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Aluminium bi folding doors - SFK20:20
The SFK20:20 folding sliding door system is the latest Sunfold product to hit the market. With its quality craftsmanship and specialist design, the SFK20:20 is available in a number of configurations and can meet a range of budgets. Similar to that of its counterparts such as the SFK70, the SFK20:20 bifolding aluminium door system is the ideal solution for kitchen/diner extensions, balconies, sunrooms, conservatories and even pool areas. A range of windows and doors are also available to complement the folding sliding door frames.
Features
Each panel can be manufactured to maximum widths of up to 1000mm with heights of 2500mm- Doors will stack inside or outside, left, right, or split
- Bottom rolling (floor supported) systems are available
- Slim sightlines - only 103mm
- Marine treatment available for salt-water environments
- Finger safe and severe weather rated seals and gaskets
- Three tracks available, flush, low-level semi-weathered and fully weathered
Thermally broken top and bottom tracks- U-Values of between 1.6 to 1.8 W/m²K with standard glass (lower values possible)
- Complies with the revised part of Document L Building Regulations (October 2010)
- Frames and mechanisms fully guaranteed for 10 years
References
- Watch the Sunfold show-reel
- Folding sliding door feature check list
- Stainless steel handle options, only satin (brushed) and polished stainless steel are recommended for external use
- Marine treatment for superior salt-water protection
- RAL colour chart
Configurations

The SFK20:20 doesn't have the same flexibility of the SFK70 system but a suitable configuration can be provided for any number of panels. The following diagrams show the configuration options for 1 to 7 panel sets.
Each of the diagrams below show opening-out door sets. For each there are three other variations as the diagram to the right shows.
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Tracks
Tracks are available at three levels, flush (with brush seals), low-level semi-weathered and fully weathered.
The tracks can be recessed into the floor to allow for smooth transitions between internal and external spaces. The track type determines both its level below the finished floor level (including carpets, tiles or other floor coverings) and the weather-tightness of the door sets.
NB: With all track types the drainage of water running down the front of the doors and out from the centre of the track needs to be considered.
Flush track

- The smoothest floor transition available
- Track can be recessed 38mm below the final finished floor level on the inside and outside
- Brush seals run along the inside and outside track edge
- Drainage needs to be consider along the outside track edge.
Technical details
- Bottom running opening out
- Bottom running opening in
Low-threshold semi-weathered track

- A minimal transition between internal and external floor levels
- Track can be recessed 20mm below final finished floor level on one-side and 38mm on the other
- Gasket seal on one track edge provides a watertight and airtight barrier
Technical details
- Bottom running opening out
- Bottom running opening in
Fully weathered track

- The maximum amount of weather protection available
- Triple gasket seals provides complete protection against water and air infiltration
- Track can be recessed 20mm below final finished floor level on out-side and 71mm on the other
- Ideal for coastal facing properties or areas that experience severe weather
Technical details
- Bottom running opening out
- Bottom running opening in
Security

- Lead doors are fitted with a 3-point locking mechanism that meets insurance companies’ requirements
- Intermediate panel joints are held closed by internal shoot bolts top and bottom operated by a flat, colour matched, sprung handle
- All key locking cylinders are Sunfold unique high security locks
- Locks can be supplied keyed-alike if more than one door set is required

Unique high security locks
Our highest security locking system offering unique and advanced security features.
• Anti-pick shaped pins
• High security six pin cylinder
• Cylinder protected against drilling
• Magnetic pin protects against unauthorised entry
• Cylinder protected by anti-wrench reinforcement
• Magnetic key with moving component protects against unauthorised duplication
• Protection against forced entry through the use of 'Bump Keys'
• Possible to incorporate a master key system
Intelligent keys
Extra security with our unique key controlled lock changing system.

- A construction key with red insert is used during installation
- Three main keys with yellow inserts. Upon completion these keys are used to recode the cylinder and exclude the construction key

- One emergency key with white insert. If a main key is lost or stolen this key will
recode the cylinder again and exclude all previously used keys
(Additional and replacement keys are available on request. Along with other high security lock products)
References
Colours & finishes
Standard finishes





- Powder coating is available in any RAL colour to suit any style and taste
- Gaskets are supplied in black as standard
- Hinges and magnetic panel catches are supplied in anodised black (C35) or silver (EV1)
- Lever handles are colour matched or brushed/polished stainless steel options are available from our in-door range
- Shoot-bolt handles are colour matched to the frame
Marine treatment
Marine treatment is available on aluminium systems to protect against the aggressive corrosion of salt-water environments. Our marine treated system provides high quality protected components combined with a powder-coating process that is certificated to Qualicoat sea-side class.
Disclaimer
The colours shown on this page are intended as a reference guide only. The RAL colour simulations displayed may not exactly match RAL®-identified colour standards. Please use current RAL colour publications for accurate colours. Computer monitors and web browsers generally show different colour values so colours will change slightly between different systems and different screens. The colours on this site must not be printed and used as a reference.
Glazing

