Aluminium bi-fold doors or aluminium sliding doors – The pros and cons.

Decisions, decisions...

With so many different products out there, our customers face many decisions when purchasing new windows or doors. In this short article, we look at probably the most common of these decisions; aluminium bi-fold doors or aluminium sliding doors?

Whilst we do install uPVC sliding doors for our customers, far more commonly we install aluminium sliding doors. With regard to uPVC bi-fold doors, we can install them but we tend to actively dissuade our customers away from them. Bi-fold doors are built in such a way that each pane operates in conjunction with the others and that the hinges are all connected and in between each pane. This means that for the doors to operate well generally, the uPVC profile must stay in place and rigid. Where uPVC is not as strong as aluminium, there tend to be many more maintenance issues with uPVC bi-folds than their aluminium counterparts. This is why we only really install aluminium bi-fold doors.

We’ll now take a look at the key differences between sliding doors and bi-fold doors in order of how important they appear to be to our customers.

Aesthetics – glass or frame?

Probably the biggest pull towards our sliding doors is the higher glass to frame ratio possible. That is to say, in a sliding door, you get more glass than you do than you do in a bi-fold. Our Smart Visofold 1000 and Schuco ASS70 FD bi-fold doors can go to 1200mm per pane but our Smart Visoglide Plus and Schuco ASS70 HI lift and slide doors can go to over 3 metres wide per pane!

See below photos of bi-fold doors and sliding doors in approximately the same size opening. Sliding doors tend to win if this aspect is important to our customer.

Black aluminium sliding patio doors and window

Sliding doors – more glass

Bi-fold doors – less glass

Grey aluminium sliding doors and grey windows

Fully openable

Many customers are set on bi-fold doors right from the start because they have visions of fully opening their new extension. The picture below sums this vision up. It is the seamless transition from inside to outside.

As they do not fold, sliding doors on the other hand, can never be fully open like bifolds can. See below image showing an installation we did in Whitstable.

Bi-fold doors or sliding doors

We do always make sure we remind our customers that the Great British weather does not make it easy to fully open bifold doors very often!


Cost is roughly the same unless the doors get big. If they get really big, sliding doors in few panes become significantly more expensive because big single units of glass are very expensive. It is really only possible for us to put each one through the system and see where they come out.

Ease of in and out access

A tick in the box of bi-fold doors is how easy they are to quickly nip in and out of with their traffic doors. Although in certain configurations it is not possible to have a traffic door (see below), many popular configurations do feature one.

The idea of being able to quickly open the traffic door like a normal back door without having to slide a sometimes heavy pane across to nip out into the garden is a feather in the cap of our bifolding doors.

Golden rule for bifold doors configuration

Thermal values

All of our products comply with the relevant Part L of building regulations when it comes to required u values and energy ratings. As would be expected, some of our products perform better thermally than others. For straightforward ‘refurb’ work (where we remove old window/door and replace with new one), our customers are often not really interested in the thermal values. However, for extensions or new build homes we are involved in, thermal values and SAP calculations are always an important aspect. Our customers’ architect often specifies a u value that the windows and doors need to achieve for the overall SAP calculation and overall u value to work and pass building regulations. We can tailor the products and glass spec we use to ensure our products comply.

As a general rule of thumb, thermally speaking, aluminium frame is the weak point of any door and the glass is the strong point. Therefore, sliding doors tend to be more thermally efficient than bi-fold doors, because bi-fold doors inevitably feature much more frame.

Moreover, sliding door profile is thicker and more bulky than bifold profile and wins thermally in this respect too.

For example, our Schuco ASS70 FD bifold door achieves 1.7 as standard and our Schuco ASS70 HI lift and slide doors achieve 1.4 as standard.


In sum, it does depend what you hold most dear. If you want to be able to fully open the doors to give the seamless transition from inside to outside, then go for bi-fold doors. If you want reduce the amount of frame and maximise glass sizes, making the most of the view, go for sliding doors. If you have strict thermal value requirements, you may need to opt for sliding doors.


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