The best frameless bifolding door is a serious alternative to the conventional framed bifolding door. However, finding the best frameless bifolding door also means understanding what frameless really means. But choose the right product and you are rewarded with a new bifold door that looks fantastic, is ultra-slim, very functional, safe, secure and weather resistant. And you benefit from much more glass and less visible aluminium frame.
In this article, we take a look at what is the best frameless bifolding door for external use only and what you should look out for and consider in your research.
Definition of the best frameless bifolding door
The fundamental difference between a best frameless bifolding door and a conventional bifolding door is how it looks, operates and is constructed.
Frameless bifolding doors, in short, comprise far less aluminium than a standard bifolding door – but are they truly frameless?
All bifolding doors need a frame, which is essential for the locking systems, track, sealing and security. Therefore there is no 100% frameless system. Unless you are hiding the door frames into the structure, you will always have some visible surround frame.
Then there are doors such as the Frameless Glass Curtains product (FGC), which is so well designed that it removes the aluminium profile on the vertical elements, leaving just glass and a view through the closed doors like no other product on the market.
There is no aluminium at the panel joints leaving just glass edges and advanced seals and gaskets. This doors is safe, secure, reliable, and weather-resistant.
Only structural glazing can feature no frame at all; many commercial buildings can feature structural glazing. So, while the use of the word ‘frameless’ may imply that there is no frame at all, there always will be some. Aluminium is required not only to provide strength and integrity to the product but also to provide a fixing point for the hardware and for the doors to hang and work correctly. Aluminium will also be used for the perimeter frame so that it can be fixed to the structure. The threshold will also be made of aluminium.
The best frameless bifolding doors have a design that aims to use as little visible aluminium as possible to provide more glass than a regular full-framed aluminium bifolding door.
What is a frameless door?
If we have, therefore, established that a best frameless bifolding door must still consist of some framing to critical areas, what constitutes a frameless door?
To a door or window professional, a ‘mullion’ is a specific window section or a combination of sections designed to create a vertical member or the appearance of one. In our opinion, a frameless door can be interpreted as one with no visible mullion. No mullion means no visible section on the intermediate verticals where all the doors meet.
The correct definition of a frameless door is one that has no mullion. No mullion should also mean no capping pieces, flat bars or any aluminium or plastic profile at the junction where the door panels meet.
This is our interpretation of what constitutes a best frameless bifolding door. Others may disagree with our definition. However, all three products we are comparing here (and others) market themselves as not having the door profiles found on conventional doors where they meet. With this in mind, we consider the definition a fair one.
Some bifolding doors are not frameless but marketed as such
Just about anyone researching a product will turn to the internet and most likely Google. However, a search for “frameless bifolding doors” will throw up a wide variety of results.
We carried out multiple searches for a variety of related search terms. Here’s what we found:
- Many companies are bidding for the keywords ‘frameless’ and ‘bifold’ to make you click on their website, but they do not offer this product at all. We checked.
- Study the images that accompany frameless doors and you will often see standard doors instead.
- Even national brands are advertising frameless doors, but they don’t offer them. We checked this too.
- Many advertised frameless doors are single glazed which are for internal use and don’t have weather certification.
- Doors marketed as frameless double-glazed doors have a profile where the doors meet in the middle – a visible ‘mullion’.
The takeaway here is that the word frameless has been adopted by those knowing no 100% frameless product exists, but are capturing your interest and clicks.
Three best frameless bifolding doors
When researching, it is easy to get confused by all the information. During our research on the internet, we found a lot of conflicting information regarding frameless doors; here is a selection of what we found:
- Some frameless doors are not really frameless
- Several products are only for internal or commercial use.
- Several brands that are frameless are only available single glazed
- Some frameless doors are the same products with a different brand name
Our goal was to find three best frameless folding doors suitable for residential use and that we could compare. These were:
- Frameless Glass Curtains Ltd of Chatham (FGC)
- ID Systems Vistaline
- Sunseeker Doors Frameless Double Glazed System.
What became evident in our research was that the frameless door description is overused and has different meanings for different companies.
Which is the best frameless bifolding door?
The three best frameless bifolding door products selected offer different visuals, technical specifications, price points and guarantees. The final choice you’ll make will be based on your specific criteria. While all products will meet minimum industry standards, some are better made and have more impressive features.
Frameless Glass Curtains, Sunseeker and ID Systems products are all popular and successful companies. The three products compared here are all beautiful doors and each company is well-established and has a successful track record in what they do.
