Download our brochures


Slimline timber bifold doors - available with double or triple glazing

The SUNFLEX SF75h timber bifold doors have the slimmest sight lines in Europe, just 122mm. This truly highlights SUNFLEX’s commitment to quality and design.

All timber for our bifold doors is sourced from sustainable forests. The standard timber bifold doors are Meranti (hardwood) and Nordic Pine (knot free-softwood), while other timbers such as American White Oak, Larch or Douglas Fir are available by special order. The natural beauty of the wood is enhanced by SUNFLEX’s finishing techniques, resulting in the finished product being comparable to that of high quality furniture.

Key features

  • Slimmest sight lines available for timber bifold doors - 122mm.
  • Secured by Design award. Designed and installed to police preferred specification.
  • Extremely versatile, up to 25 metres with 12 panels in each direction, open in/out low or weathered track option.
  • Sustainable timber, Meranti hardwood or Nordic Pine as standard with other timber types available, eg Larch, Oak or Douglas Fir.
  • Continuous double gasket seal for supreme weather performance.
  • Can accommodate double or triple glazing.
  • Range of stain and paint finishes.

Versatility in design

The folding door system may be folded to the left or the right, open to the inside or outside. The SF75H can have panels all folding the same way or split with a number folding to each side. In addition, angle units of 90o and 135o or segmented units allow the versatility of design needed to create large bay or corner openings.

SBD-Logo.png PAS24-Logo.jpgspacer.png




Whatever your requirements our bespoke range of timber and aluminium bifold 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 timber bifold 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.


Finishes on Meranti

Below are images of our range of standard stain finishes available on our standard hardwood Meranti.

  • Standard stain finish for meranti in ash from IDSystems
  • Standard stain finish for meranti in pine from IDSystems
  • Standard stain finish for meranti in old pine from IDSystems
    Old pine
  • Standard stain finish for meranti in light oak from IDSystems
    Light oak
  • Standard stain finish for meranti in dark oak from IDSystems
    Dark oak
  • Standard stain finish for meranti in teak from IDSystems
  • Standard stain finish for meranti in mahogany from IDSystems
  • Standard stain finish for meranti in rosewood from IDSystems
  • Standard stain finish for meranti in walnut from IDSystems
  • Standard stain finish for meranti in ebony from IDSystems


Finishes on Nordic Pine

Below are images of our range of standard stain finishes available on our standard softwood Nordic Pine.

  • Standard stain finish for pine in ash from IDSystems
  • Standard stain finish for pine in pine from IDSystems
  • Standard stain finish for pine in old pine from IDSystems
    Old pine
  • Standard stain finish for pine in light oak from IDSystems
    Light oak
  • Standard stain finish for pine in dark oak from IDSystems
    Dark oak
  • Standard stain finish for pine in teak from IDSystems
  • Standard stain finish for pine in mahogany from IDSystems
  • Standard stain finish for pine in rosewood from IDSystems
  • Standard stain finish for pine in walnut from IDSystems
  • Standard stain finish for pine in ebony from IDSystems


Finishes on Oak

Below are images of our range of standard stains and finishes available on Oak, which is available over our standard Nordic Pine or Meranti.

  • Standard stain finish for oak in ash from IDSystems
  • Standard stain finish for oak in pine from IDSystems
  • Standard stain finish for oak in old pine from IDSystems
    Old pine
  • Standard stain finish for oak in light oak from IDSystems
    Light oak
  • Standard stain finish for oak in dark oak from IDSystems
    Dark oak
  • Standard stain finish for oak in teak from IDSystems
  • Standard stain finish for oak in mahogany from IDSystems
  • Standard stain finish for oak in rosewood from IDSystems
  • Standard stain finish for oak in walnut from IDSystems
  • Standard stain finish for oak in ebony from IDSystems
  • Standard stain finish for oak in oiled from IDSystems
  • Standard stain finish for oak in clear from IDSystems


Please note that due to the variation of the grain in timber, any colour samples provided are designed only to give an indication of the shade and may not match the finished product.

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 SF75H bi-folding door by IDSystems



RAL swatches for the SF75H 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. 




The manufacturer recommends panel widths do not exceed 1,100mm and a maximum height of up to 2,900mm. Heights greater than this, can be achieved. Please contact our technical department for advice.

