety netting

In addition, some parapet designs require 

that building columns extend above the 

roofline of the building, so the parapets 

can tie into the columns. While these parapets are being constructed, the extended 

columns can provide temporary lifeline 

anchor points. Such columns also provide a 

visual reference point for the roofing crew, 

which has been suggested as an important 

component for maintaining balance [Hsaio 

and Simeonov 2001]. After parapets are 

finished, they can serve as fall protection for 

the remainder of the building construction.

Eliminating hazards is the first priority in 

the hierarchy of controls, and takes precedence over the use of personal protective 

equipment [Gambatese et al. 2005]. Elimination of a hazard is best accomplished in 

the concept and design phase of a project 

[ANSI/ASSE 2011]. Once complete, parapets eliminate the fall hazard. They are 

considered to be a passive fall protection 

system, meaning workers are protected 

without the need for additional action. Passive systems are preferred over active systems that depend on specific action by the 

worker [NISOH 2000].

Standards

OSHA construction regulations require 

guardrails for elevated work (6 feet or 

more above the ground) to be a height 

of 42 inches (1.1 m) plus or minus 3 

inches (8 cm) [29 CFR 1926.502(b)

(1) www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=10758&p_

table=STANDARDS].

Roof designs that included 42-inch high 

parapets would meet the minimum OSHA 

requirements for guardrail fall protection 

[Gambatese et al. 1997] (See Figure 1).

Cost Savings/

Advantages

Since Federal OSHA regulations state 

that employee safety is the responsibility of the employer, hazards are not 

always considered by architects or design 

engineers during the design phase of a 

construction project. Issues might include 

the cost and time to construct the parapet; designs are meant to be completed on 

schedule and cost effective for the owner 

[Gambatese et al. 1997; Gambatese et al. 

2005; Toole and Gambatese 2008]. With a 

large roof, the increased cost that comes 

with guarding the perimeter may be significant [Rajendran and Gambatese 2013]. 

But these increased costs of safe design 

(for labor, materials, including parapets 

etc) can be offset by long term savings over 

the life cycle of the building that begin to 

accrue soon after construction of the parapet. When parapets are designed in and 

fall hazards reduced through design, temporary guardrails and other types of fall 

protection may not be needed during most 

roof maintenance operations [Gambatese 

et al. 1997]. 

The use of parapets can save costs in additional ways. It is recommended that 

equipment, vents, access points, etc., be 

placed 15 feet back from the roof edge to 

reduce the risk of falling during servicing 

and maintenance. This would no longer be 

necessary with parapets. More of the roof 

can be used, making work more efficient 

[OSHA Alliance Program 2010; Rajendran 

and Gambatese 2013]. If properly designed 

(39-inch or taller) parapets are in place, 

fall restraint systems would no longer be 

needed for maintenance work within the 

perimeter of the parapet. However, fall 

protection would still be required for work 

on roof-top equipment/design features at 

heights greater than 6 feet, over the edge of 

the parapet, on the face of the building, and 

for work near unguarded roof openings 

and skylights. 

Including parapets of sufficient height is 

also advantageous when green features 

such as vegetated roofs or rooftop photovoltaic solar panels are being considered, 

as these features do involve regular maintenance activities. Additional advantages 

include the following [Pupkin 2013]: (1) 

Parapets reduce wind flow over the roof so 

that wind uplift resistance is evenly distributed. (2) Parapets can help prevent rainwater damage on the exterior of buildings. 
Roof

Parapet

min 39”

(3) Parapets can hide roofing material or 

equipment that is unsightly or unattractive.

Recommendations

Designers should take the following steps 

to prevent falls from roofs during construction [Gambatese et al. 1997, 2005; OSHA 

Alliance Program 2010; ICC 2012]:

▶ Ensure that parapets meet the OSHA 

height requirement for guardrails of 42 

inches (1.1 meters) plus or minus 3 inches (8cm) above the finished roof surface. 

An additional 6 inches may be necessary 

to account for subfloor depth, beams, 

columns, etc.

▶ Ensure that the parapet can withstand a 

force of at least 200 lbs (applied within 

2 inches of the top edge in any outward or downward direction) [29 CFR 

1926.502(b)(3) and (4)].

▶ Install a capstone over masonry parapet 

walls to prevent water from getting in 

and causing cracks. 

▶ Consider the design of drainage systems, 

roof access, and insulation to accommodate parapets. 

▶ Consider other uses for parapets during 

the design stage, such as anchorage for 

personal fall arrest systems and support 

for window-washing scaffolds (taking into account additional structural 

requirements that may be imposed by 

these other uses).

▶ Ensure that the parapet has the same fire 

rating as the wall below.

▶ Carefully evaluate additional snow loading and roof ponding loads when considering a parapet wall. The additional roof 

loading may require extensive modifications or re-design to the roof structure. 

Consult local building codes.

Acknowledgments 

This document was prepared by Susan 

Afanuh and Pamela Heckel of the NIOSH 

Education and Information Division (EID), 

and is based on research conducted by 

NIOSH partners. Tom Bobick, Paul Moore, 

and Virgil Casini of the Division of Safety 

Research; and Donna Heidel (formerly 

with NIOSH) and Mike Barsan of EID provided valuable input through their review 

comments.

