Most quality bifolding door systems come with a choice of thresholds.
Typically a good product will have a standard and a low threshold. Other systems come with a selection of two, three or even four different threshold options.
In this article, we explain some bifolding door considerations for thresholds, low thresholds and what heights you can expect. For ease of terminology, we will refer to the main threshold that comes with a bifold as a ‘standard’ threshold and any other variant as a ‘low threshold’.
Why have different thresholds on bifolding doors?
There are several important reasons why bifolding door systems come with a choice of thresholds. The main reasons are to cover most types of applications for where bifolding doors are installed.
Bifold doors are not just fitted in homes; they feature prominently in other buildings such as schools, shops, offices and even as room dividers. For commercial installations, in particular, specifications can vary.
A standard threshold is a common profile that forms a non-modified bifolding door. This is typically the same depth and height as the head and side frames of a bifold. This is most commonly used in the home.
The low threshold can be utilised in the home. However, it comes with caveats. Most systems do not provide a weathered low threshold – that is a lower profile section but with the same level of weathering as the standard threshold. For this reason, you may see bifolding door companies state that the low threshold has no weather rating or should only be used for internal applications.
Bifolding doors are frequently installed inside the home to divide large rooms or in hotels to separate public spaces. In these areas, there is no requirement for weathering. Therefore, a low threshold is ideal.
The other option on a bifolding door is the mobility threshold. This is a ramp type threshold that offers easy access for wheelchairs or for an application where minimal step over and a ramp type threshold may be required. A mobility threshold is widely used commercially but is perfectly suitable residentially as well.
Bifolding Door threshold options and considerations.
One of the most common questions asked about bifolding door thresholds is how the doors connect to the inside and outside spaces and how high the threshold will be.
It is worth remembering that even a standard threshold can be sunk into the floor. When this is done, a minimal 6m, 8mm or 10mm step can be achieved with most systems. Therefore the seamless link is created, internal and external flooring can line up yet there is still a level of weather protection.
The internal and external flooring will largely determine this in many cases.
It is important to check that any illustrations of bifolding door thresholds accurately represent what the finished product will be and are not showing a flat floor detail that may not actually be possible.
A professional bifolding door installer in co-operation with a builder will be able to create the most suitable threshold level. Indeed these two trades frequently work together to create what the customer requires.
Low threshold considerations.
The low threshold is frequently used in marketing materials, but it is worth checking how it applies to each installation.
If bifolding doors are being fitted inside as a room divider to between the house and the conservatory, this is ideal. There will usually be no weather rating with a low threshold, but some systems do provide one, contact us and we can provide further information.
Some installations with a non-weathered low threshold have been carried out on external bifold doors. Generally another method of sheltering the doors is used such as a lean-to roof, a canopy or other method of protection.
While there is little weather protection on a low threshold bifold door, there is sealing. The bottom rails of the folding door panels feature hard wearing weatherstrips or gaskets and these work to create a barrier, prevent draughts and seal the door as best as possible with limitations.