Aluminium - SF55i

Aluminium bifold doors - SF55i

BSI Kitemark | 643635PAS 24: 2016 certifiedSecured by Design logo

For more than thirty years SUNFLEX has lead the way in the design and manufacture of industry-leading door systems. The SF55i aluminium bi-fold doors are the new entry level addition to the range, providing a top of the range specification for a mid-range price whilst sharing almost all of its unique key features, innovations and design characteristics of the award-winning SF55s system.

The advanced German design and engineering, slim sight lines and contemporary square edged profiles ensure that the SUNFLEX bifold door range are not only the most advanced systems available on the market, but that they look and perform perfectly time after time, year after year.


  • The SUNFLEX SF55i is an innovative version of the award-winning SF55s aluminium bifold door.
  • Manufactured from the same square edged aluminium profile as the SF55s, measuring just 55mm from front to back.
  • Designed with alternate gasket and hinges compared to SF55s system
  • Accommodates a glazing unit of 28mm, 30mm or 36mm.

Maximise your opening with panel widths up to 1200mm and 3000mm maximum panel height without the need for a sliding post.

Aluminium is an ideal material as it’s light, strong and stable with slim profile sections to minimise the visible framework and maximise the glass area.

Double glazed U-value for overall frame and glass from 1.6W/m2K.
Triple glazed U-value for overall frame and glass from 1.2W/m2K.

Acoustic performance tested at Rw=36dB. Further upgrades available.


Choice of 3 thresholds

Weathered track with double rebates offering peace of mind even in the most exposed of locations. One of the only bifold doors that can offer a double rebates on the bottom track which is why we achieve enviable weather test results ensuring that the outside is kept outside. On outward opening doors the internal finished floor can be level with the top of the track and then the step down to the outside can be as small as 3cm.

Low level track with single rebate low level Doc M compliant track recessed in to the floor with a single rebate. The floor on the inside and outside can be at the same level with the track in the middle sloping up only 14mm. This provides a single rebate for the doors to close tight against which is more weather tight than the flush track.

Non weathered flush track, Doc M compliant track recessed in to the floor with no rebates. Using a twin brush pile and a nylon strip for a virtually seamless connection between inside and outside. Whilst this is a very subtle detail it is recommended for a sheltered area only as there is not a continuous seal and reduces the weather rating with no guarantee against wind and water ingress which is a compromise for this contemporary look. A slope away or drainage channel is then recommended on the outside to prevent any water ever pooling up against this track.

The SF55i includes the following features and benefits

  • Incredibly slim frame gives a narrow sightline of just 117mm when the doors are closed, maximising your view and the light in to your home.
  • Manufactured from square-edged profile giving a much sought after contemporary style, perfectly complementing the SUNFLEX UK range of windows and glass roofs.
  • Handles are colour coded as standard and designed to finished in-line with the door frame offering and uninterrupted view through the glass. A horizontal lever handle with a latch can be requested for a more traditional operation.
  • The system frame is assembled using patented moulded internal corner blocks and finished with mitred corners to maximise system strength and rigidity compared to cheaper butt jointed alternative systems.
  • Independently tested, sharing the same manufacturing standards as the industry leading SUNFLEX SF55s & SF75 systems.
  • Severely weather rated with our standard weathered track.
  • 300Pa water tightness (Class 7A | BS EN 12208 standard) and 600Pa air permeability (Class 4 | BS EN 12207 standard)
  • Resistance to wind load 1,200Pa (Class A3) to BS EN 12210 standard
  • Advanced multipoint lock, comprising of a combination of side locking on lead door panel with hidden top and bottom shoot bolt locking on remaining panels.
  • Exceeds the requirements of PAS 24:2016, the security test for Building Regulations approved Document Q.
  • Carries the prestigious BSI Kitemark™ certification for quality.
  • Awarded Secured by Design accreditation, meeting a police preferred specification for security.
  • Unique to SUNFLEX bifold door systems the top and bottom shoot bolt locks can be doubled with our twin lock upgraded. This upgrade enables the locking system of one panel to be internally linked to the adjacent panel, providing four locking bolts rather than two.
  • Thin 8mm gasket between panels preventing anything substantial from being used to attempt to lever the doors open.
  • Hinge pins secured by internal grub screws ensure that the panels cannot be separated.
  • Five-lever Euro profile lock cylinder complies with requirements of British Insurance Standards and BS3621.
  • Option to have no key lock to the outside of the doors, creating a cleaner look and removing the temptation for a potential burglar to attempt to gain access this way.
  • Internally glazed system, preventing sealed unit of the glass from being removed from the outside.
  • Fitted with toughened safety glass as standard with the option to upgrade to laminated safety glass.
  • Designed to allow a built-in tolerance to cope with material expansion and contraction when installed to south facing elevations and for marginal lintel deflections
  • Available with 2500mm2 or 5000mm2 colour matched trickle vents incorporated within a 35mm add-on above the top track should you need to comply with Building Regulations requirements.
  • Option for horizontal or vertical midrails to divide the glass or choose plant on bars stuck to the glass for a more traditional look
  • A bottom running system with a four wheel running carriage manufactured from tough glass fibre reinforced polyamide set around a maintenance free sealed ball-bearing.
  • Panel catch - Unique to SUNFLEX bifold doors our locking black PVC panel catch is provided when there is an odd number of panels folding in one direction. This holds the single access door on to the next panel and when all the doors are stacked open the special design prevents the single door being detached from the next door for peace of mind in windy conditions. Also prevents unwanted use and promotes correct operation of the doors providing the correct counter weight for effortless operation.
  • Finger cushioning gasket situated on the edge of each door. This double gasket seal provides a cushioning effect if fingers were to be trapped. Making these doors safer than conventional, internal, single wooden doors that do not come with finger cushioning gasket. 
  • Three standard frame colours: Slate Grey (RAL 7015) matt, Graphite Black (RAL 9011) matt or Anthracite Grey (RAL 7016) matt
    RAL 7015 Slate Grey matt RAL 9011 Graphite Black matt RAL 7016 anthracite grey matt
  • Choose from more than 200 aluminium RAL colours and finishes for your frame or opt for brushed steel effect, textured or woodgrain finish to ensure your doors perfectly complement your home.
  • Colour matched handles in line with the frame are designed to almost disappear whether the door is open or closed. Plastic black D handle used at the hinge to pull the doors closed.
  • Standard frame colours have colour matched hinges, other frame colours can have colour matched hinges as an upgrade or standard black hinges designed to fit in line with the black gasket of the doors..
  • Opt for a dual colour system with different colours on the inside and outside faces of the doors - perfect for matching the doors to both your internal and external decor of your property.
  • For powder coated aluminium we recommend a marine treatment if you are within 5,000 metres of the coast or around a swimming pool or near a chemical environment. Alternatively we can provide the frames in a silver anodised finish which does not have a painted surface and does not need the marine treatment.


Burglar-resistant fittings

Burglar-resistant fittings

Assembly shoes

Assembly shoes allow a fast assembly and precise adjustment of the vertical frame profiles

PAS 24 compliant

Meets and exceeds the requirements of PAS 24:2012 to achieve Building Regulations Approved Document Q security standard

Optional twin-lock-mechanism

Optional twin-lock-mechanism

Panel catcher

Panel catcher for additional security to fix the pass door to the adjacent panel

Mushroom-head lock

Mushroom-head lock for optimal tightness and increased security

Options from Sunflex handle series

Options from Sunflex handle series

Different kinds of locks available

Different kinds of locks available


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