What Are External Bifold Doors?

If you’ve been following trends in home improvement, you might have noticed that one particular home update has exploded in popularity over the past few years. We’re talking about the external bifold door, examples of which can be found linking patios and living spaces across the country. The unusual construction of these doors affords them several advantages over their sliding and French counterparts.

But exactly what is an external bifold door? In this article, we’ll take a closer look at these popular patio doors, how they work, and whether they’ll make a good fit for your home.

What Are External Bifold Doors?

A bifold door is made up of several panels, attached to one another via a series of alternating hinges. This arrangement allows the entire thing to open and close in a concertina. External bifold doors separate the exterior and interior and are seen at the rear of the property. They allow lots of natural light and air to flow freely into the home when the doors are open, making them a perfect addition for warmer months. External bifold doors tend to be used as type of patio door. 

The construction of your folding door will differ depending on where you’re thinking of installing it. An external bifold door will need to be built in such a way that they can repel the elements

External Bifold Door Materials

As with most varieties of door and window, you’ll have a choice of three different materials to consider. Let’s run through them.


Timber doors offer a look that other materials cannot replicate. Oak is a classic choice – given proper maintenance, it’s durable enough to last for years, and the grain is densely packed and gorgeous. With the application of a suitable finish, it will look incredible. Timber doors need occasional maintenance if they’re to look their best – the fibres will soak up moisture and warp if they’re not protected by a layer of protective wax or oil.


Aluminium is another popular choice. It’s expensive, but it’s also immensely strong. Aluminium frames can be made much thinner than those made from other materials, while still supporting the same amount of glass. The result is a door that allows much more natural light into the home. Aluminium doors are powder-coated with a layer of protective paint at factory level, and thus don’t need to be maintained by the homeowner. They provide a contemporary look that’s great for many modern homes. It’s also highlight energy efficient and weather proof. 


Finally, we have unplasticised poly-vinyl chloride. This popular material is the same stuff that faux-leather clothes are made from, except that it hasn’t had plasticising agents added. This makes it extremely rigid and naturally moisture-repelling. Once it’s set, uPVC can’t be modified, which means that you’ll have to decide on your locks and other features at the outset. uPVC can’t be modified, sanded or painted, and the attempt to do so can often ruin the door. It’s also the weakest material available, which means that the frames must be made suitably chunky to compensate.

The panel at one end of a set of bifold doors comes with a pin sprouting from the top and the bottom, which slots into corresponding holes at the top and bottom of the frame. The panel rotates around this fulcrum, and entire door thereby opens and closes. Additional panels can be folded in a concertina style to provide a door that neatly folds away to open up your interior. These panels are attached via a track which keeps them in place.

Can bifold doors open inwards?

Let’s again consider how bifold doors open. Every other hinge is attached to a movable carriage, which runs along a track. The position of this carriage on each panel will determine whether the door opens inwards or outwards. You’ll be able to reverse bifold doors to alter the direction in which they open, which means you’ll be able to decide which way around you’re putting yours immediately prior to installation.

Do bifold doors need a track?

All bifold doors need a track for two reasons. Firstly, they’ll need to be prevented from swinging all the way outward. Secondly, (and more importantly) the track bears the weight of the door and prevents excessive strain from being placed on the pivot pin.

If you’d like to disguise your track, you can have it set into the floor. This will decrease the likelihood of anything settling into the gap. You might also elect to suspend your door from a ceiling-mounted track, thereby allowing the floor beneath the track to be seamless and uninterrupted.

Whichever sort of track you choose, you’ll want to keep it clean, lubricated and free from detritus. Apply some WD-40 every so often and run the door back and forth.

What different types of bifold door are there?

When shopping for bifold doors, you’ll have three different formats to choose from. The first and simplest is to have a single long set of panels. This is known as an ‘x+0’ configuration, where x is the number of panels.

If you’d like easy access to the exterior without the need to open the bifold, you might opt for an ‘x+1’ configuration, which incorporates a single door at the end, known as a traffic door. Through this door, you’ll be able to move in and out of the building during winter, without allowing all of the warm air in your house to leave. If your set of bifolds is unusually large and doesn’t have a handy alternative door nearby, then opting for a traffic door makes a great deal of sense.

Finally, we have the ‘French-fold’ variety, which incorporates two identical sets of panels which unfold from either side of the frame to meet in the middle. They combine the visual style of French doors with the spectacular size and looks of a set of bifolds.

What Size Are External Bifold Doors?

The construction of an external bifold door means that they can be made extremely large. Some are as wide as five metres; others are wider still! As such, they’re able to replace entire walls, creating a seamless transition between the interior and exterior of a property when open. Aluminium, being stronger, can support a greater weight of glass, and thus it’s what the really big bifold doors tend to be made from.

The minimum size for a bifold door tends to be around 1800mm. A door of this sort would consist of a trio of 570mm panels, which are the smallest variety available. As we move up into larger doors, the panels get wider and more numerous. You’ll have a choice between a large number of narrow panels, or just a few extra-wide ones. The maximum size for a bifold door tends to be just under five metres.

What height are bifold doors?

For the most part, bifold doors are as tall as any standard door in the UK, which is around 2090mm, or 2105mm for the frame. It’s important to stick to millimetres when measuring your opening, as even the smallest gap around the edges can lead to considerable draughts. You’ll need to account for a fitting tolerance of around ten millimetres when you measure up the opening.

Are Bifold Doors a Good Idea?

Given the sudden popularity of bifold doors, you might be forgiven for thinking that they’re a flash in the pan. How do they compare to the equivalent French or sliding doors? And are there any downsides that we haven’t considered? In short, are bifold doors worth it?

How Much Value do Bifold Doors Add?

Bifold doors usually recoup the cost by immediately adding value to the home. If you show a prospective buyer around a kitchen/diner area or a lounge, then the sight of an eye-popping set of folding doors is certain to leave a lasting impression. The extra light they bring into a home can also change the feel of the indoor space to make it more enticing. It’s difficult to estimate precisely how much value a set of external bifold doors will add to a property, but the effect will almost always be a positive one.

Why are Bifold Doors Better than Sliding Doors?

Since bifold doors collapse into a concertina, they can open out much more fully than sliding doors, which cannot shrink any further than the width of a single panel. As such, bifold doors are far more capable of expanding an interior living space onto the patio and creating a seamless transition from indoors to outdoors.


External bifold doors are a popular means of opening up an interior space and connecting your home to your garden. Their construction allows them to be made larger than any other variety of door, and thus they’re capable of forming the ultimate visual centrepiece for your home and garden. Get an external one, and your summer barbeques will never be the same again!