Interpretation of Part K ‘increasing cost and risk’

The interpretative nature of specification under Part K is leading to wide variations in specification of IGUs and balustrading, according to Cornwall Glass.

The south west-based glass processor said that, in its experience, requirements under Part K: Protection from falling, collision and impact, can be interpreted “wildly differently” by individual building control officers.

This means that in many cases product is being over-specified, artificially inflating costs.

It also means that some specifications are falling considerably short of loading and containment requirements, representing a risk of injury and death.

Ceawlin Hickman, estimating and technical representative at Cornwall Glass, said: “Part K, in common with some other areas of building regulations, sets out the requirement for loadings in specific IGU and balustrading applications but isn’t explicit as to how they’re to be achieved.

“This means it’s down to interpretation of requirement, which in our experience can be wildly different from one control authority to the next. It also means that installers, builders and structural engineers are frequently defaulting to a catch-all specification, which can artificially inflate their costs compared to those of their competitors.

“Much worse, they’re not getting it right and putting lives at risk.”

Ceawlin highlights a recent incident where a Juliette balcony without a head rail was signed off by a building inspector having used only a single sheet of 10mm toughened glass.

“As a minimum it needs to be a 21.5mm toughened laminate,” Ceawlin stated.

“There are significant differences in requirement if it’s a u-channel or post and rail system, and the industry and building inspectors are not necessarily always tuned into them.”

This, he warned, was another key challenge in specification of large IGUs, including applications in floor-to-ceiling installations with requirements for containment (as specified in Part K) frequently overlooked.

“Installation of a 2,000mm x 2,000mm or 4m2 plus IGU requires much more consideration than simply handling,” Ceawlin said. “You need the right specification of glass, something which introduces greater challenge the bigger you go.”

Over-sized units are now a standard part of Cornwall Glass’ production run. These are, for the most part, manufactured at Cornwall Glass’s purpose-built IGU and processing factories.

“We’ve seen growth because we work with our customers to get specifications right,” Ceawlin said. “Sometimes that’s meant working with them to take building control through specifications of IGUs or balustrading to explain how products meet Part K.

“That doesn’t by default mean always moving to a laminate, something which can deliver significant savings on larger contracts.”