How to design open corner bifold doors

Thinking about open corner bifold doors for your new extension? Here is all you need to know and how to design open corner bifold doors correctly. We provide information about the doors themselves, the built opening, as well findind what brands offer some of the most impressive folding sliding doors, but in an open corner design.

Why you should consider open corner bifold doors

Assuming the extension budget stretches to the building work and the open corner bifold doors cost, open corner bifold doors deliver something special and unlike other patio doors on the market.

First of all, is the appeal of a two-sided glass corner with a minimal or invisible corner post. With the corner bifold doors closed, you get a visually striking feature in your room. Another benefit of a two sided glazed arrangement is the extra feeling of space and more light as a result.

Other pages In this section

Aluminium Bifold Doors

Even better with fixed or open corner bifold doors is how they transform a room fully open. The door sets slide and fold back, revealing a two sided clear opening, connecting your room to the patio area and garden. The room becomes larger and the entire space transforms on warmer days into a look entirely different from a regular open bifold or sliding door.

Of course, bifolding doors generally add value to a property. An open corner design arguably more so as it’s so distinctive and unique.

How do corner bifold doors work?

The design of the bifolding doors up to the corner is standard. You get the choice of standard or slim bifold sightlines at the door mullions and locking points. It’s only at the corner you’ll see a thicker frame detail with the square post. This post also acts as the main locking point for the door set.

Whilst the concept of a corner set of folding sliding doors is not new, traditionally there’s a brick or steel post at the corner. Product innovation has resulted in most bifolding door brands now having a moveable corner post. Open one set of doors, then the other and the entire post moves back with the one set fully opening the aperture with style.

The connected post fits on one door set. Every other operation in opening and closing the doors is the same. However, the corner post needs releasing and this is done by a flush bolt system, although it varies from product to product.

There’s even a removable corner post solution such as the frameless bifolding doors made by FGC. Their doors use a separate corner post design. It’s not structural, neither does it take the place of any essential supports.

The system works by connecting the corner post to one side of the corner.  One set folds as normal. The other set unlocks with the post and moves away too. All doors are now opened and including the corner post which has moved with the set of doors it is connected to.

Building a new extension for corner bifold doors explained

The construction of your extension will require a cantilevered arrangement on the roof to provide the necessary structural support to the building.  This need not be complicated.  With the right advice from your architect, builder or structural engineer, this is easily designed and constructed.

You’ll almost certainly need the services of a structural engineer. Their job is to carry out a full survey, understand your project brief and calculate the structural requirements for your builder or architect.

Whilst many competent builders have experience in this cantilevered design for a new roof, finding one with previous experience probably gives extra peace of mind. Your bifold door supplier and installer will invariably have worked with good builders on previous installations and may recommend some to you.

open corner white bifold doors in a new build home
Origin open corner bifolds replacing French doors

There are situations such as where new doors replace an existing set and these often won’t need any structural alterations. Many replacement door installations work fine with the existing lintels in place. Do always check with a suitable professional.

How the roof works with open corner bifold doors

Cantilevered steelwork engineered to hold the roof weight will need to be installed above the doors. This will also support the lateral weight of the door. Installing cantilevered steelwork around the aperture means that no supporting posts will be on display, so you can enjoy an uninterrupted view when the doors are open.

Choosing between external or internal corner bifold doors

Whether you choose the more popular exterior corner or internal corner bifold doors the construction of the doors is the same. The only difference is the manufacture of the doors and the direction of the corner.

The frame, track and any cill at the threshold is also cut to suit with neat and sealed joints, giving a professional finish with any quality bifold door product.

Understanding the corner posts available with corner bifold doors

When it comes to fixed or open corner bifold doors, there’s a choice of post designs. Not all are a truly open or invisible corner design, but all three provide different looks and price points.

open corner black bifold doors in a modern house
Bifolding doors with exterior invisible corner

The invisible corner post on corner bifold doors explained

Arguably the most striking part about open corner bifolding doors is the invisible corner post and where the roof appears to float. This is the invisible and full open corner design.

