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Award winning thermally broken bifold doors - available with double or triple glazing

The award winning SUNFLEX SF55 thermally broken aluminium bifold doors have been developed to shape the future of the folding door market. Not only does it provide a compact profile depth of only 55mm, in addition to narrower sightlines maximising glass area. It boasts of an unrivalled 24mm patented shaped polyamide thermal break, making the SF55 the slimmest, most thermally efficient, secure and reliable bifold system available.

Key features

  • Award-winning - named Build It magazine's 'Best Glazed Doors'.
  • Revolutionary narrow sight lines (115mm) maximising light and enhancing your view.
  • Slim front to back profile (55mm) minimising stacking area.
  • Triple gasket for finger cushioning and tight compression seals. The most weather tight bifold doors available.
  • Severely weather rated with weathered track and unbeatable reassuring test results (900Pa water tightness).
  • Extremely versatile, up to 1,100mm wide panels, 3,500mm high, open in/out flush or weathered track option.
  • Mushroom locking into side jamb coupled with top and bottom metal shoot bolt rods, excellent security. WK2 security package available.
  • Integrated ventilation option with a full height tilt and turn window within the bifold doors.
  • Secured by Design award. Designed and installed to police preferred specification.

Flexibility in design

The system may be folded to the left or the right, open to the inside or outside. It can have panels all folding the same way or split with a number folding to each side.

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Whatever your requirements our bespoke range of bifolding doors can provide the solution. All systems can open either to the inside or the outside with panels opening to the left or the right. With all bifolding door systems an odd configuration will provide a single access door, which can stack the same direction or to the opposite side.

In bifold situations two panels will easily open together allowing access between spaces. Once fully open panels will stack neatly at 90o, all to one side or split with a number of panels to the left and right. With our unique stacking catch the doors will then hold themselves open meaning doors will not start to close if there is any breeze.

Our systems are also available with fixed or moveable 90o or 135o angled corner posts making it possible to completely open up corners, bays or even segmented radius curves.


Standard aluminium finishes

As standard we offer the choice of the six colours -Silver Anodised EV1,Traffic White RAL 9016 semi-gloss, White Aluminium RAL 9006 semi-gloss, Grey Aluminium RAL 9007 semi-gloss, Anthracite Grey RAL 7016 semi-gloss, Graphite Black RAL 9011 matt or Slate Grey RAL 7015 matt

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These colours offer our shortest lead times and are included within our quotations. Once we have prepared a quotation we are able to send colour samples for approval prior to progressing with your order.


Special RAL colours

Over our standard range we are also able to offer the full RAL classic colour range. The range consists of over 200 colours which come in a matt, semi-gloss or full-gloss finish. The colours shown in the swatch will give an indication to the colour shade, however before progressing with an order we can provide aluminium samples for your approval.

RAL colours for the SF55 bi-folding door by IDSystems



RAL swatches for the SF55 bi-folding door by IDSystems

RAL swatches

RAL classic colour swatches can be purchased directly from us for £10.99 (including postage).

The full colour swatch is a great tool to allow you to choose the colour of your doors and windows to complement your internal decoration, external render, brickwork or other features within your project.

To order a RAL swatch you can make a card payment over the phone by calling us on 01603 408804. If you have narrowed down your choice we are able to send a colour sample for your approval when placing an order.

Glass options

As standard all of our products will be fitted with glazing that exceeds Building Regulations Document N and L which govern safety and thermal efficiency. Over our standard glass there are many options for you to choose from including:

  • Laminated glass: Improved security and UV reduction preventing furniture fading.
  • Tinted anti-sun glass: Reducing solar gain, available in blue, green, grey or bronze.
  • Neutral anti-sun glass: Neutral in colour with reflective properties to reduce solar gain.
  • Self-cleaning glass: Reduces the need to clean the glass, very useful in roofs.
  • Obscure glass: Our satin deco is a stylish solution for areas requiring privacy.
  • Low-iron glass: Improves the light transmittance through glass while providing some free energy. 



