Eliminating risk through design

By Nick Atkinson, Director at Ambar Kelly

According to HSE, falls continue to be the biggest cause of fatal injury in Britain’s workplaces. From 2017-18 data, 26% of workplace fatalities – about 37 per year – resulted from a fall from height. On top of this, over 4,000 major injuries are reported to HSE each year by the construction industry, with over half of these serious injuries involving falls from height.  

A riser shaft – a vertical hole running the height of a building and containing its pipework and services – is one of the most perilous areas of a tall building and one of the main causes of falls in the construction industry. If efficient measures are not taken to secure the riser zone, then the threat to worker and occupant safety is extremely high.

As an industry, we have a collective responsibility to create safe and sustainable buildings pre, during and post-construction. Being more proactive and intuitive in our building design, practice and product specification, means we can ultimately eliminate risk. It can be as simple as that.

Yet when it comes to designing the riser zone, the industry is not adhering to this mantra as it should. Too often designers simply show a hazard on their drawings stating: ‘risk main contractor to mitigate’, rather than solving the issue through design.

It is true that many construction and development projects follow an ‘out of sight, out of mind’ philosophy, cordoning off the cavernous riser void with temporary barriers and a sheet of plywood. Whilst this approach might be perpetuated by a lack of education on riser safety, it is still nonetheless compromising worker wellbeing and safety, particularly when the protection provided must be removed or adapted to fit the MEP services.

Consider risers at the design stage

Functioning similarly to the human arteries, risers are a vital part of any multi storey building, distributing MEP services to each area of a building. Although they serve an important purpose throughout a building’s lifecycle, architects and designers fail to consider the riser zone and do not avoid risk in their design.

According to ‘General principles of prevention’ outlined in ‘CDM 2015’ Managing health and safety in construction, dutyholders, including architects, are instructed to avoid risk where possible. But as there are loopholes in this guidance, typically an architect will design the riser’s location but will shift the onus onto the contractor to manage the risk and develop the strategy. Although a riser is part of an architect’s principles of prevention, it is not being included in the blueprint.

Considering the riser zone accounts for 0.1/0.2 percent of a total build’s cost and the only area of a building where all interfaces – plumbing, electrical, water – feed into, it is surprising to see that architects do not consider designing the riser zone when this would ensure safety, reduce costs and protect from the spread of fire.

Moreover, HSE standards indicate that buildings over 18m must have sufficient horizontal compartmentation to prevent the spread of smoke and flame. By casting a secure, steel unit into the riser void, the passage of smoke and flame in the event of fire is prevented. In its permanent state, it provides a solid barrier to fire in combination with fire compound.

A GRP alternative

Although contractors can use GRP grating to prevent falls from height, this grating is installed after the concrete has been poured and requires modification on site, ironically meaning more labour in dangerous locations. Moreover, GRP grating also has high embodied carbon content, which is not a sustainable solution given the UK has now been instructed to meet its net-zero carbon targets.

However by designing the riser zone, as opposed to using solutions such as GRP grating, costs can be prevented. For instance, a recent project, One Crown Place, saved £300k when designing the riser void due to eliminating the work and processes.

By designing the riser zone, multiple benefits can be reaped and risks can be eliminated. If efficient measures are employed to fill in the riser void, then frankly there is no risk of workers falling from height. Although this might seem a simple message, it still needs to be reiterated and circulated around the industry. If the riser zone is a core part of a building, then how long will it be before it becomes a core factor in building design?