The system can cater for very large openings - up to 25 metres with 12 panels in each direction.

Fixed glazing can be built above the door system. Where this is required for wider openings strengthening profiles are incorporated within the door framework to aid lateral stability.


The Sunflex SF75H is manufactured from triple-laminated solid timber sections. These sections have been stabilised at stress points and bonded back together with opposing grains, which creates added strength whilst preventing warping and twisting.

Note: Inferior solid timber doors fitted with standard joinery hardware, that have not been precision engineered and laminated in this way, will potentially experience severe problems with temperature and climate changes over a period of time, causing them to expand and stick or shrink and leak.

Track options

There are two choices of track; a standard weathered track for a severe weather rated system and a low threshold track. The low threshold track complies with Building Regulations Document M for disabled access.

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.

Low threshold track

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, whilst offering a smaller difference in floor level than the weathered track.

Download track options (ZIP file 404KB)


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. First opening pair (or alternative Lead door) consists of a two-point top and bottom shoot bolt mechanism. The locking system is incorporated within the framework within each intermediate panel, operated by an internal flush handle.

For improved security, all Sunflex bifolding 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 bifolding 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. For single access doors or on the lead door of folding sets, a mortice lock can be fitted where a latching position is required for added convenience. Additional mortise locks can be fitted to the top or bottom of the door if required, or you can add multi-point locking.

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 achieves BS EN 12207 – air permeability Class 4, water tightness Class 9A (900Pa), wind resistance Class 4.

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 closes the gap effectively. It is recommended that some form of drainage and a slope away from the doors are integrated.

Operating system

The stainless steel bottom 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 unique design of running gear mechanism concealed between the door panels offers improved security, as the running gear which secures panels into the track is unable to be attacked from the outside.

Note: With top hung doors you are reliant on your lintel supporting the structure above as well as carrying the large weight of the door system. This can often cause the lintel to deflect, which in turn leads the bottom carriage of the door to reach its maximum tolerance. Resulting in a door that becomes extremely difficult to open and close at the lintels tightest point and is not adjustable.

On our bottom running systems, all of the weight is taken in the base track. The running gear at the head of the doors is self-adjusting meaning should there be any small amounts of movement in the building the system will continue to freely operate. Like all of the other Sunflex systems the running carriage runs in a specially designed channel in the sides of the bottom track. This allows for clearance of the wheels over any debris that enters the track.


The natural character of wood is perfectly preserved by using Sikkens micro-porous water based wood stains (ie they contain no harmful solvents) in a variety of stain colours. Alternatively, the timber can be paint finished to any RAL colour with over 200 colours available. You can even have different colours or wood stains inside and outside. As standard Sunflex timber door systems are fully finished which consists of one basecoat and two topcoats, other finishes including oil are available upon request.

All handles are specially designed to complement the door system. Standard colours are white RAL 9016; black RAL 9011; aluminium RAL 9006; or standard brown. Gaskets are black, with hinges mounted within seal sightline available in white RAL 9016; black RAL 9011; or standard brown. Other RAL colours can be applied to the handles and hinges if required or alternatively there is a stainless steel handle option.

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

Handles and hinges are made of cast-alloy, handles are sprung-loaded and flush-fitted to enable door panels to stack flat when fully opened. Optional lever handles are available upon request for single access door or lead doors.


Trickle vents with an airflow equivalent to 2,500mm2 or 5,000mm2 can also be incorporated through the head track.

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.


Designs can be customised according to your preference - the options includes mid-rails, mullions, plant-on bars with dummy spacer grids, arched heads, timber fillets, deeper top and bottom profiles and solid in-fill panels, among many others.

Complete system

The SF75H timber bifolding door system can also be used to manufacture single doors, French doors and fixed glazed screens. Sunflex uses matching profile sections for these products to achieve an aesthetically uniform appearance throughout.


The SF75H timber bifolding door system is internally glazed and can accommodate glazing ranging from 4mm clear toughened glass up to a sealed unit of 40mm.

Our standard 28mm unit double glazed 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 to comply with Building Regulations for safety and thermal efficiency.

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

Alternatively the system can be triple glazed to achieve an overall system U-Value of 1.0W/m2K.

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.

Quick quotation form

My form



Bifold doors Sliding doors Other

Aluminium Timber Composite

All fields marked with * must be filled in.