Download | Aluminium Bifold Door brochure


IDSystems - Versatility
IDSystems - Product guarantee - 10 years
IDSystems - Unique finger safe gasket technology
IDSystems - High security locking
IDSystems - Thermally efficient lowest U-Values
IDSystems - Effortless operating system
IDSystems - Flush or weathered track
IDSystems - Integral venetian blinds
Award winning products


The manufacturer recommends panel widths do not exceed 1,100mm and a maximum height of up to 3,500mm.


The SUNFLEX SF55 bifold door profile is constructed from a strong aluminium extrusion. This has been thermally broken by a 24mm polyamide insulation bar, guaranteeing it optimum resistance to combat heat loss and condensation. The minimal framework is offered as square edge profile.

Track options

There are three choices of track; a standard weathered track for a severe weather rated system, a flush track recessed into the floor, and a low threshold track that sits between the two. The flush track complies with Building Regulations Document M for disabled access and is without guarantee against wind and water penetration.

Weathered track

In any exposed location we would always recommend the use of a weathered track. When used with an outward opening door a weathered track can be fully recessed below your internal floor level meaning that there is no threshold to trip over, just a 35mm step down to the outside. An external deck or paving can be brought up to the track on the outside giving a very minimal difference in levels whilst maintaining a weather tight seal.

Flush track

The flush track option is recessed into the floor, providing an uninterrupted floor finish. Between the door and the flush track are double, twin nylon brush piles incorporating a fin seal, which close the gap effectively. It is recommended that some form of drainage and a slope away from the doors are integrated.

Low threshold track

Sitting between the two above options the low threshold track can be recessed into the floor with matching inside and outside floor levels and just a small 14mm upstand on the track. The upstand allows the doors to form a seal, creating a weather performance superior to flush track.

Download track options (Adobe PDF file - 2.21MB)


PAS 24 compliant - meets requirements of Approved Document Q of The Building Regulations 2010 (Security - Dwellings)
Secured by Design award -
Police Preferred Specification

Lead door or single pass door fitted as standard with a five-lever key-locking cylinder, incorporating mushroom headed ESPAG bolt and shootbolts top and bottom. A central latch position can be added for convenience with a horizontal lever handle. First opening pair in even number configurations consist of a two-point top and bottom shootbolt mechanism.

For improved security, all SUNFLEX bifold door systems are internally glazed as standard, with centre secured locking hinge pins and interlocking gaskets.

Where there are an odd number of panels, a five-lever profile cylinder is fitted to the end lead door or to the first opening pair in an even number of panels. It can be fitted to either the inside only or both internally and externally, meeting the requirements of the Association of British Insurers.

The shootbolt rods are manufactured in aluminium and linked by a corrosion resistant cam. In addition they are capped with polyamide cones that prevent any damage to the track when locking, whilst compressing the panels tight against the top and bottom seals.

Throughout the range of SUNFLEX bifold door systems you have the option of internal and/or external handles. Handles are fitted to every intermediate door panel and additional locks can be added at these points for higher security.

There are further enhanced security options available and panic locks can be fitted for fire escapes, etc. Sunflex also offers electric latch-release locks and a rollerball latch lock for commercial use.

Weather seals

The system is a severe weather rated system when used with the weathered track option, providing a top and bottom double-rebated seal. Unique triple gaskets provide a finger cushion and eliminate draughts. The system BS EN 12207 air permeability Class 4, water tightness Class 9A (900Pa), wind resistance Class 4.

The triple gasket seals both at the front and the back of the panel are continuous, even behind the hinges, and of superior quality (consisting of long lasting EPDM). The unique design of these triple self-sealing gaskets provides a minimal sightline. Whilst providing a cushion to minimise injury if fingers were to be trapped, in addition to improved weather performance.