Sunseeker has previously reported year-on-year growth, so their doors are clearly popular with customers. Frameless Glass Curtains designs its products from scratch and installs them nationwide and internationally. Their doors have recently been fitted in a world-class luxury cruise liner as well as terraced houses, mansions, eco homes and commercial. ID Systems also provides its products to many different dwellings, and they to have carried out some very impressive installations.
All the products differ; some are better specified and better certified. Our goal is to give you some balanced and impartial information to help you come to your conclusion.
1. Frameless Glass Curtains
The Frameless Slide and Fold Doors by FGC are an ultra-contemporary and expertly crafted solution for homeowners seeking a modern, unobstructed view. These doors are designed to eliminate the visible vertical mullion, providing a seamless and continuous glass look that no other bifolding or sliding door can match. This innovation offers full security and weather certification, making it the ideal choice for exterior patio doors.
One of the standout features of these doors is their patented glass edges, which replace the typical aluminium edges found on other doors marketed as frameless. This design allows for a fully transparent view, giving the appearance of continuous glass. The low 5mm weather-rated threshold and excellent U-values help lower energy bills, enhancing both functionality and energy efficiency.
FGC’s frameless slide-and- fold doors are engineered for tall door panels, accommodating sizes up to 1.3m wide and 3.0m high. This advanced design not only maximizes the view of your inside and outside spaces but also adds a dramatic architectural element to any home. The minimalist design offers a perfect alternative to conventional aluminium bifolding or sliding doors, with less aluminium, more light, and enhanced functionality.
These doors provide a superior aesthetic and functional experience. They are slimmer than even the thinnest sliding doors and stack more neatly than bifold doors, without encroaching on your space. The frameless design ensures larger glass panels and a spectacular view when closed, creating an insulated glass wall. When open, the doors offer enhanced ventilation and practicality with effortless operation.
Customisation options for these doors are extensive. They can be provided in any colour, with a range of standard RAL colours in stock for quicker delivery, including RAL 9003, RAL 9010, RAL 7015, RAL 7016, and RAL 9005.
Every frameless door by FGC is custom-built to precise dimensions and specifications, from 2 up to 10 or more panels, ensuring a brighter space and enhanced views of the outdoors. These doors are perfect for replacing dated patio doors or creating new extensions, offering a smooth transition between home and garden.
2. ID Systems Vistaline
The Vistaline slide-and-turn door system is a multi award-winning innovation, recognised for its quality, design, and performance by Real Homes and Build It magazines. Combining the narrow sight lines of sliding doors with the full opening capability of bifold doors, the Vistaline system offers the best of both worlds.
The Vistaline frames feature ultra-slim sight lines of just 45mm, less than half the width of typical bifold doors, maximising the view and significantly reducing intermediate frame widths. The system is uniquely designed and hand-made in the UK to Swiss standards, achieving low U-values from just 1.1W/m²K.
Innovative retractable weather seals in the track provide superior weather performance, ensuring effective sealing when the doors are closed. The system is available with double or triple glazing and offers options for inward or outward opening panels, each up to 1100mm wide and 2650mm high.
User-friendly by design, the Vistaline panels slide without encroaching on floor or patio space, turning and stacking beside the lead door. The doors can also be partially opened for ventilation. For security, the system features no external hinges, a ridge and groove connection between panels, and multipoint locking in the side jamb.
An advanced flush track with retractable weather seal technology maintains the system’s weather rating. The Vistaline system can be configured with up to 14 panels for openings as wide as 14m, with each panel sliding to stack at one end for an unobstructed opening. Precision-engineered for silent and effortless operation, the top-hung system ensures easy and smooth sliding and stacking of panels. High-quality components, including chromed steel mechanisms and running gear, ensure high performance and durability.
Customers appreciate the Vistaline system for its transformative effect on living spaces, seamless integration, and the professionalism of the installation teams. Positive feedback highlights the enhanced views, increased space usability, and high-quality finish.
3. SunSeeker Doors
The Ultra Slim Bifold Doors by SunSeeker are renowned for their innovative design and superior functionality. With over 5,000 installations in the UK, these doors have become a popular choice for homeowners seeking sleek and efficient patio door solutions. The Ultra Slim doors feature aluminium frames of less than 2cm, typically finished in anthracite grey, and utilise a slide and pivot system where each door panel opens individually, eliminating the need for folding hinges.
The Ultra Slim system is unrivalled in its slim sightlines, offering just 19mm of visible frame at the sides of each door. This means that a 6-door system has less obstructive frame than many 3-door systems from other manufacturers. Each door slides along guide rails and pivots to open, allowing for the widest possible access and stunning views.
SunSeeker’s Ultra Slim doors serve as a contemporary alternative to traditional slimline bifold doors. They look similar to bifolding doors when open or closed but operate differently. There is a main door that opens normally, while the other doors slide along guides and pivot open, stacking neatly at the side. Unlike traditional bifolding doors, these can be partially opened to allow airflow by sliding each door to the desired position along the guide.
