CONSTRUCTION SAFETY AND WELLBEING

Across UK construction, the fatal injury rate on-site remains stubbornly steady at around 40 deaths per annum (roughly four times the all-industry rate).¹ Around 82,000 workers a year suffer from work-related ill health and after asbestosis, silica dust (typically from working with concrete, sand, bricks, blocks and mortar) is the second greatest risk to health resulting in the additional deaths of over 500 construction workers in 2005 alone.² Aside from the tragedy and human costs of such, annual costs to the industry for ill health and injury are estimated at £1.06 billion with 2.4 million lost days of work per annum.^3,4

The situation can be quite different when building with CLT elements.

Fabrication work is displaced from sites to a controlled factory environment and construction is much quicker with significantly reduced site programmes. Site logistics, sequencing and panel assembly can be planned, refined and communicated using 4D tools and existing BIM data with no need for on-site ‘fitting’ so risks can typically be considered in advance and designed out or better managed. Vehicle movements are hugely reduced with a fraction of the number of deliveries (benefitting site operatives and the general population).

Panels are typically installed by small specialist teams trained in working at height requiring far fewer workers on site. Manual handling of heavy materials is virtually eliminated and lifting directly from a trailer minimises the need for double handling panels (a panel lift of up to 50m² might be completed in 20 minutes). Teams typically work in isolation from other trades with few interface issues, hot works are eliminated and little cutting is required – limited to the smallest openings or possible bracing left in situ for transportation. Fixing processes are relatively simple with less equipment and fewer tools required. As such, projects can be managed and overseen more effectively which is particularly beneficial for dense urban sites or multi-phased and complex projects.

The use of CLT limits, or offsets, many other significantly more hazardous operations, whether they involve materials of higher mass or those harmful to health (such as cement and concrete or gypsum board) and reducing working at height (itself responsible for around half of all annual site fatalities). There are well understood risks from wood dust,⁶ but these, like other risks, are best controlled in a factory environment where all processing and finishing is undertaken by machine, avoiding on site working and modification of panels.

The risk of workforce harm across the project life cycle is also reduced. Follow-on trades can usually begin work straight after installation of panels within a significantly improved working environment. A weather-tight envelope can be achieved rapidly and CLT provides a degree of insulation before a shell is complete. Working with a CLT substrate involves screwing fixings directly into timber rather than drilling into steel or concrete and as a consequence sites are quieter with reduced dusting. End-of-use risks are also reduced: CLT can be readily designed for disassembly and if elements cannot be unscrewed, there will be no need to demolish or cut reinforced concrete or steel.

Edge protection for upper floors may be fitted before panels are lifted above ground and scaffolding is not required for CLT installation. Panels forming outer walls can provide workforce protection and temporary protection can be easily fixed to panels and readily modified to suit changes on site.

The challenge for teams remains communicating such benefits to decision makers when making comparisons with other forms of construction.

FIRE SAFETY DESIGN