Operating system

The stainless steel running mechanism consists of four wheels, manufactured from tough glass fibre reinforced polyamide. And set around a maintenance-free sealed ball-bearing, giving a quiet, smooth operation with optimum resistance to extreme weather and temperatures fluctuations.

The SUNFLEX SF55 bifold door can be adjusted to alter height and load of the system to provide a degree of tolerance. The wheels of the running mechanism run in a channel in the sides of the track rather than sitting directly on the bottom. Unlike many inferior systems, this minimises the risk of the operating system fouling, should any dirt or debris be allowed to build up in the bottom of the track.

The unique design of running gear mechanism hinged between the door panels eliminates the need for a sliding post. This achieves smoother operation, slim sightlines and larger glass area.


The SUNFLEX SF55 system is available as standard in silver anodised EV1 or polyester powder coated to a semi-gloss finish - white RAL 9016; aluminium RAL 9006; grey aluminium RAL 9007; or anthracite grey RAL 7016.

Single doors fitted as standard with lever handles. With first opening pair and intermediate door panels fitted with flush handles are specially designed to complement the door system. Standard colours are white RAL 9016; black RAL 9011; aluminium RAL 9006; grey aluminium RAL 9007; or anthracite grey RAL 7016. Gaskets are in black, with hinges mounted within seal sightline available in white RAL 9016 or black RAL 9011.

Other RAL colours are available with over 200 colours to choose from. You can even have different colours to the inside and outside (dual colour) or different wood grain effects are available for a nominal charge. The RAL colours can be applied to the handles and hinges if required or alternatively there is a stainless steel handle and hinge option. In addition you can specify whether a matt, semi-gloss or full-gloss level of paint finish is required.

A marine environment finish, required to all systems within 5,000m of a shoreline or chemical swimming pool environment, is also available.


Integrated ventilation option with a full height tilt and turn window within the bifold doors. This enables significant ventilation without having to open the doors and also offers an additional exit point at the opposite end from where the doors open.

Trickle vents with an airflow equivalent to 2,500mm2 or 5,000mm2 can also be incorporated with the addition of a 35mm add-on head profile. These will be colour coded to suit the frame colour choice.

Panel catch

In the situation of a single access or pass door in an odd number configuration, the panel is fitted with a panel catch. This prevents the door from swinging back around in high winds, and also counter weights the door with the adjacent panel for effortless operation.

Pull handles

When the bifolding door system opens externally the intermediate panels are fitted with a moulded 'D' shaped handle. This is attached to the internal hinge between two even panels, and sits neatly within the gasket line. This enables easy closure of panels against the compression top and bottom gasket seal.


The SF55 bifolding door system is internally glazed and can accommodate glazing ranging from 4mm clear toughened glass up to a triple glazed sealed unit of up to 36mm.

Our standard 28mm unit comprises of 4mm clear toughened glass with Low-E (low emissivity) to the inner pane x 20mm argon gas cavity x 4mm clear toughened glass. This complies with the Building Regulations for safety and thermal efficiency.

All units are BS kite marked, manufactured to BS EN 12600 and BS 5713:1979 standards.

IDSystems offer a wide choice of glazing options. Including, manual or electrical internal venetian or pleated blinds which can be incorporated inside the glazed unit. These are very popular, especially on internally opening systems where curtains are not practical.

U-Values and heat losses

A U-Value is a calculation of the amount of heat lost through a building material. The calculation of U-Values can be quite complex as it is measured as the amount of heat loss through a 1m2 of material for every degree difference in temperature either side of the material. It is indicated in units of watts per square metre per degree Kelvin or W/m2K. The simplest way to approach U-Values is the lower the U-Value the more thermally efficient a product is.

A U-Value of a door or window is calculated by working out by determining the U-Value of the frame and the area of the glass and is then quoted as an overall U-Value. Beware that some manufacturers may just be providing the U-Value of the glass alone which gives a false overall value. All of our systems have been thermally simulated in accordance with CE standards to BS EN ISO 10077.

