Decalu88 does it with double
The Decalu88 bi-folding door from Deceuninck Aluminium achieves U-values of 1.2W/m2K with double glazed units, comfortably meeting new requirements for newbuild as well as home improvement under Part L from June this year – without using triple glazed units.
From June 2022, replacement doors with a >60% glazed area will need to achieve an overall U-value of 1.4W/m2K, while newbuild equivalents will need to achieve an overall U-value of 1.2W/m2K.
When the Future Homes and Buildings Standard comes into force in 2025, these figures are expected to drop even further.
According to Deceuninck Aluminium, many aluminium systems will have to rely on a triple glazed unit to meet the new revisions, which impact the overall design of the door.
“Older systems were designed for a double-glazed unit, so there’s a maximum width of unit you can get into the frames,” said Nigel Headford, director at Deceuninck Aluminium. “So, the question is not about the number of panes of glass, but how deep you can go, and with older systems you are typically limited to a 28mm-32mm unit.”
If a triple glazed unit was used to improve the thermal performance, consideration would also need to be made for the extra weight placed on the hardware.
“Most bi-folding doors on the market have a maximum weight of 100kg-150kg,” Nigel said. “So, if you are going to put in triple glazing then you are probably going to go over that maximum weight, which is going to limit the size of the door.”
The Decalu88 bi-folding door is also designed to comfortably incorporate thicker and heavier units to meet future thermal, acoustic and security standards. Each sash is able to accommodate weights of 200kg and up to 3m in height. It has also been tested to PAS24 at 3m tall.
“It also features a 7mm fully adjustable jamb on each side of the door, simplifying squaring and setting,” Nigel said. “And a knock-in glazing bead with pre-inserted and co-extruded flush gasket, means you can glaze each sash in less than four minutes and fit a door in as little as an hour.”
