Bristolite Advantage
Our mission at Bristolite is to provide our customers with the highest quality products and supreme service at an exceptional value. We also aim to provide the industry with an abundance of accurate and useful information relative to daylighting and energy conservation. We take our corporate responsibility to our employees, associates, industry colleagues and customers very seriously and we see ourselves as stewards for the efficient use of sustainable carbon free energy.

OSHA Fall Protection

The Federal OSHA Walking-Working Surfaces, Guarding Floor and Wall Openings and Holes, Construction Fall Regulations applicable to skylights.

CFR# 1910.21(a)(1)

"Floor hole." An opening measuring less than 12 inches but more than 1 inch in its least dimension, in any floor, platform, pavement, or yard, through which materials but not persons may fall; such as a belt hole, pipe opening, or slot opening.

CFR# 1910.23(a)(4)

Every skylight floor opening and hole shall be guarded by a standard skylight screen or a fixed standard railing on all exposed sides.

CFR# 1910.23(e)(8)

“Skylight screens shall be of such construction and mounting that they are capable of withstanding a load of at least 200 pounds applied perpendicularly at any one area on the screen. They shall also be of such construction and mounting that under ordinary loads or impacts, they will not deflect downward sufficiently to break the glass below them. The construction shall be of grillwork with openings not more than 4 inches long or of slatwork with openings not more than 2 inches wide with length unrestricted.”

If after reading the above OSHA CFRs one questions their applicability to skylights see the following. If you click on the 1910.23(e)(8)link you will be taken to the OSHA web site and shown the following letter. We believe since the letter is posted on the OSHA web site exactly as presented here and because it’s a matter of public record we are justified in sharing the letter in this document.

Fall protection is a major issue in our industry; and rightfully so. OSHA, industry authorities such as AAMA and ICC, standards and testing institutions such as NFRC and ASTM, skylights manufacturers, building managers and owners, architects, roof consultants, contractors, companies providing building services that require their employees to work on a roof and any person who earns their living working on a roof whether full time or only occasionally need to work together to address this life safety issue.

We recommend that those parties responsible for building roof access train those people permitted access to the roof in fall protection and inform them of all of skylight locations. In cold climates it is not unusual for skylights to be covered with snow.

The federal OSHA CFRs related to skylights have created a serious problem that must be addressed. The regulations are ambiguous and do not address the dynamic force generated when a person falls on a skylight.

Let’s break down the regulation.

“capable of withstanding a load of at least 200 pounds”

Load” is a static weight or mass that is supported. Load is the wrong measure for a fall protection regulation. When a person falls on a skylight they place a dynamic impact force on the skylight. The regulation should use impact force. A force that transitions from a kinetic energy of some value to an abrupt zero energy is an impact force (IF). Impact force is calculated as Impact Force = (2 x Mass x Velocity) / Time (duration time of impact) or IF = (2 x m x v) / t.

“applied perpendicularly at any one area on the screen.”

Any one area” could literally mean one square inch or thirty square feet; or any area in between on a 5’ by 6’ skylight. Using the 200 lb load in the regulation and the unspecified load area a 5’ x 6’ skylight that is capable of supporting a static load of 6.67 lb per square foot complies with the regulation. The regulation should specify a quantified load area.

In summary, to be effective the regulation should specify an impact force on a quantified impact area. Impact force on an area is then expressed as pressure per square (unit of measure).

Because the current OSHA regulation is ambiguous and meaningless, fall protection has become more a matter of marketing rather than one of regulation and conformance. In the absence of an effective national skylight fall protection regulation or standard whether from OSHA or some other regulatory or standards institution some manufacturers are devising their own fall protection standards and testing methods and promoting their ideas to skylight specifiers and buyers. Following are two such specifications that we see with some frequency.

Specification A:
Drop Test: The 200 lb (91kg) drop test from a height of 24” (610mm) above the center (highest point) of the dome shape and at mid points of both the 5 foot (1,524mm) and 6 foot 1,829mm) said approximately 15 inches (381mm) and 18 inches (457mm) from center. The 200 lb load must be contained within a flexible bladder or sack having approximate dimensions no larger than 30 inches long, 20 inches wide, and 8 inches high (762mm x 508mm x 203mm), filled with course sand or pea gravel. The dome must withstand the sack drop without inverting or breaking.

Specification B:
Fall protection: No breakage or disengagement of dome from the frame shall occur upon impact of up to
1,000 foot lb

Let’s calculate the impact force of these two “marketing” fall protection specifications.

  Drop weight   Drop height   Acceleration due to gravity
- velocity
Duration time of impact Impact force
- newton meters
Convert newton meters (.737) to foot lb

Impact area

Force per unit area is pressure
  lb kgs inches meters √ 2gh t (2xmxv)/t foot lb sq inches lb per
sq inch
200 lb bag measuring 30" x 20" dropped from a height of 24"
A 200 90.9 24.0 0.610 3.46 0.3 1,888.3 1,391.7 600.00 2.3
1,000 foot pounds. No impact area or drop height specified, so calculated for weight using same impact area and drop height as spec A to achieve 1,000 ft lb force
B 144 65.5 24.0 0.610 3.46 0.3 1,359.6 1,002.0 600.00 1.7
267 lb bag with a 5.5" diameter bull nose dropped from a height of 36"
ASTM 267 121.4 36.1 0.917 4.24 0.3 3,091.7 2,278.6 23.75 95.9

 

We are not impressed with the impact force/pressure of specification A (2.3 lb per sq inch) or B (1.7 lb per sq inch).

However, we are impressed with the third specification included in the calculations. This calculation is based on testing parameters in the current draft of a new potential ASTM skylight fall protection standard. The ASTM committee working on this standard started their work by developing an understanding as to how a worker most normally falls on a skylight and the dimensions and dynamics of the human body. The draft standard requires dropping a 267 lb sand filled canvas bag with a 5.5” diameter bull nose from 36.1 inches (less the height of the skylight curb) on the skylight glazing. The calculated impact force/pressure as shown in the above table is 95.9 lb per sq inch. We hope this standard or a similar standard will soon be finalized and adopted by OSHA so that this important life safety issue can be adequately addressed.

In the meantime, skylight specifiers and buyers should rebuke the “marketing” fall protections standards promoted by various skylight manufacturers and become knowledgeable about the relative strength and impact resistance of the glazing materials available in the industry. At Bristolite our strongest and highest impact resistant glazings include Energy Star Fiberlite, Tufflite Polycarbonate and Trituff Copolyester.

Most skylight manufacturers do load testing on the glazings and fastening systems they utilize in the construction of their skylights, but we are not aware of much load testing on weathered glazings after 10, 15 or 20 years of service. All plastics age over time with exposure to the elements of sun, rain, wind and pollution. As the plastic ages its strength and impact resistance decline. Therefore, to obtain maximum safety for the entire service life of a skylight we recommend the installation of safety screens or security grills under the skylights.

ICC acceptance criteria for plastic unit skylights contains the following requirement.

All Bristolite skylights (regardless of glazing material and load test performance) are labeled with the following fall protection warning.

WARNING

" This skylight is designed to withstand normal elements of weather. It has been designed to meet the structural weight loading requirements of 29 CFR 1910.23(e)(8). It has not been designed and is not intended to be utilized as a walking or working surface. It is not designed to withstand human impact or falling objects. The owner or designer should restrict access to the proximity of the skylight to authorized personnel who have been fully informed regarding the potential fall hazards of the skylight as well as the location of the skylight and that contact with the skylight by authorized personnel, tools or other objects must be avoided."

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