Sunflex bifolding door review

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Nick Dardalis

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Sunflex bifolding doors are premium quality doors, made in Germany and supplied in the UK. In our review of Sunflex bifolding doors, we take a look at their key features and specifications. We also explain what you can expect if you are thinking about a Sunflex Bifolding Door for your home.

review of sunflex bifolding doors

How we Research our Sunflex Bifolding Door Review

To review a product we see the product. Then we take a look at the specifications in detail, as well as the technical drawings and manuals.  As a result, we can provide an insight into the various features and specifications of a product.

Finally, we compare these with other systems. We also check out information provided either on the Sunflex website along with other literature and brochures.

About Sunflex Bifolding Doors.

Every one of these German-made bifolding doors comes through a UK network of approved installers. Sunflex follows a similar business model to companies like Origin. They too also make their bifolding doors and supply them to installers.

A quality bifolding door is only as good as its manufacturing and, importantly, its installation.  Consequently, any issues encountered with a product are primarily due to installation.  Importantly, Sunflex ensures that their authorised distributors receive full training at their Norwich head office.

Sunflex also offers technical support where required.  Together with their installer partners, Sunflex ensures the consistent quality of their doors with a long lifespan.  In our review of Sunflex bifolding doors, we examine these quality aspects of the product.

The Sunflex Bifolding door product range.

Sunflex provides no less than six bifolding door versions.  Moreover, these comprise aluminium bifolds, timber doors and hybrid doors being a combination of aluminium outside and timber inside.  There is also an internal version of their folding doors.  The Sunflex bifolding door range comprises:

  • Aluminium SF55 and SF75
  • Timber SF75h
  • Hybrid/Timber Clad Aluminium SF55c and SF75c
  • Internal bifolding door SF45

There is also the impressive SF55e, also reviewed, with virtually the same top specifications at a lower price.  

Sunflex Aluminium Bifolding Doors SF55 and SF75

In our review of Sunflex bifolding doors, we concentrate on the full aluminium versions, SF55 and SF75.  Here’s how they compare:

Sunflex SF55 Sunflex SF75
Best for new openings Best when replacing existing doors
55mm front to back frame dimension 75mm front to back frame dimension
Thermally insulated bifold door. Enhanced thermal insulation
Typical double glazed U-Value of 1.6Wm2K Typical Double Glazed U-Value of 1.4Wm2K
115mm sight line 115mm sight line
Maximum panel sizes 1200mm x 3500mm Maximum panel sizes 1200mm x 3500mm
Square edge appearance Square edge appearance
Matching square edge windows Matching square edge windows
Inline door handles don’t interrupt glass line Inline door handles don’t interrupt glass line
Mitred outer frame Mitred outer frame
Accepts 24mm, 28mm, 30mm and 36mm glass units Accepts 24mm, 28mm, 30mm and 48mm glass units
Trickle Vent option if required Trickle Vent option if required.
Choice of three thresholds Choice of two thresholds
Shootbolts available with twinlock security Shootbolts available with twinlock security
Offers optional midrails and glazing bars Offers optional midrails and glazing bars
Available as 90 degrees and 135-degree corners with floating mullion Available as 90 degrees and 135-degree corners with floating mullion
Create curved or faceted bifolding doors. Create curved or faceted bifolding doors.

Choosing a SUNFLEX bifolding door.

The SF55 offers very similar features to the SF75 model but without the enhanced thermal performance or weather resistance.  In other words, both provide great U-Values in line with other folding door brands. The Sunflex SF75 like the Schuco ASS80 over the ASS70 is an enhanced model. That said, Sunflex doors perform considerably better (as low as 0.9W/m²K) than Schuco, Origin and Sunfold systems with the appropriate glass.

We have not included the internal SF45 as we are concentrating on the Sunflex doors suitable for external applications.  We have to give credit to Sunflex and other companies like Schuco, Sunfold and others. These take the trouble to offer an internal bifold door in their range.  A regular bifold while perfectly suitable for interior applications can be surplus to requirements. Often, thermal breaks, enhanced security and weather performance is not required. You pay for these extras on a door that can be much simpler when fitted inside the home.

Threshold options on Sunflex Aluminium bifolding doors.

The threshold on a bifolding door is a critical consideration in a home improvement project.  Sunflex bifolds achieve a flusher threshold than other brands such as Origin, AluK, Schuco and Smart Systems.

Both SF55 and SF75 Sunflex doors offer a flexible threshold and cill arrangement. You can choose a cill, no cill, good for opening inward or outward doors.  You also get a ramp type threshold on the SF55 model. The ramp-type threshold is only 13mm high and is suggested for doors that are not exposed.  It does not have the weathering capabilities of the rebated threshold.

Handle options on Sunflex Bifolding Doors.

One of the essential features of any bifolding door is the quality, and visual appeal of the door handles. Origin, as a direct competitor to Sunflex, offers the Hafi handles that are gorgeous to use and look at.  Schuco offers their own unique range of door furniture, and Reynaers provides the Purity range that we think is one of the best of any bifold door furniture range.  However, the handle offering on the Sunflex doors is just as appealing. Air doors provide the Serenity range of handles. These too are exclusive, premium quality and very

With a Sunflex bifold, you have handles which are finished in-line with the door frame.  Inline door handles help retain a uniform appearance. Inline handles also avoid the 90-degree return of the handle going into the glass line.  This is very similar to the handle you get on a lift and slide patio door.