References

ANSI/ASSE [2011]. Prevention through 

Design guidelines for addressing occupational hazards and risks in design and 

redesign processes. Standard Z590.3.

Behm M [2005]. Linking construction 

fatalities to the design for construction 

safety concept. Safety Sci 43:589−611. 

http://www.sciencedirect.com/science/

article/pii/S0925753505000731

BLS [2012]. Census of Fatal Occupational 

Injuries Summary, 2011. Washington, 

DC: Bureau of Labor Statistics. http://

www.bls.gov/news.release/cfoi.nr0.htm

Bobick TG, McKenzie, Jr, EA, Kau T-Y 

[2010]. Evaluation of guardrail systems 

for preventing falls through roof and 

floor holes. J Safety Res 41:203‒211.

Figure 1. Design of a building using a parapet. (Diagram by Nicholas Tymvios and John Gambatese, Oregon State University)
CFR. Code of Federal regulations. Washington, DC: U.S. Government Printing 

Office, Office of the Federal Register. 

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=10758&p_

table=STANDARDS

Gambatese JA, Hinze JW, Haas CT [1997]. 

Tool to design for construction worker 

safety. J Arch Eng March:32−41.

Gambatese JA, Behm M, Hinze JW [2005]. 

Viability of designing for construction 

worker safety. J Constr Eng Manage September:1029−1036. http://faculty.kfupm.

edu.sa/cem/jannadi/Viability-of-Designing-for-Construction-Worker-Safety.pdf

Hsaio H, Simeonov P [2001]. Preventing 

falls from roofs: a critical review. Ergonomics 44(5):537‒561.

ICC [2012]. International Building Code. International Code Council, Standard 714.1.

NIOSH [1997]. Project engineer dies in fall 

from roof in Massachusetts. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for 

Occupational Safety and Health, MA FACE 

97−MA−044−01. http://www.cdc.gov/

niosh/face/stateface/ma/97ma044.html

NIOSH [2000]. Worker deaths by falls: a 

summary of surveillance findings and 

investigative case reports. By Braddee 

RW, Hause MG, Pratt S. Cincinnati, OH: 

U.S. Department of Health and Human 

Services, Centers for Disease Control 

and Prevention, National Institute for 

Occupational Safety and Health, DHHS 

(NIOSH) Publication No. 2000‒116. 

http://www.cdc.gov/niosh/docs/2000-

116/pdfs/2000-116.pdf

NIOSH [2013]. Architectural design and 

construction: instructor’s manual. Cincinnati, OH: U.S. Department of Health 

and Human Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and 

Health, DHHS (NIOSH) Publication No. 

2013‒133. http://www.cdc.gov/niosh/

docs/2013-133/. 

OSHA [2012]. Workers’ compensation costs 

of falls in construction. Washington, DC: 

U.S. Department of Labor, Occupational 

Safety and Health Administration. http://

www.osha.gov/dcsp/products/topics/

businesscase/costs.html

OSHA Alliance Program [2010]. Construction workplace design solutions: specify 

sufficient wall height to allow parapets to 

function as fall prevention. OSHA Alliance Program Construction Roundtable 

http://www.designforconstructionsafety.

org/Documents/Parapets_rev9.doc

Pupkin A [2013]. Parapet roofs. Ezine 

Articles. August 15. http://ezinearticles.

com/?Parapet-Roofs&id=7937534

Rajendran S, Gambatese JA [2013]. Risk 

and financial impacts of prevention 

through design solutions. Pract Period 

Struct Des Constr 18(1):67–72. 

Toole TM, Gambatese J [2008]. The trajectories of Prevention through Design in construction. J Safety Research 

39:225−230. http://www.cdc.gov/niosh/

topics/ptd/pdfs/Toole.pdf

For More Information 

The information in this document is based on research related to Prevention through Design (PtD) initiatives. More 

information about PtD is available on the NIOSH Web site at 

http://www.cdc.gov/niosh/topics/PtD/ 

More information about the NIOSH FACE Program can be 

found on the NIOSH Web site. 

▶ http://www.cdc.gov/niosh/face/

▶ Click here for a list of NIOSH FACE Reports related to 

construction falls.

▶ Click here for a list of State FACE Reports related to construction falls. 

To obtain information about other occupational safety and 

health topics, contact NIOSH at:

Telephone: 1–800–CDC–INFO (1–800–232–4636)

TTY: 1–888–232–6348 • CDC INFO: www.cdc.gov/info

or visit the NIOSH Web site at www.cdc.gov/niosh

For a monthly update on news at NIOSH, subscribe to 

NIOSH eNews by visiting www.cdc.gov/niosh/eNews. 

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Furthermore, NIOSH is not responsible for the content of 

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This document is in the public domain and may be 

freely copied or reprinted. NIOSH encourages all readers of the Workplace Design Solutions to make them 

available to all interested employers and workers.

As part of the Centers for Disease Control and Prevention, 

NIOSH is the Federal agency responsible for conducting 

research and making recommendations to prevent workrelated illness and injuries.

December 2013 Publication No. 2014–108

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