Traditional Roof Demarcation Barriers and Wind Uplift

Traditional roof demarcation barriers on rooftop applications suffer from instability and wind uplift causing them to fly off roofs at wind speeds as low as 50 mph. Guidance on whether your building will be vulnerable to such wind speeds can be taken from two areas:

1: BS6399-2: Code of practice for wind loads.

The BRE confirms that buildings are generally designed for wind speeds with an annual probability of exceedance of 0.02 i.e. a 1:50 year wind speed. If your rooftop demarcation barrier system is intended to be left on the roof for one year or more, it should meet the same design parameters.

2: Met office figures

Given that traditional demarcation systems become unstable at wind speeds of 50 mph, it is worth taking a look at the likely incidence of such an occurrence in the UK. If you take a typical UK urban location e.g. Coleshill in the Midlands, figures from the Met office show that over the past 10 years there have been 77 such events.

Legislation of Roof Demarcation Barrier Systems

D-marc™105 is classed as a form of Collective Fall Protection in accordance with the HSE’s hierarchy of risk management as set out within the Working at Height Regulations 2005 (WAHR). The WAHR 2005 Part 3 illustrate the use of demarcation barriers as an “example of taking other additional suitable and sufficient measures to prevent a fall”. The demarcation barrier system is to be placed a safe distance from the fall hazard (normally 2 m).

A system to provide a safe route to/from an access stair

A system to provide a safe area for regular maintenance.

Health and Safety in Roofwork HSG33 states that 'where work is not done at the edge, demarcation barriers can be provided at a safe distance from the edge. (usually at least 2 meters). Eg work on an air conditioning unit in the middle of a roof.'