A fully open arrangement also costs the most as an overall project. However, it delivers the most impressive look, the best in minimal sightlines at the corner and looks stunning open and just as impressive with the doors closed. This design comes as a result of the correct building work, possible an architect and most certainly a structural engineer.

solarlux corner bifold doors in a glass room
Solarlux Ecoline bifolding doors with a static corner post and Solarlux Wintergarden glass extension

The static exterior corner post

A much simpler design is the fixed corner post from steel that’s slimmer or brickwork that’s slightly thicker. The bifold doors fix in the normal way to each side of the post. As a result, they’re just like regular bifolds and the cost is lower. However, fully open they create the same open aspect, albeit with a visible post.

open corner bifold doors
Solarlux bifold doors with static post and open corner

The static interior corner post

Here’s an alternative design giving a full open corner, but with a visible post set back inside the room. The advantage is reduced building costs as the post is supporting the roof, whilst at the same time giving a full open corner.

internal corner bifold doors in a kitchen extension
The invisible removable corner post on frameless bifolds by FGC

How to design your open corner bifold doors

You can have a flexible open corner that can consist from two to six or more leaves on the one side and one, two or more on the other; depending on the size of the structural opening and what is being constructed.  

The traffic door on a bifold provides extra functionality letting you open just one leaf for everyday access. It’s recommended for the improved usability and a good installer can advise further on the best positioning on one or both sets.

Then you have the usual substantial colour choice with your new open corner bifold doors as well as glass options, integral glass blinds, glass with extra security, sun-control and even acoustic glass.

It’s also worth bearing in mind all bifolding doors come as single or double doors using exactly the same profiles. Therefore, you get the option of matching doors elsewhere in the home or the extension.

Low, level and flush thresholds with corner bifold doors

Both internal corner bifold doors or external corner designs work just like standard bifolds giving you several options for a flush and level-access threshold. The considerations are all the same such as your builder understanding the track heights and building the structural opening to suit.

You’ll need to consider drainage and moving any water away from the bifolds in the usual way. There are numerous options for drainage with bifolding doors including contemporary solutions adding to the look of your bifolds at the threshold. Your builder, bifolds installer or architect can also advise.

How much do open corner bifold doors cost?

The significant cost of getting this bifold door design in your extension is actually the building work rather than the door cost itself. They do cost a little more but not significantly so.

Our research indicates an open corner design adds around £1000 to £1500 on top of the cost of two separate bifold sets and you may find this cost even less depending on the installer and the brand. Fitting costs vary across all businesses. Therefore, always get at least three or four quotations and ensure you’re comparing like for like.

Of course, some bifolding door brands cost more regardless of the design. Schuco, Reynaers, Solarlux, Vistaline, Sunflex, Centor are at the better end of the market. Aluk, Smart Systems or Origin will probably work out cheaper.

How to choose the best brands of open corner bifold doors

Most of today’s products come with an open, fixed or internal corner bifold doors design. The information you need to choose the best bifold remains the same. This article features high-end bifolding doors in open corner designs by Sunflex, Solarlux and FGC.

Above all, quality manufacturing, a well-built structure and professional installation are key to a successful outcome.

