Two lightweight construction systems developed by Knauf Drywall – one of the UK’s leading manufacturers of lightweight building materials and systems – are being employed to build one of the country’s latest Energy from Waste plants; and so accelerate construction and reduce costs while meeting the strictest standards of fire protection.
The contract to design, build and operate the Energy from Waste (EfW) facility at North Hykeham was awarded to WRG by Lincolnshire County Council after a detailed procurement process and is now being built by main contractor Clugston Construction. The project comes on the back of similar success for Clugston, who have another in the pipeline in Staffordshire, in addition to two further opportunities being worked on. The facility, which is part of a £145m investment, will treat up to 150,000 tonnes of household waste per year and will produce enough electricity to power over 10,000 homes and businesses.
Working in collaboration with Clugston’s chosen subcontractor Specialist Global, Knauf Drywall devised two lightweight alternatives that not only improved health and safety on site and but also met the robust fire resistance requirements set by the insurance companies involved. Knauf Drywall’s Shaftwall simplified the installation of the three-storey liftshaft while its 30m Steel Frame System (SFS) provided a fire-proof and weatherproof option that was far lighter than the concrete block equivalent.
“Working with Knauf Drywall we have been able to offer a lightweight construction solution to providing two-hour firewalls,” explained Paul Caunce, managing director of Specialist Global. “We have produced a unique technical response that satisfies the requirements of both the international standards governing this type of plant and the standards demanded by the insurers for the project, which have a particular interest in the protection afforded to the asset.
“This lightweight solution also brings huge indirect cost savings as well as technical benefits. For instance, you don’t need as substantial foundations so the depth of excavation required is significantly reduced.”
The facility is designed so that the bin lorries deliver the refuse to the incinerator by driving beneath the three storey office block, so the ground floor office is 6m above ground and the top storey is 20m above ground. The offices were built first and are accessed by a lift with the liftshaft being built and lined with Knauf Shaftwall, complete with an extra thermal lining and sheathed in Knauf Aquapanel Exterior, which provided a weatherproof exterior that kept the offices watertight while the plant itself is being built.
Knauf Shaftwall is an innovative system to form enclosures around service and lift shafts while working from one side and so improving health and safety while reducing the requirement for expensive scaffolding and craneage. Using this system it is possible to provide fire resistance of up to two hours. Knauf Aquapanel Exterior is an aggregated Portland Cement building panel with polymer coated glass fibre mesh embedded in both surfaces that provides a fast-track, all-weather cladding.
“The Shaftwall product enabled us to get around some issues we had with restricted access so we could build the wall from the office side,” explained Roger Snell, senior project manager for Clugston. “The Aquapanel was effectively an internal wall that was exposed to the elements and so we could get on with building the admin offices knowing the offices were weatherproof.”
The plant itself is a massive building standing 44m high, with the 20m high wall separating the office from the waste and the incinerator being built using a Steel Frame System with Knauf Fireshield and Aquapanel Exterior rather than precast concrete blocks. The result is a far lighter construction – 60kg/m2 rather than the 250kg/m2 for a concrete block wall performing the same function – speeding up construction time and removing the need for footings.
“The building’s design is such that the wall doesn’t need to start from the ground but from the first floor offices, which are 6m above ground,” said Roger Snell. “The system enabled us to fit the wall without needing to bring it to the ground for support and to install it around columns and bracing that would have been unfeasible using precast concrete and blockwork.”The Knauf Fireshield range of premium plasterboards contains special additives that increase core adhesion at high temperatures so that, as part of the Knauf Encasement system, the board can provide up to two hours’ fire protection to structural steel columns and beams. The Knauf Aquapanel Exterior provides waterproofing which is not only important for weatherproofing the building during construction but also for withstanding the blasts of water cannon – a necessary fire precaution for an incinerator dealing with thousands of tons of refuse.