Over the past decade many prefabricated roof systems have come to market, bringing benefits of speed and safety of installation, and improved U-values.
Production has fallen in line with the decline in housebuilding and, while it will recover as housing starts pick up, some trussed rafter manufacturers think roof systems will remain a niche product, not least because of their design limitations.
“We’re keeping an eye on them,” said Scotts of Thrapston chairman David Scott. “We can manufacture smartroof if our customers want it but, as a personal view, I don’t think there’s one roof system that has the lead over the others at present. They’re not as exciting as they should be.”
Attic trusses had the flexibility to achieve a similar outcome, without the weight of a roof system, he said.
“I don’t think the benefits really outweigh the difference from what roof trusses do,” said Mr Scott. “Trussed rafters are tried and tested. People are comfortable with them and there’s flexibility where you can have part of the roof cut.”
Roof systems had their place, especially in social housing, but they wouldn’t have a great impact on the market, he said.
Jonathan Fellingham, managing director of Donaldson Timber Engineering Ltd, agrees that panellised systems have their niche but roof trusses will always be the market leader.
“Panel roofs are fairly limited in terms of what roof shapes you can get,” he said.
James Donaldson is a smartroof licensee but it would not be producing any “until demand is considerably higher,” said Mr Fellingham.
About 12 years ago Minera Roof Trusses stocked SIPs roof panels and had a model set up at its facility but interest was limited.
“Some people came to view it as a possible solution. They saw we were making attic trusses and when their enquiry came in it was for attic trusses, not SIPs,” said managing director Mike Whear.
He also identified panels’ lack of flexibility as a limitation. “They’re alright for gable to gable roofs but that’s about it. It would be a solution for social housing but I still question whether it’s cheaper than attic trusses because manufacturing is more expensive,” he said.
Pasquill managing director Stuart McKill said cost comparisons are hard to quantify.
“The products are generally more expensive than trussed rafters, which is expected but, in terms of full cost analysis, it’s hard to put a stake in the ground as to where one starts and finishes in terms of erection, installation and additional benefits in terms of speed and health and safety,” he said.
However, as the bar is raised for airtightness, offsite manufactured products could provide a better guarantee on the overall performance.
“You can guarantee a system as opposed to a component so the warranty aspect is valuable,” said Mr McKill.
He estimated that panellised roof systems accounted for around 2% of the market and had the potential to grow to 5-10% share.
