How to get a low bifolding door threshold

The bifolding door threshold is one key feature of all folding sliding doors. This article explains the different threshold options available with a bifold. We also give you some product advice on bifolding doors giving you several bifolding door threshold options.

The bifolding door threshold and why it matters

Every door has a threshold of some description, whether standard, low or even a zero threshold on internal doors. Not only does a bifolding door threshold provide weather and water protection. In some cases, it’s also required for convenience. Two examples are helping the disabled transition through a doorway easily, or providing easier use for pushchairs.

For bifolding doors, the threshold doesn’t just provide weather protection. It’s also an area housing the bifolding door rollers and guides at the bottom, holding the door panels securely in place. At the same time, opening the doors must be a smooth and easy operation. Again the threshold provides a suitable track, letting the panels fold and slide to the fully open position.

Moreover, designing your bifolding doors means considering the type of threshold you want. Many people simply want the best possible look, often meaning the interior floors are flush with the threshold and then the outside decking or slabs. Therefore, aesthetics are important for bifolding door thresholds whilst also creating that desirable seamless link between the inside of your house and your garden.

Bifolding door threshold choices:

Most common door thresholds on all types of doors have a rebate.  This is an upstand that is designed to create a physical barrier against any water entering the inside.  It also plays an important role in keeping the doors sealed.  This rebate can also be seen around the rest of your door frame and it is what the door shuts against.  Typically you may see some kind of rubber, nylon or brush seal there as well to further aid air and water ingress.

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The images below illustrate the popular threshold arrangements for bifolding doors. These images illustrate what’s available with the best-selling Origin brand of bifolds and how they interact with the internal and external floor levels.

The standard threshold

Bifolding doors coming with a standard threshold typically have a standard installation. This type provides all the required weather and water protection. Furthermore, it comes with a small ‘upstand’ providing a suitable barrier to the elements.

When replacing an old set of doors with a bifold, the standard threshold provides the simplest installation. New openings mean your installer working with your builder or architect. Here, it makes sense for the builder to be familiar with the dimensions and design. It ensures he provides a suitable opening for the doors. Therefore, ensure all parties involved with the project communicate on this detail of any new set of doors.

The good news with a standard threshold is this too can sit lower. Typically this involves removing a course of brickwork at the bottom, enlarging the opening, and setting the new doors lower. Working with a good installer is essential. Contact us for details of where to buy in your area.

The interior low threshold.

With many bifolding doors used internally as room dividers or partitions, there’s an interior or low threshold. Most bifolding doors offer this option. Bear in mind it’s for internal use only and there’s no weather or water protection.

low bifolding door threshold in a new extension

The ramp-type bifolding door threshold

Less known, but worth considering is the ramp-type design. First of all, this threshold provides excellent accessibility for the disabled or wheelchair users. Therefore it’s perfect for bifolding doors in commercial environments such as bars or restaurants.

Another advantage of the ramp-type threshold is a significantly simpler way of getting a low and near-flush design without the modification work on an existing opening.

The only drawback to this design is it’s not as attractive as a regular flush or low threshold. As these are designed for higher traffic they usually only come in a silver or ‘mill’ finish. But do check out products available with this design as it may work for your particular property and requirements.

Most ramp type threshold offer a level of weather rating. Do not expect this design to have the full weather protection of the standard threshold design.

Furthermore, the weather testing to British Standards that reputable manufacturers adhere to is always carried out with a rebated threshold. This is because rebated thresholds have the seals and design in place to prevent water ingress to required standards.  Low thresholds do not.

Bifolding doors with the best threshold options

Where most bifolding doors only come with one or two options at the threshold, here are some brands offering up to five different solutions. These are just some of the better bifolding doors on the market designed with the user in mind. Other models may be available.

The Solarlux Bifolding Door

One of the best bifolding doors on the market is the Solarlux brand. Made in Germany, superior in design, not to mention one of the slimmest bifolding doors on the market.

Solarlux bifolding doors come with six different threshold options, depending on the model. These range from tracks recessed into the floor, those with an access ramp, fully flush and a minimalist version. There’s even a track illuminated with LED’s.

aïr800 folding sliding doors

Bifolding doors with low thresholds normally have no recognised weather rating and are intended for internal applications such as room dividers.  Air bifolding doors are another example of a high end bifolding door, with a selection of threshold options and with a weather rating on the low versions.

Schuco ASS70 FD and ASS70 FD HD bifolding doors

Both the standard and heavy-duty Schuco bifolding door versions come with a choice of thresholds to suit the application. They are therefore suitable for both internal or external applications.

The latest ASS70 FD HD has the same options, however this door is truly special in allowing bifolding door panels up to an incredible 1.5m wide each.

Sunflex SF55 and SF75 folding sliding doors

Made in Germany, slim, contemporary and with excellent specifications. Sunflex bifolds also come with a ramp type threshold for easy access in non-exposed locations as well as two further options for more standard floor designs.

Reynaers bifolding doors

Available with the Reynaers bifolding door are four different threshold options. These comprise flat, low and a slim or standard weathered version.

Smart Systems Visofold 1000 and 6000

A more affordable alternative and still an excellent choice are either the older Visofold 1000 bifolding door or the super-slim newer Smart Systems bifold.

Alumina bifolding doors

The Alumina bifolding door is unique in having a foiled woodgrain or plain finish making it excellent for matching PVCu windows or as a stand-alone bifold, single, or set of French Doors. This bifolding door brand also comes with a low ramp-type threshold, also having a weather rating.

solarlux bifolding doors
A Solarlux Bifold Door with open corner and flush threshold

Understanding the cill used with bifolds

The cill is a separate aluminium extrusion similar to a window cill you see externally.  The bottom of the door sits on top of the cill that is designed to project water away from the brickwork underneath the frame.

Most installations rely on a cill and the sizes and types vary. A competent installer following a survey, establishes the most suitable type for your installation.

Tips and advice choosing a bifolding door threshold

Always work collaboratively with your builder and bifolding door installer. Ensure those building any new opening are familiar with the bifolding door profile and it’s dimensions. A good installer can bring a sample of this as well as provide drawings.

When properties are built from new with bifolding or sliding patio doors, the builder will already have created a level threshold to comply with building regs. So your builder is having to work a little harder to overcome an existing entrance that is not level.

Consider the bifolding door track design early in your research. This avoids costly mistakes further down the line.

The location of your doors also affects performance and the bifolding door threshold option available. Doors in very exposed locations need extra care. In these situations you’ll get the best performance using a fully weathered version.

Low or flush thresholds are usually available for other door designs such as opening in bifolds, open or fixed corner designs.