Wastewater Treatment Peaceheaven
Rockwool’s Hardrock Dual Density range of insulated roofing boards are the key component in the construction of the green roof at Peacehaven Wastewater Treatment Works. The roof has been designed to both enhance the scheme’s sustainability credentials and to help integrate the project into the surrounding landscape
Waterproofing Specialist: Alumasc
Envelope Contractor: Prater Ltd
Challenge
The giant, curving, grass-covered roof at the Peacehaven Wastewater Treatment Works is the largest of its kind in the UK. Beneath its grassy expanse the roof conceals various buildings that form part of Southern Water’s £300 million environmental improvement scheme constructed to treat 95 million litres of wastewater a day and bring cleaner seas to Sussex. The roof’s curvaceous profile and cantilevered construction have been designed to enable the treatment works to blend in with the rolling downland hills that form the spectacular backdrop to the site.
Success
The 17,800 m2 roof’s construction was fundamental to the project’s success. In addition to helping integrate the treatment plant into the landscape, the roof’s grass-covering will enhance the site’s biodiversity by providing a habitat for downland plant species and create a secure environment for nesting birds. It will also help attenuate rainwater run-off and offer excellent thermal insulation.
Rockwool’s consultancy approach
The treatment plant is being built by 4Delivery, a consortium made up of Costain, Veolia Water and MHW. To develop and deliver the most cost effective, sustainable roofing solution, Rockwool’s insulation consultants worked with waterproofing
specialist Alumasc and envelope contractor Prater from concept through to completion.
Beyond insulation
“Given the complex shape of the roof, Rockwool was the most suitable product
because it offered a degree of flexibility.” Paul Webb, Project Manager, Prater.
The sustainable roof’s construction is based on a warm flat roof system using Rockwool’s 85 mm Hardrock Dual Density range of tissue faced insulated roofing boards. These are manufactured using Rockwool’s unique dual density technology, which includes a robust, high density top layer to provide improved point load compressive resistance. As a result, the boards provided an ideal non-combustible, acoustic and thermal insulation solution, which was compatible with
Alumasc’s Derbigum Anti-Root, high performance roof waterproofing membrane. A green roof system was installed on top of the waterproofing.
“The advantage of using Rockwool is that in addition to its recognised properties, its use in conjunction with Derbigum provides an extremely durable and long-term waterproofing solution.”Trevor Lang, Alumasc.
The roof was constructed using a profiled metal deck, supported on purlins and covered with a vapour control layer. On this project part of the roof’s profiled metal deck was built and installed upside down after one particular batch was supplied with the finish on the wrong sides. The result of this upside-down construction was that the troughs in the profiled metal decking were spaced wider apart than usual.
To keep up with the short build programme, Rockwool’s consultants applied their technical expertise to prove that the Hardrock Dual Density insulation was suitable for the deck’s unusual profile without compromising its performance.
In addition to roof insulation, Rockwool insulation products have also been used in the construction of the scheme’s walls. The walls are constructed from green-coloured, ribbed metal cladding, designed to blend with the surrounding landscape. A flexible mat of Rockwool Cladding Roll was used in the lightweight wall’s construction to satisfy the designer’s thermal, fire and acoustic requirements.
Benefits
Rockwool is one of the most sustainable insulation products available making it the ideal material for use in the construction of the new wastewater treatment works. The insulation is made by melting naturally occurring volcanic diabase rock and recycled
briquettes. During its long lifetime, a typical Rockwool insulation product will save more than 100 times the energy invested in its manufacture, transport and ultimate disposal. At the end of the wastewater treatment works’ life, the insulation can be removed and returned to the factory for recycling.
