James Gooder of SFS Fall Protection Systems explains what specifiers need to consider when designing for safe working at height
The ability to be able to design-in safety gives assurance to those tasked with maintaining the building envelope. This includes gutter clearing and air conditioning unit, plant or machinery maintenance, as well as the installation or maintenance of solar or photovoltaic panels and green roofs. But every application is different, so it is important to understand the key specification questions and tailor the approach for each project.
Within the area of ‘fall protection systems’, specifiers will have options for horizontal, vertical and overhead lifeline systems. This enables designers to provide reliable fall protection throughout the building’s lifespan for anyone who needs to ascend the structure, stay safe while working at height – typically on a roof – and then descend safely. The most commonly requirement is a horizontal lifeline (HLL). This typically comprises top fixed shock-absorbing posts anchored to the outer roof skin, joined through a series of components to create a system using 8 mm wire cable. While some systems can be installed directly to the building structure by utilising in-line shock absorbers in place of shock absorbing posts, solutions that attach securely to the outer skin offer significant benefits.
The process of designing an HLL system starts with understanding the requirements of the user and the need for roof access. This should be done by fall protection experts, consulting with the architect, building owner/client and main contractors to prioritise safe working methods within CDM.
The proposed design must consider the access point and method, the number of users per system, roof substrate/build-up, and method of fixing. Crucially, the design must take into consideration the hierarchy of fall protection. Restraint systems are the preferred option, and an arrest system should only be offered as a last resort. While all systems must be capable of arresting a fall under EN795:2012 ‘foreseeable misuse’, it is best practice to keep staff in restraints to prevent any possibility of a fall occurring. HLL systems have moved on from the ugly ‘through fixed’ rigid posts that had to be fastened back to structural steel through the roof build-up – often leading to weathering issues. System end loads would be significantly high and shock-absorbing elements could only be added ‘in-line’.
Today’s engineered solutions are fundamentally different, with no need for ‘through fixed’ posts. HLL posts can be fixed to the roof skin, whether it be a standing seam, a flat roof construction or corrugated sandwich panels. These systems accommodate the lighter weight substrates featuring thicker insulation, complementing materials advances without compromising structural integrity or user safety. Built-in shock absorbing technology reduces deployment loads to the structure to under 6 kN. Designed to withstand stresses exerted by snow and ice build-up and resist corrosion, posts can minimise the forces that rivets or fasteners would be subjected to in the event of a fall. This spreads and dissipates the impact of multi-and single-user falls and prevents roof damage to the roof structure.
Corrosion is one of the biggest threats to the integrity of any lifeline system. It has the potential to cause failure of the system when it is needed most, and can cause unsightly rust stains on roof sheets. The application of protective surface coatings to carbon steel elements only provide temporary protection. Safety lines are exposed to the weather 365 days a year, 24/7 for life, and any loss of performance can be catastrophic in a safety line. That’s why EN 795:2012 requires all components to be subjected to neutral salt spray tests in accordance with EN ISO 9227 for 48 hours+.
A combination of both A2 (grade 304) and A4 (grade 316) stainless steel is the best way to deliver peace of mind that the system will have a lifespan matching the building life.
James Gooder is business unit manager at SFS Fall Protection Systems