Roof Edge Protection
There are many standards relating to both temporary and permanent roof edge protection around the globe. These standards include:
- Workplace Health Safety & Welfare Regulations 1992
- BS 6180 Protective Barriers In and About Buildings 1999
- The Building Regulations Part K 2013
- HSE Specialist Inspectors Report No 15 1987
- BS 6399 Part 1 Loading for Building 1996
- BS 6399 Part 2 Code of Practice for Wind Loading 1997
- Construction Health, Safety and Welfare Regulations 1996
- HSE Health & Safety in Roofwork 2012
- EN 13374 Temporary Edge Protection Systems – Product Specification, Test Methods 2013.
- EN 14122-3 Safety of machinery. Permanent means of access to machinery, stairways, stepladders and guardrails 2010
- The Work at Height Regulations 2005
- OSHA Reg 29 CFR 1910.23 (E) (1); (E) (3) (IV).
- OSHA Reg 29 CFR 1926.502 (B) (1) – (B) (14).
- OSHA Reg 29 CFR 1926.501 (b) (1); (b) (2) (ii)
- Canadian National Building Code 22.214.171.124(1)(e), 126.96.36.199(2), 188.8.131.52(4)
- Ontario Building Code Section 184.108.40.206(1)(b), 220.127.116.11(2), 18.104.22.168(4)
The above standards often cause confusion when individuals are trying to specify a guardrail product as many require different load and testing criteria. In addition, there are no specific standards that deal with cantilevered guardrails which are used as both temporary and permanent product solutions, hence further confusion.
The UK Building Regulations Part K requires a guardrail to consist of a minimum two horizontal rails with a minimum height of 1100mm. The loading criteria is taken from BS 6399 part 1 1996 and requires the guardrail to withstand a uniformly distributed load of 0.74kN per metre and a point load of 0.5kN.
Part K2 has a specific heading “Guarding of areas used for maintenance” Clause 3.4b states “If access will be required less frequently than once a month: it may be appropriate to use temporary guarding…” “The Construction (Design and Management) Regulations 2007 (CDM) and the Work at Height Regulations 2005 give provisions for such measures.”
Hence this is a relaxation of the suggested loadings contained within Part K where the frequency of access is low and controlled.
The referral to the CDM Regulations 2007 requires a risk assessment to be made to ensure that the guardrail is suitable and sufficient to prevent both persons and objects from falling.
In Europe EN 13374 provides for the design of temporary edge protection systems and requires a system to withstand loads applied perpendicular, horizontal and vertical to the system. This standard was initial introduced in 1997 and replaced the UK HSE Specialist Inspectors Report No 15 1987 and other European Standards. EN 13374 has recently been revised by Technical Committee 53, Working Group 10 (TC53/WG10). During the Working group meetings there was discussion of changing the title of this European Norm to accommodate permanent counter balanced systems. Unfortunately the change never occurred, however, in the UK National Forward there is clear reference to include such permanent counter balanced systems.
“This standard can also be applied where the protection of only a few persons, in a controlled environment, not subject to panic, crowd control or access by the general public, can be demonstrated (e.g maintenance of plant and equipment on roofs”).
The European Norm establishes three classes of edge protection system.
- Class A - 0-10 degree roof pitch
- Class B - 10-30 degree roof pitch
- Class C - 30-45 degree roof pitch
All classes have a static load requirement and class B & C also have a dynamic load applied representing someone rolling down the roof slope and making contact with the edge protection system.
Under Clause 7.3 friction or counterbalanced systems should be tested at the maximum inclination, according to the manufacturers Operation & Maintenance manual. The performance will vary according to the roof pitch, base material (wet or dry) and whether or not there is an upstand (restraint/edge) present. The manufacturer needs to demonstrate compliance to this standard through testing the permutations they claim are suitable for their product to be installed on.
Due to the above confusion and uncertainty, companies have commissioned independent assessment and testing by institutions, such as, ”The British Board of Agrément.” In situations, where there are no specific standards relating to a product, it is essential to establish the product is “fit for the intended use.”
In the absence of an appropriate standard some European authorities have applied inappropriate standards such as EN 14122-3 Safety of machinery. Permanent means of access to machinery, stairways, stepladders and guardrails 2010. This standard provides a UDL and a deflection criteria. However it fails to mention roof pitch, roof membrane, wet or dry conditions, upstand details or toe-board requirement. Clearly this standard is intended for guardrails around plant and machinery, nevertheless it is often specified inappropriately and the French version adds a dynamic load in accordance with NF E85-003.