YouTube video

Providing expert help to homeowners and trade professionals since 2010




Get Free help finding the right products from the best suppliers

16:42 30 Oct 23
Nick responded incredibly quickly to my enquiry (on a Saturday too!), and was able to offer invaluable advice on both aluminum systems and manufacturer / suppliers. Thanks Nick!
chris steerchris steer
16:18 09 Oct 23
Had a meeting with Nick during the grand designs show. Was extremely helpful and professional would highly recommend
Chris WesthorpChris Westhorp
19:55 13 Sep 23
Extremely helpful with pointing us in the right direction to find the products we required and suggesting firms that could reliably fit them.Nick was quick to reply and very detailed in his advice.Highly recommend reaching out to them.
Cathy GreenwoodCathy Greenwood
07:03 11 Sep 23
Update - A second email to nick for help on bifolds resulted in a detailed informative reply even on a Sunday ! This guy is so knowledgable and helpful .I approached Nick for an independent view on sliding doors v bifold and the different brand options . His reply was extremely detailed and prompt and allowed me to navigate this often confusing world in a much more informed way . Thanks so much Nick
Anthony CraigAnthony Craig
12:45 05 Sep 23
This is a must site for anyone looking for advice. Great service and very quick answers to questions. Nick has been of great help quiding us through the maze of aluminium products. Thank you
Philip DuffieldPhilip Duffield
20:24 26 Jul 23
I contacted Nick @ ATS for guidance on what aluminium sliding door systems would be suitable for an opening in an extension that is going to be both wide and tall. He came back really quickly with very detailed and incredibly helpful advice. He is clearly extremely knowledgeable about the systems on the market and their respective features and capabilities. If you’re feeling a bit lost by the overwhelming range of choices out there, I’d definitely recommend contacting him.
Dariush HekmatDariush Hekmat
17:25 19 Jul 23
Nick's advice is great. He is always quick to respond and spends time on responses, which really help to make an informed decision.
Alan FosterAlan Foster
07:51 12 Jul 23
Absolutely fantastic. Asked for advice about replacing Crittall (?) windows late last night and early this morning received 3 great suggestions and contact information for suppliers
Rachel LauRachel Lau
09:24 16 Jun 23
Fantastic website full of valuable and pragmatic advice about product selection and comparison: no other website gives information like this. Truly written for public interest. Don't hesistate to reach out to Nick via the mailing system. He responds very quickly, is friendly, and has very sound and high knowledgable advice. I have already shared this with my friend planning her own grand design.
guard Charlieguard Charlie
12:28 14 May 23
I emailed this company just on the off chance they could help me with new magnetic sliders for my patio door. They were not able to supply those but were so very helpful providing me with the name of a company who could. I am so very grateful at the great service. Dare say customers must be very happy. thank you so much.
Benjamin LewisBenjamin Lewis
10:06 04 May 23
Nick is very helpful indeed. Extremely knowledgeable on bifolds which was in relation to my query. Great website as well, some very useful articles. Particularly appreciated the article that lists all the major bifold options in order of their sightlines! Thank you!
P JonesP Jones
08:07 15 Apr 23
I asked Nick some questions about an installation we were considering and he replied within hours with some very useful suggestions that will probably lead us to using a different make and supplier. Thanks, Nick. Great work.
Nicholas WallNicholas Wall
13:18 02 Apr 23
Looking for fair and honest expert advice on all aspect of aluminium windows and doors? These guys will arm you with all the information you need to make the RIGHT choice in a highly complex, crowded marketplace. post a question and you will get a very quick professional answer you can rely on being based on fact. Thanks guys!
Giorgia SiriacoGiorgia Siriaco
16:25 21 Mar 23
After a lot of research to find doors that would meet our unusual size requirements and feeling increasingly uncertain about the best way to spend our small budget, I stumbled on the ATS website, and I'm so glad I did! I contacted ATS to request advice and Nick promptly replied with a wealth of information, providing us with options and relevant contact details. I only wish I'd found them sooner!
Carol NortonCarol Norton
10:01 17 Mar 23