The Ultra Slim Bifold Doors are available in a wide range of colours and are made to measure in the UK. They are space-saving, suitable for openings up to 10 metres wide, with all doors stacking to the side of the opening. The thermally broken aluminium frames and British Standard Kitemark K-glass included as standard ensure energy efficiency. These doors are also secure and PAS 24 certified, providing peace of mind. The quoted price includes site visit and installation, with prices starting at £1,495.
SunSeeker offers a range of customisation options for the Ultra Slim Bifold Doors. The aluminium frames can be powder-coated in up to 300 industry-standard RAL colours, ensuring high quality and durability. Glass options include laminated for security, argon-filled for insulation, antisun to reduce glare, obscured for privacy, and tinted for a modern look. Integral blinds are available in venetian or pleated styles, sealed within the double-glazed units for a dust-free environment and improved thermal efficiency.
The Ultra Slim slide and pivot system is more contemporary than traditional bifolds. The doors are fully retractable, stacking at right angles to the side of the opening, maximising the access space between the two areas. This system was made possible by a unique locking mechanism developed by SunSeeker, which ensures each door is secure without the need for bulky hinges.
Comparing frameless door features
In the following sections we take a look at the various features that make up a frameless door system and explain some of the key differences.
Door operation
All doors feature the slide, swing and fold arrangement that is typical of how these doors operate. The access leaf is swung open and then each panel slides along the track to its stop and hinges open. With all door panels open, they are stacked in a folded open position.
Glass options on frameless bifolding doors
If you are looking for an internal frameless glass door, it is fair to say any of these three products will be suitable.
If you are looking for an external door – a bifolding door, you will want a double or even a triple glazed door. As we suggested, some frameless systems are only available to buy single glazed when asked for as a frameless glass door. Do check this out when looking at these and other products on the market. A single glazed frameless door makes for an excellent room divider, pool enclosure or to separate off a garden. All three companies can provide this product in these circumstances.
Glass options separate and differentiate frameless glass doors
SunSeeker Doors offer their frameless doors as single-glazed only. If you want a double-glazed option, you’ll have to go with their Ultraslim variant but have a visible mullion.
ID Systems offer their Sliding Turn Systems but state clearly on their website that they are ideal for balconies, room dividers, and patio areas. However, they are clear that these doors only provide a ‘moderate’ weather rating for projects that do not require compliance with current Building Regulations. Therefore this rules them out for external use.
Therefore for glass options, the Frameless Glass Curtains product comes out on top. You can have single, double or even triple glazed in one product.
Frameless bifolding door aesthetics
Aesthetics is a personal matter. Everyone will have a different view as to which product is the better-looking door. Study the images of all three doors on the company websites and you’ll see some great installations set off by some beautiful doors.
Using our definition of no visible mullion, the Frameless Glass Curtains (FGC) is the clear winner. This is not to imply that the other doors are aesthetically inferior. The FGC product is the only one we know or could find with no visible mullion.
The FGC doors are designed and engineered to do away with the visible profile, no matter how small or slim, that the other doors used and require by design.
SunSeeker, ID Systems and other products all rely on some form of aluminium or plastic profile at the vertical areas where the doors meet; Â FGC uses sophisticated gaskets only. Â Again the result is no visible mullion.
FGC have achieved this through many ways, but one excellent detail is in the unique glass they use that is different from anyone else. Their doors use quality glass just like any other, but the spacer bar that separates the two panes is what’s unique. Where all other double-glazed products use a metal or plastic spacer bar, FGC’s is made of glass, and it’s toughened as well. FGC have also patented this toughened glass spacer bar and it is totally unique to them.
The edge of the glass detail looks sleek, continues the transparency of the glass right to the edge and looks completely different. Looking at the FGC doors close up reveals a really great design feature. We had never seen a double glazed unit with a glass spacer bar before, and we recommend you see it for yourselves.
Profile dimensions of frameless glass doors
All matters of visible mullions, spacer bars and aesthetics aside, we reaffirm that all three doors are attractive. For clarity, we provide some of the critical dimensions for each of the products.
The SunSeeker frameless system frame is 40mm high by 63mm thick. The Frameless Glass Curtains Clearline system is slightly different at 44mm x 61mm. Â The 4mm difference between the two is marginal and won’t affect the visual sight lines that significantly.
For the door panels themselves, Sunseeker doors are 42mm high and 51mm thick. The FGC Clearline doors are smaller than this making for a slimmer door.