But for those that do want a more tradition latch-type handle with a lever, it is available.  The slave door handles are available as a flat or a cranked style.

Other features in our review of Sunflex bifolding doors.

A Sunflex folding door may cost you a little more than other favourite brands such as Origin and Schuco. However, there are actually quite a few features of a Sunflex door that we say make it arguably more appealing.

Sunflex Bifolds are super slim.

One of the standout features of the Sunflex bifold is its 115mm sight line.  This comfortably places the product within the top 10 thinnest bifolding doors available in the UK.  It beats Origin doors comfortably for thin lines and is even thinner than the Schuco door.  Most of the recent bifolding doors to hit the market in recent years have used the Schuco ASS70 FD as the benchmark for sightlines and the Origin door for quality. If you want a bifold that is thin, take a look at Sunflex.

Sunflex bifolds are great to look at.

Sunflex bifolding doors offer square line profiles. They do not offer the chamfered appearance found in Aluk, Smarts, Origin, SAPA and other folding doors.  And we agree.  The 115mm mullion sight lines work better with a square profile and doors look good in the open position.

The visible hardware on any bifold is not the most attractive; Sunflex uses highly modern carriage wheels, door hinges and handles. These work well with the square and thin nature of this door.  We have seen this door many times and can tell you it is a very good looking door indeed.

Sunflex bifolds have the expected ‘German Engineering’.

The handles feel super positive in use, the sliding action of the doors is smooth and light.  You get a lovely positive engagement on the door catches that hold the doors in the open position.  Where other brands stick to plain magnets, Sunflex has clearly looked at the small details of their doors. Sunflex provides visible and hidden engineering that is typical of a high quality door.

You get tolerance in the doors to take into account thermal expansion on South facing elevations.  There is a choice of static or moveable corner posts with 135 degrees or 90 degrees.

Sunflex doors will appeal to those looking to create a more ambitious extension. Sunflex bifolds even work within a faceted or curved structural opening.  You also get the choice of midrails as well as glazing bars to create a steel look bifold. The shoot bolts in a Sunflex intermediate door are available with four locking points – other brands only offer two.

Sunflex bifolding doors offer more than just RAL colours.

While it is technically possible to offer anyone’s bifolding door in special colours outside of the RAL colour chart, many don’t do it.  This is because of the extended lead times and overall hassle factor for many installers.

A Sunflex bifold gives you Silver Anodised, brushed steel, textured aluminium and woodgrain effect aluminium.  Colour matched handles are also available as is a marine grade powder coated finish.

Another thing Sunflex has done is joined the growing trend for ‘pre-anodising’. Pre-anodising is the new alternative to chemical cleaning and pre-treatment of aluminium extrusions prior to colouring for coastal locations. We can tell you that the pre-anodising method offers better preparation of the aluminium.  It also provides superior adhesion of the polyester powder to the extrusion. It is very much the current way of powder coating aluminium extrusions, with excellent results for corrosion protection in the longer term.

More features found in Sunflex Bifolds.

You may be interested in these other great features found in Sunflex doors.  Many of these you don’t find on other brands.

  • Unique part-vent position allowing the doors to be partially opened for ventilation when the doors are locked shut.
  • Option for integrated tilt and turn window within the bifold door panel
  • Industry-leading weather testing (air permeability, water tightness and wind load)
  • BSI Kitemark™ (the only German made bifold doors that carry this prestigious quality award)
  • Building Regulations approved document Q PAS 24 accredited
  • Secured by Design awarded.
  • Larger panel sizes of up to 1.2m wide and up to 3.5m high.

Our review of Sunflex Bifolding Doors. Should you buy it?

The aesthetics, the engineering, the slim sight lines, the colour options and the capability for curves and facets are great reasons to consider Sunflex SF55 and SF75 bifolding doors.  Sunflex like Origin and Sunfold, to name just two, are amongst a rare group of systems companies that make their doors.

If you are considering the other two or other premium brands, it is worth comparing them with Sunflex. You will arguably find Sunflex and Sunfold a closer comparison for features and sightlines.  You won’t get the super fast lead times or 20-year warranty that makes an Origin door a best-seller or the Schuco so popular, but we’d suggest you also consider it with them.   It’s thinner, has bigger size capabilities, has an entirely different aesthetic.

The ability to lock in the partially open position and the possibility of having a tilt and turn window in a door panel are also appealing.

Contact us if you would like more information or have any questions or comments on our review of Sunflex bifolding doors. We’d especially like to hear from you if you already have Sunflex doors in your home and what you think of them.

Main Image courtesy of SUNFLEX.

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16:42 30 Oct 23
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07:03 11 Sep 23
Update - A second email to nick for help on bifolds resulted in a detailed informative reply even on a Sunday ! This guy is so knowledgable and helpful .I approached Nick for an independent view on sliding doors v bifold and the different brand options . His reply was extremely detailed and prompt and allowed me to navigate this often confusing world in a much more informed way . Thanks so much Nick
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