Superlintels assessed to give 60 year design life for PFI schools
26 August 2008
With robust data assuring their durability, Superlintels from Jones of Oswestry have been specified to meet the 60 year design life for new accommodation at Northampton School for Girls and other sites within Northamptonshire County Council’s extensive PFI schools building programme.
Designed by architects, GHM Group, with Galliford Try as main contractor, works at the school have comprised the construction in two phases of eight new blocks, due to finish Autumn 2008.
Structural engineers, Jenkins & Potter, specified Superlintels with Duragalv 140 and Duplex finish, Jones of Oswestry’s highest specification protection system giving 60 to 120 years service life, depending on geographic location. Data supporting their performance convinced the project team that they could be confidently used as a viable and cost-effective alternative to stainless steel.
The heavy duty, solid wall SW/HB Superlintels have extra deep sections to support heavy wall loads over long spans, some up to 6.1m, while allowing restraint back to the METSEC metal stud inner leaf. Almost 100 were installed by the brickwork and scaffolding subcontractor, Bliss Brickwork and Scaffolding.
Duragalv 140 provides a minimum 140 micron post-galvanised zinc finish, well in excess of specifications in the hot dip galvanising standard, BS EN ISO 1461, yet required to achieve the higher 60 and 120 years design life categories of BS7543 (Durability of Buildings and Building Components) with local corrosivity rates factored in.
Superlintels are also made from a minimum 4mm thick structural steel plate, providing extra structural strength and promoting the formation of the extra long life Duragalv protection systems.
“Jones of Oswestry’s Superlintels were chosen as they provided the long spans needed as well as the 60 year design life required,” said Tom Wilson of the structural engineers, Jenkins Potter.
Superlintel use on PFI school projects in Edinburgh reinforced their suitability for Northamptonshire CC’s programme.
Data provided by Jones of Oswestry demonstrating Superlintel service life was key in their selection.
The company publishes a product life expectancy chart showing expected Duragalv longevity in relation to the five categories of atmospheric corrosivity identified on the Galvanizers Association Zinc Millennium Map.
Duragalv coatings are also tested and certificated, and all Superlintels are labelled to confirm steelplate and post-galvanising specifications, as well as BS and quality assurance compliance.
Galliford Try design coordinator, Justin Milne, said: “Very few lintel suppliers will guarantee a 60 year service life, but this was paramount in meeting the client’s design life needs and assuring against product failure or maintenance under the PFI contract.”
£200m building programme
The project is part of Northamptonshire County Council’s Private Finance Initiative (PFI) with the Babcock and Brown Consortium of a £200m building programme at 42 Northamptonshire schools, one of the biggest PFI deals in British education.
Galliford Try is undertaking construction, and Amey will take on facilities management for the duration of the 27 year contract. Building work started in 2005 and is due to finish at the end of 2008.
Jones of Oswestry’s Superlintels have been specified for other sites, including Duston Secondary School, Woodvale Primary School, Mereway Community College, Northampton School for Engineers and Kingsthorpe Grove Primary.