I've been so confused about how to achieve the look I'm after, and going round in circles with various window/door companies, trying to get away from the huge chunks of plastic currently around my windows. I didn't expect an email to a company found through a Google search to really help - but I was desperate, so I tried. I'm SO glad I did. Finally I have clear explanations from ATS of where I've been going wrong, exactly what I'm looking for, and a list of local companies that might be able to provide it! The response has excelled my expectations and I feel as if I'm finally inching closer to a home with which I'll be happy and comfortable: thank you.
David NunnDavid Nunn
20:54 14 Mar 23
It is rare that I write reviews, however after my very positive communication with Nick - enquiring about suitable slim sash aluminium windows for my project, I felt that a review was definitely warranted. I can reinforce the many positive reviews posted so far, Nick was very quick to respond, providing comprehensive detail, with excellent independent advice.In summary, great service, thank you Nick.
Chantal AuerbachChantal Auerbach
13:04 09 Mar 23
Nick from Aluminium Trade Supply was incredibly helpful informative and pleasant to deal with. He responded quickly to emails and was very knowledgeable. Highly recommend being in touch with Nick if you are considering new aluminium windows or doors.
Lee JonesLee Jones
20:21 22 Feb 23
I dropped Nick at Aluminium Trade Supply an email re high security slim sightline bi-folds and their alternatives and he responded that quickly (and so comprehensively) that I felt bad I’d not paid him for his time!Nick Sir your product knowledge is outstanding and you are providing a level of service that goes wayyyy above and beyond expectations. I’ll definitely make sure I mention Aluminium Trade Supply to anyone I encounter looking for a fenestration solution 🙏🏼
15:13 13 Feb 23
We are looking to replace some old UPVC patios doors with aluminium ones. The ATS website is a great source of advice in an area where clear information is sorely lacking. Having used the website, I then followed this up with a number of specific questions relating to our search, and Nick came back very quickly with clear, detailed and very useful advice.I have been very impressed with both the website and with Nick's advice. My only regret is that I didn't come across ATS before replacing various windows in 2021 - I'm sure it would have saved me a lot of grief and money! Thanks again Nick.
Azza McCabeAzza McCabe
17:47 01 Feb 23
So impressed with this company.Responded to my query quickly andgave valuable advice. Nick was extremely helpful and we were able to move forward with our project.
Adri LoloçiAdri Loloçi
11:21 08 Jan 23
Nick was super fast to respond and provided some great recommendations. I would recommend this website to anyone looking to find bifold or sliding aluminium doors.
Stephen HoustonStephen Houston
16:16 03 Jan 23
Looking for aluminium crittall style internal door and external patio French doors. Noted good reviews and thought would ask for advice. Comprehensive reply with excellent independent advice and lists of fitters who could provide products and installation. Great service.
Inga GeachInga Geach
08:25 21 Dec 22
Nick from Aluminium Trade Supply has been extremely helpful with navigating the jungle that is aluminium glazing for our upcoming extension project. His advice was prompt, detailed and always impartial. Very grateful for your input, thanks Nick!
Amanda BurtonAmanda Burton
10:54 16 Dec 22
Brilliant website and an excellent service. Nick provided not only detailed advice and supplier contacts, but highlighted the considerations of various products so I could make an informed choice. Our Sunvista minimal sliders were fitted this week and I couldn't be happier, stunning. Thanks once again for your advice and recommendations, invaluable!
Keith BarnesKeith Barnes
17:18 10 Dec 22
Very helpful advice given to my question, including the name of 3 different companies that i could try for the product being enquired about. Many thanks
Munim ChowdhuryMunim Chowdhury
11:45 13 Sep 22
Nick has been very helpful on signposting me to a number of partner organisations for steel/aluminium doors.
SUSAN wallaceSUSAN wallace
17:26 31 Aug 22
My experience with this firm was exceptionally good and this is notalways the case as a female, dipping a toe into technical waters.I was spoken too with courtesy and at a level that helped me consolidate what was needed .On top of that I was given a list of companies and places where I could obtain the type of product I needed.I could not thank them enough and would certainly go there again and reccommend others do too.
Paul SalterPaul Salter
22:39 22 Aug 22
Contacting Aluminium Trade Supply is like contacting the Oracle direct. Advice is always comprehensive and balanced. On multiple occasions they have provided me with options that fully meet our objectives. Many thanks.
Nick McCormackNick McCormack
20:25 14 Aug 22
Really helpful and useful came back to me on a Sunday with some invaluable information. Highly recommended.
ray addisonray addison
13:14 14 Aug 22
received a prompt reply to my query,and helpful information from ATS