- The SFK70 will only accommodate 28 mm glazed units
- Our standard 28mm unit comprises two panes of 4mm clear toughened glass, with an argon gas filled 20mm cavity. The inner pane is equipped with a Low E (soft coat) thermally efficient coating. Units are manufactured to BS6206A and BS5713
- Standard glass units provide a centre-pane U-value of between 1.1 and 1.2 W/m²K
- Many solar control and tinted glass options are available
- Glazing bars and solid (non-glazed) panels can be incorporated into your door design
- Venetian blinds are available to sit within the glazing cavity with manual ‘cord’ or electric 'battery’ operated controls
Anti-sun tinted glass
Anti-sun tinted glass is available in a number of colours, we promote green and blue tinted options. The tint can be used for visual appeal, to reduce glare or where a degree of solar control is required.
Reflex® glass
Reflex® glass can be provided as an upgrade option to our standard glazed unit. This 'smart glass' or 'solar control glass' is it is more commonly known, uses an invisible metallic coating which is applied to the glass using the latest coating technology. It provides additional performance and energy saving benefits in comparison to standard glazed units.
Benefits of Reflex® glass...
The invisible metallic coating on the inner surface of the external pane reduces the solar heat energy that can enter the room. Solar heat transfer is reduced by up to 75% compared to a standard double glazed unit. The subtle light blue tint reduces glare by up to 44% but still ensures good light transmission for both visual and thermal comfort.
The centre-pane U-value is reduced to 0.9 W/m²K with argon gas. This low U-Value offers improved insulation and reduces heat transfer through the glass. With better insulating glass the room will stay warmer for longer in winter and cooler for longer in summer, saving heating and air-conditioning costs.
An 'easy clean' external surface treatment to the glass reduces the need for cleaning and makes stubborn dirt easier to remove. The hydrophobic polymer coating promotes water run off which washes dirt and mess away with rain or water sprayed from a hose-pipe keeping the glass looking fresher.
The insulated glass units are fully guaranteed against unit seal failure due to the latest dual seal high performance manufacturing techniques. Using the very latest robotic manufacturing systems means that the glass is only touched by human hand at the very end of the process when it is 100% quality inspected.
Reflex® is a cost effective solution for reducing solar heat and allowing for more comfortable living in summer and winter. In-glazed blind systems cannot be incorporated into Reflex® glass units but are not needed to help reduce light and heat penetration due to the other benefits provided. Reflex® is a more cost effective solution for to reducing light and heat penetration than in-glazed blinds.
Bespoke design details
It is possible to incorporate glass design details into or onto the glass of you doors.
- Glazing bars can be fitted into the cavity of the glass unit.
- Leading or aluminium bars can be applied to the external face of the glass.
- Logos, designs and other visual details can also be sandblasting into the glass or applied as opaque vinyl stuck onto the glass.



We are happy to investigate requests for specific design details but require information on the specification that you would like. Some design detail options are not possible with in-glazed blinds or high-performance glass units.
Ventilation
Ventilation is often required by building regulations. Options can be incorporated into the door systems for rooms that do not have any other provision through windows, doors or ventilation systems.
Through-frame trickle vents
Through-frame vents are incorporated through the frame or a profile added to the frame providing a neat and un-obtrusive ventilation facility.
- Our standard through-frame trickle vents provide ventilation of 2500mm² equivalent area (as per BS EN 13141-1:2004) per vent
- A maximum of one vent for each panel in the system can be installed
- An add-on to the top of the system is required for the vents to fit through
- Vents can be supplied in black or white as standard.
- The body of through frame vents can be supplied to any RAL colour.


In-glazed vents
In-glazed vents can be incorporated when through-frame options cannot be used. The vents sit on top or the glazed units reducing the glass height.
- Our standard in-glazed trickle vents provide ventilation of 4100mm² equivalent area (as per BS EN 13141-1:2004) per metre of vent.

Other options
Glass with in-glazed blinds
Glass units can be provided with Venetian slated blinds manufactured within the cavity, between the external and internal panes of glass.
- Provides privacy for over-looked rooms
- Removes the need for the extra cost of retro-fitted curtain or blind solutions
- Blinds do not need cleaning as they are encased away from dust and dirt between the glass panes.
- Blind slats are supplied in silver as standard, white and cream slats are also available
- Units provide a centre pane U-value of between 1.1 and 1.2 W/m²K
- In-glazed blind can be incorporated into double glazed units up to 1200mm wide
Manual 'cord' controlled blinds
- In-glazed manual 'cord' controlled blinds are supplied with transparent mechanisms and grey cords as standard.
- Mechanisms are also available in grey and white, cords in black and white
Watch a video of manual blinds in use




Electric 'battery' operated blinds
Watch a video of electric blinds in use



In-glazed blind systems cannot be used in connection with triple glazed units or high-performance glass, such as Reflex®, with specialist coatings on the inside face of the glass panes.
Fixed panels
- Fixed panels provide glazed openings with no opening function
- They allow for the maximum amount of light with the minimal amount of frame
- Panels can only be supplied as single panels
- Fixed panels have a slimmer frame than that of a folding sliding door panel. 40mm add-on profiles can be supplied to the top and bottom of a fixed frame to increase the frame size if required.