The ID Systems doors also stack cleanly and neatly and offer similar dimensions to the above. Technical information wasn’t available to give you specifics. It really will depend on what product you decide to use from their range because of the single glazed issue highlighted above.
Folding panel dimensions
One advantage to having a frameless bifolding door is that it takes up far less space when all the panels are folded back. Full aluminium bifolds will usually take up far more space when all stacked together. This is because the doors are thicker front to back so it is logical that they will be bulkier too.
Taking a four-panel door as an example in the fully stacked open position, Frameless Glass Curtains (FGC) come out as the slimmest with only 180mm of stack taken up. Sunseeker doors are nearly twice as thick at 310mm. ID Systems are virtually the same as well.
Therefore if you are looking for the frameless door that will take up a small amount of space, FGC wins it. In our experience stacking thicknesses of doors are not the deciding factor for buyers – overall aesthetics tend to matter much more. However, you will want to consider this if you have doors inside your home as room dividers. The FGC doors are the slimmest of the three.
Threshold heights
As far as the thresholds are concerned, the door made by Frameless Glass Curtains has the competition beaten on the heights. Their doors offer an unbelievably slim threshold that sits only 5mm above the finished floor level. That aside, all systems can be set into the floor as low or high as desired to achieve a flat floor level inside and out.
Frameless door weather performance and security
We were unable to establish clearly whether the SunSeeker and ID Systems products have passed any weather or security standards. Â This does not imply they will be easy to break into or that they leak. Â If sales of standard doors and windows are anything to go by, consumers want to see some evidence of certification. On an ID Systems and Sunseeker door, it is quite hard to clarify. We’d welcome their confirmation on this.
Therefore if you are considering either the ID Systems or the SunSeeker frameless products in whatever variant, we would recommend you establish in writing what you are getting. With both being established businesses customers are buying their products, but we expected to see a more transparent approach to what their frameless products achieve technically.
FGC are very clear in what their doors offer. They meet the latest enhanced PAS security standards, severe weather rating and quality standards for their glass units.
Frameless bifolding door warranties and guarantees
Once again we recommend you check out each company to establish clearly what performance standards, certification and testing has been carried out.
With SunSeeker there was little by way of clear information either on their websites or when we contacted the Company.  Our understanding is that SunSeeker doors offer a 2-year guarantee on their products.
Frameless Glass Curtains offer a 10-year insurance backed guarantee.
ID Systems market a 5-year guarantee although we’d recommend establishing whether this is across their entire range, or product specific. Their warranties are also transferable should the property be sold during the warranty period.
Best frameless bifolding door conclusion
When compared to the SunSeeker and the ID Systems doors, Frameless Glass Curtains (FGC) are the better door. There are three key points that make this product different and worthy of consideration. Â These key points may not matter to every customer as each will have different requirements. Â However, for aesthetics, completeness and certification, FGC doors come out on top.
The lack of mullion
All three products are excellent, fit for purpose and sold by three different but established firms. For a frameless glass door without the visible mullion, the FGC door is better in our view. It doesn’t have one.
The complete door solution
The FGC door again seems to win on functionality with simplicity. One product does it all. It is a door that will meet every customer need as one product. If you want a double or triple glazed door you can have one without having to choose an alternative. FGC doors are suitable for both external and internal applications, commercial and residential projects as well.
Building Regulations and certification
As an external door, the FGC door meets Building Regulations. It also offers transparent information on its certification and accreditation. It’s security tested, weather tested and has patents. Vistaline also meets current Building Regulations. Sunseeker we are less sure about as their information is quite hard to come by. If you are interested in this product, they have to demonstrate to you that their products are compliant. Also, check with all suppliers how they deal with trickle vents, another essential part of new windows and doors.
The important thing to remember is that most types of frameless glass doors come with some compromise. You either have to choose a non-thermally broken system, or a slim system with advanced glazing or one that is for internal use.
Frameless Glass Curtains as a complete product doesn’t compromise, and we consider their doors be a great door solution whether you need it inside or out. It offers all the benefits of an insulated, secure, weather tested and certified aluminium door but as a frameless design without a visible mullion.
How much do frameless bifolding doors cost?
So what about the prices of these doors? The nature of the door industry is such that there are no recommended retail prices. All three businesses are transparent in their pricing, and we suggest you contact each company with your requirements for a quotation.
We have stressed throughout this review that each product is fit for purpose, and you should see all three to help your purchasing decision. We set some benchmarks to compare the three doors around the glass, as well as their aesthetics and technical specifications. We found a lot of confusion around the frameless door term, so we strongly suggest you do your research as well.
If you would like some personal advice about your project, please get in touch with us; we love talking about doors! Find out more about other frameless glass products.