Wind Loading Criteria
In addition to these requirements the edge protection system, when installed permanently, should also comply with appropriate wind loading criteria. In the UK this is BS 6399 Part 2 Code of Practice for Wind Loading.
In Europe and USA the wind loading standards are:
- Eurocode 1: Actions on structures - Part 1-4: General actions - Wind loads.
- ASCE7 - The American Society of Civil Engineers design standard: “Minimum Design Loads for Buildings and Other Structures.
Although EN 13374 now includes a degree of wind loading assessment it has become clear that wind loading is a far more onerous force than that of a person falling against a guardrail. Therefore any professional manufacturer should provide a wind design for each and every installation dependent upon the topography, height of building and location in the World.
The European Directive 89/391/EEC - OSH "Framework Directive" was introduced to allow member states to introduce legislation in relation to Health & Safety when working at height. The UK Work at Height Regulations 2005 was introduced under this Directive and requires all those that have a duty of care to ensure that work at height is carried out safely. Solutions need to be suitable and sufficient to ensure prevention of both persons and objects from falling.
These Regulations revoked Regulation 13 of the Workplace Health Safety & Welfare Regulations 1992 and Regulations 6-8 of the Construction Health, Safety and Welfare Regulations 1996.
In relation to Schedule 2 of the Regulations, “Construction Work” (Temporary provisions of protection) states that the top guardrail or other similar means of protection must be at least 950mm high. Toe boards should be suitable and sufficient to prevent the fall of any person, or any material or object, from any place of work. The intermediate guardrail or similar means of protection must be positioned so that any gap between it and other means of protection does not exceed 470mm.
In the UK permanent protection barriers need to be suitable and sufficient and must comply with the Building Regulations Part K criteria in relation to height. As a result, the 470mm gap stipulation would not be possible to achieve. If however the “existing place of work” becomes “Construction Work” then the Work at Height Regulations would prevail and one would need to adopt perhaps toe boards and further intermediate guardrails in order to comply with the 470mm gap.
In other part’s of the World there are other standards that require other criteria in relation to height and loadings. The OSHA regulations require the height of the edge protection system to be 42” (1050mm) with the load applied to the top rail of 200lbs (890N or 90.7kg) in an outwards or downward direction without the guardrail deflecting to a height less than 39” (1 metre). Midrails, screens, mesh, intermediate vertical members, solid panels and equivalent structural members shall be capable of withstanding a force of at least 150lbs (667N or 68kg) applied in any downward or outward direction at any point along the midrail or other member.
The Ontario Building code requires a guardrail system to resist a horizontal load of 50lbf/ft (0.75kN/m) or a concentrated load of 1.0kN (225lb) applied at any point along the top rail. The system also needs to be designed to resist a 1.5kN/m (100lb/ft) load applied vertically downwards. Mid-rails, screens, mesh, intermediate vertical members, solid panels and equivalent structural members shall be capable of withstanding a force of at least 0.5kN (112lb) or 51kg) applied to an area not to exceed 1 foot square in any downward or outward direction at any point along the mid-rail or other member.
A new standard is now being established (Z259.18) for temporary/permanent counter balanced edge protection and timber edge protection used on construction sites.
It is clear that there is a need of interpreting the Standards to establish if a product is fit for use. Many manufacturers will claim compliance to certain standards but what does this mean?
It’s extremely important the manufacturer provides test reports both internal and in some cases external, provides analysis to demonstrate the given system is suitable for the intended use including the roof pitch, membrane, both wet and dry, performance and whether or not the system was tested with or without an upstand.
When we use guardrails in a permanent application (UK & Europe 1100mm high) it may be appropriate to adopt the loading criteria of EN 13374 in relation to the frequency of access and controls in place. A suitably and sufficient risk assessment needs to be completed in order to determine the product is fit for use.
It may not be necessary to use toe-boards or apply the 470mm gap between principal/intermediate guardrails dependent upon the risk assessment. In many instances where a permanent guardrail is required the loadings suggested within EN 13374 may be appropriate as the roof structure may not be able to cope with the higher loadings suggested in the Building Regulations or other standards relating to permanent systems.