For customers choosing bifold doors for their project, the dream is to slide back the doors and create a step-free connection between inside and out. Bifold doors are perfect for completely opening up an aperture and for extending your living space out into the garden on warm sunny days and can be a real centre-piece for a new extension or renovation.
With many projects, the ambition is creating a flush finish between your home and patio and to do this bifold doors can be designed with completely flush tracks – however, in many circumstances, this isn’t something we would normally advise.
In order to create a completely level threshold between inside and out, the panels of the bifold doors sit above the track rather than sealing against it.
On flush tracks this means that the only connection between the base of the panels and the floor itself is a piece of brush pile, not a problem if you are installing the doors internally or if your external set of doors are connecting your house with a small, very sheltered courtyard garden.
However, for those customers with a garden that is exposed to even moderate breeze, brush pile does not allow for an effective weather-seal and as such you run the risk of allowing drafts from under the doors into your home.
It depends on where you live. For those in urban or sheltered rural areas then we would recommend the low-threshold SUNFLEX bifold track option.
Rather than being completely flush between inside and out, the low-threshold track is designed with a 14mm upstand on the inside of the track that enables the inside frame of the doors to create a single tight seal when it is closed.
The upstand is high enough that it will keep out drafts, but low enough that it is almost an invisible when viewed from the inside. Indeed the 14mm height is low enough that it is considered a level threshold under both Building Regulations Part M and the Disability Discrimination Act.
We would class an exposed location as being one which is particularly prone to frequent strong winds, whether that is because of its coastal location, its elevation above sea-level or remoteness. In those locations we would strongly recommend a fully weathered track to provide the ultimate protection from wind and rain.
The SUNFLEX weathered track is designed with upstands on both the inside and outside of the track, allowing both the inside AND the outside faces of the bifold door panel to seal against the track – creating a double seal.
With the weathered track the SUNFLEX SF55 and SF75 aluminium bifold doors are independently tested to the highest standards of weather performance of any bifold door on the market. In the air permeability test (standard BS EN 12207) the systems achieve a Class 4 rating of 600 Pascals, whilst the water tightness test (standard BS EN 12208) the bifold doors achieve Class 9a rating at 900 Pascals.
For more information about weather performance testing of door, read our blog.