What to consider when specifying bi-folding doors Part 2

Sieger Systems offer completely bespoke aluminium glazing systems that are fabricated for the specific openings they are desired for and in the finish chosen to suit the architectural design. With bifolding doors from Sieger, it isn’t the case that you can measure the openings, come and visit us and expect to take home your bifolding doors on that day. Due to the bespoke nature of our glazing systems we will create the CAD designs of the system which shows the exact glazing specification, size, ironmongery and frame finishes to then fabricate the system. During the design stage we will visit the site to conduct a site survey which will provide our Sieger fabrication facility with the precise measurements for the systems.

Prior to specifying bifolding doors on your architectural project there are a few things to consider. To help with this process, we have put together some key points to keep in mind and some frequently asked questions.


How much do Sieger bifold doors cost?

Bifolding doors from Sieger vary in price as they are manufactured bespoke to each project and therefore the glazing specification and configuration differ from project to project. However, we are able to provide approximate costs for the Sieger bifolding door systems, they are the following:

Sieger 120 Bifold Door | £750 per m2*

Sieger Lux Bifold Door | £1,000 per m2*

Sieger Super Lux Bifold Door | £1,250 per m2*

*All systems from Sieger are manufactured bespoke for each project to meet the exact measurements required for each project, therefore prices will vary from project to project.


What are the differences between these bifolding doors?

There are two main differences between the aluminium bifolding doors from Sieger, these include the sightlines between each pane and also the maximum sizes of the bifolding doors.

With Sieger bifolds the mantra of ‘one size fits all’ just doesn’t apply. Each bifold is manufactured bespoke to each opening, therefore the opening determines the size of the bifolding doors. However, if you are designing a new build and want a size to maximise focus on the glazing, then knowing maximum sizes is advantageous.



Sieger boast the tallest bifolding doors on the market, measuring a maximum height of 5 metres. These 5m tall bifolds are a unique design that allows architects and specifiers to create impressive elevations of bifolding glass.


The maximum sizes for the Sieger bifolding doors are as follows:

Sieger 120 Bifold Door | 1200mm wide x 3000mm tall*

Sieger Lux Bifold Door | 1200mm wide x 3000mm tall*

Sieger Super Lux Bifold Door | 1200mm wide x 5000mm tall*

*Per pane


Each Sieger bifolding door offers different size sightlines, some slimmer that others but at different price points. Modern architectural glazing developments are seeing sightlines becoming slimmer and slimmer to create beautifully elegant and contemporary systems.


The sightlines of each Sieger bifolding door is different:

Sieger 120 Bifold Door | 120mm

Sieger Lux Bifold Door | 74mm

Sieger Super Lux Bifold Door | 144mm



Can glazing bars be included within a bifolding door design?

For architectural designs that are looking to create an industrial style aesthetic, the Sieger bifolding doors can be manufactured with additional glazing bars to create this design. These glazing bars are either true or applied glazing bars with dummy spacer bars to give the appearance of traditional art deco style glazing.


Do architects prefer siding doors or bifolding doors?

There are pros and cons to both systems and it really comes down to personal preference and the desired aesthetic achieved by the glazing and the opening. Generally, architects prefer sliding doors due to the slim sightlines achievable with sliding door systems however it really depends on the project.

Bifolding doors are recommended on projects that have small openings because bifold doors will maximise the use of this space as the panes stack neatly to one side of the opening to reveal a completely open aperture. Whereas, if sliding doors were installed within small openings, they would take up a large portion of the opening which would restrict the connection to the outdoors.

Most modern sliding doors have minimal framing, resulting in a ‘more glass, less frame’ design which is more desirable among contemporary architecture. Many architects tend to go for sliding doors over bifolds as there’s too much frame with bifolding doors, but actually bifolding doors can be relatively slim framed with a large glass to frame ratio. The large widths that the bifolding door panes can be manufactured to creates a large expanse of glass per pane.

Can any building have opening corner bifolds?

This depends on the opening and Sieger always ask to review the opening beforehand. The steel/ supports and the corner configuration need to be to be assessed before we confirm that the corner opening design is possible.

One of the main issues with corner opening bifolds is the need to calculate whether the system needs to be inward or outward opening. There are restrictions as to whether corner opening bifolds are inward or outward opening. Convex corners have to open outwards while concave corners have to open inwards.


Is there a recommended number of panes for bifolding doors?

There isn’t a recommended number of bifolding panes, but Sieger advise that the bifolding doors are designed in odd numbers to allow for a traffic door (also known as a pass door) which provides quick access to the outdoors without having to open the whole set of bifolds.

It is possible to have a traffic door with even number bifolds, but with this design the traffic does has to open the opposite way to the bifolding panes which results in a thicker profile where the pass door meets the bifolds.

To maintain a slim aesthetic Sieger advise that the bifolds are designed in odd numbers if a traffic door is desired within the configuration.


Should I have a traffic door in my bifolding doors?

It’s not a necessity to have a traffic door within a bifolding door configuration but they are very useful when it comes to providing easy access outdoors. A traffic door within a bifolding door arrangement can be treated like a single casement door which blends in with the configuration of the full bifolding door system.


If you are unsure which bifold door is best for your project check out our technical advice article on the best bifolding doors.


To get in touch with us about our bifold doors or if you have any questions, simply email [email protected]

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