Building Regulations approval will be required on all extensions and new builds to which we are able to provide CE data showing compliance. Any replacement works we are able to cover being a member of FENSA and a certificate would be provided on completion of our installation.

Double or triple glazing

Double glazing is a minimum requirement for external doors and windows. Our standard double glazed units consist of a soft-coat Low-E (low emissivity) pane and an argon gas filled cavity which provides a centre pane U-Value of 1.2W/m2K. Over the standard we can provide super insulated double glazed units providing a centre pane U-Value of 1.0W/m2K whilst providing solar control.

Triple glazing is becoming increasingly popular, especially in total new builds, as it provides the lowest U-Values possible and can be up to 40% more efficient than double glazing. Combining two panes of Low-E glass and two gas filled cavities glazing U-Values as low as 0.5W/m2K are possible with the added benefit of great sound reduction.

For more information on our huge range of glazing options or for help in specifying the correct glass for your project contact our technical sales department on 01603 408804.

Solar control and the benefits of solar gain

With the standard glass specification retaining as much heat as possible you may wish to consider reducing the heat transfer from outside which is known as solar gain. Solar gain can make glass roofs, conservatories or south facing elevations quite uncomfortable in the height of summer months.

A solar control glass is a glass with a either a special coating or a body tint to reduce the amount of heat entering a building either by reflecting or absorbing heat. Using a solar control glass can reduce the need for air conditioning and blinds. Whilst the solar control glasses are great at reducing the heat they will also reduce light transmittance.

Building control often recognise the benefits of solar gain in modern buildings as large areas of glass will work as a source of free energy during cooler months and increased solar gains are recommended. The use of low-iron glass can increase the heat and light transmittance to provide further solar gains during the autumn and winter months. Many modern designs incorporate overhangs to cast shadows over glazing during the summer combatting the solar gains. Thus allowing solar gains as the sun gets lower in the sky later in the year reducing the need for heating.

Safety glass

When required we fit toughened glass to comply with Building Regulations Document N as an alternate method of compliance we are able to fit laminated glass. Both options have their pros and cons.

Toughened glass

Toughened glass has been heat tempered to increasing its strength over ordinary annealed glass by up to five times. Other than the strength the advantage of toughened glass is that should it break it would shatter into non-sharp pieces. It is also available with the widest variety of coatings and can be supplied in larger sheets than equivalent thickness laminated glass. 

When the glass is toughened it can suffer from some visual distortion making, meaning the face of the glass is not perfectly flat distorting some reflections. 

Laminated glass

Laminated glass is manufactured by bonding two panes of annealed glass with a clear plastic interlayer. The benefit of laminated glass is that if it’s broken the glass will crack rather than shattering, improving security. In addition, laminated glass reduces bleaching of carpets, curtains and furniture by filtering UV rays that would usually penetrate the glass. 

The drawback of laminated glass is that extreme heat or cold can cause invisible defects in the glass to form a crack due to the two panes expanding and contracting independently. As the laminated glass is not toughened is does not suffer from the visual distortion that can occur to toughened glass during the toughening process.

Custom designs

As well as offering full height clear glass we can also provide a more traditional style of glazing by incorporating glazing bars, Georgian grids or lead work. Please contact us for further information.

Cat flaps

Often neglected when planning your new build or extension is where a suitable space may be for your feline friend, we have the ideal solution. It is possible to have a cat flap fitted into a glazed panel by cutting a circular hole into the toughened glass unit for you to fit an in-glazed cat flap.

Venetian blinds

We are able to fit venetian blinds within the glazed unit, ensuring a totally dust-free environment which requires no cleaning or maintenance. These are very popular, especially on internally opening systems where curtains are not practical.

Integrated blinds can be tilted to help prevent the build-up of excessive heat and glare of the sun during the daytime and provide privacy when closed. Blind units can be manually operated with an ingenious magnetic control device or electronically operated via remote control. Please visit our dedicated blinds pages for further information.

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