Synseal Warmcore Bifolding Door

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Nick Dardalis

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Synseal Extrusions Ltd are a long established and well respected PVCu systems company with an extensive and quality range of PVCu windows and doors.  Well known for their K2 conservatory roof system, Global Roof, Shield and Synergy range of systems to name just a few.

Their latest product  is the Warmcore folding sliding door, introduced as a completely new door system by Synseal.

What is the Synseal Warmcore door?

the warmcore from synsealis a brand new door that  features aluminium  clad profiles for excellent u values.
The Warmcore from Synsealis a brand new door that features aluminium clad profiles for excellent U Values.

The Warmcore door is a brand new bifolding door marketed as latest generation “warm aluminium”.  At the core of it’s design is an aluminium clad multi chamber and insulated core that is a departure from the traditional aluminium profiles of many bifolding door systems available.

The Synseal Warmcore Bifolding Door benefits from very good thermal performance that will exceed current and future Building Regulations.  Changes in the Building Regulations have been known about for several years already with 2016 bringing yet more changes required to the overall Window Energy Ratings and U Values of windows.

Thanks to the way the Synseal Warmcore door is constructed the product is effectively “future proofed” against the upcoming changes in these Building Regulations.

Is Warmcore an aluminium or a PVCu bifolding door?

Essentially this is an aluminium door.  For the last few years, systems companies have long known that the bigger the thermal break within an aluminium door or window, the better the thermal performance.  Synseal have taken this concept a stage further by making the non metal core of the product much larger with only very small aluminium extrusions on the inside and outside faces. Added to this, the thermal core of this door and its multi chamber construction adds to the structural integrity of the product.

to achieve good thermal performance on aluminium windows, the thermal break needs to be as large as possible.
To achieve good thermal performance on aluminium windows, the thermal break needs to be as large as possible.

This in reality is no different to high performance windows.  As shown on the image here, the DF1400 outer frame of the SAPA Dualframe Si Window shows a small amount of aluminium profile external and internally with the bulk of the extrusion formed from the polyamide thermal break.

This larger than usual polyamide thermal break and much less aluminium than older generations of windows is what gives doors and windows their varying U Values and overall performance when used with good specification glass.  It is to be expected that future generations of aluminium windows will feature even larger insulators such as polyamide thermal breaks or polyurethane cores as featured in the new Senior Aluminium PURe range of windows.

the new senior aluminium window features polyurethane foam as a thermal break
The new Senior Aluminium window features polyurethane foam as a thermal break

So whilst this is a new product, the concept behind it could be argued is not new.  Indeed, aluminium clad windows have been around for over 25 years.  Those that remember the Smart Systems Duotherm range of windows and doors will recall this was an aluminium clad pvcu window that had PVCu profile internally and aluminium externally.

What are the advantages of the Synseal Warmcore bifolding door?

The Warmcore door is an aesthetically pleasing product that is slim and suits direct fixing thanks to its 70mm front to back dimensions.  There is a choice of external aluminium profiles available that include:

warmcore bifolding doors feature a range of profile and bead options.
Warmcore bifolding doors feature a range of profile and bead options.

Square profile design for contemporary looking doors, Profiled framing or “Pencil Round” design, an ovolo profile that will suit those seeking a more traditional timber look product and a chamfered design to mimic putty line windows or doors.

Additionally, there are three types of glazing beads available that also alter the look of the product although not all beads can be used with any frame combination.  The doors are internally beaded.  Square glazing beads can be fitted all round the doors, chamfered glazing beads are possible on the vertical parts of the door leaf only.  The flatline in appearance bead used for those that require a triple glazed Warmcore door is fitted all round.

Therefore it is important to remember that if you are having a triple glazed door with say, a chamfered frame you won’t be able to used the chamfered bead only the bead suitable for triple glazing.  Given the logical thicker unit that is triple glass, this is logical and sensible on behalf of Synseal.

A choice of colours and options.

Presently four standard colours are available for the internal and external aluminium profiles. These are standard White  and Cream that will colour match existing Synseal Conservatory Roof Systems, Grey RAL 7016 that is one of the most popular grey colours offered and Black RAL 9005.

Synseal advise that other RAL colours are available on special order.  It has been reported on another website reviewing the product that “Installers could have them sprayed”.  This is not recommended on a completed and fabricated product as there are complexities to changing the colour on any power coated product.  Not only will existing powder coating guarantees be compromised  but there are other issues when changing the colour of any finished product.

Professionals that understand aluminium products are all too aware changes to powder coated colours should only be carried out by companies experienced in on site powder coating and repairs. Additionally spraying is not how aluminium products are coloured.  They are powder coated which is not a wet paint or spray process.

Warmcore is not just a bifolding door

Should customers require single swing doors or French Doors to match the bifolding doors, Synseal offer a suite of products enabling single action left or right hung, open in or open out doors whether single or double leaves.

With the bifolding doors themselves maximum widths possible are 6000mm.  Doors (including outer frames) can be manufactured at 2400mm high, with maximum sash widths of 1000mm.  The maximum load per door sash is 100kg.  Whilst these dimensions will be suitable for most residential applications, other aluminium systems utilising the traditional thermal break methods can be made wider and much taller than Warmcore.  Schuco bifolding doors as one example can be made up to 3metres in height and 1200mm in width per leaf.  Other systems can be made at 2700mm high or more.

So whilst the Warmcore door from Synseal will be ideal for most structural opening sizes anyone wishing to have a door taller than 2400mm may have to look at alternative systems or liaise with Synseal to see whether it can be made taller than publicised.

Highly insulated profiles and quality glass mean a high performance bifolding door.

With U Values that can meet and exceed current and future Building Regulations, the Warmcore door offers good U Values but of course these can only work if the right glass specification is used.   Providing this is done you can expect U Values as follows:

U-value of 1.4 W/m2K with 28mm double glazing

U-value of 1.0 W/m2K with 44mm Triple glazing

The option to use standard double glazing is still possible with a U Value of 1.5 W/m2K.

Can we recommend the Synseal Warmcore bifolding door?

With a healthy bifolding door market and with many of the leading bifolding door companies reporting year on year growth in sales of their product, any new product into the marketplace is to be welcomed.  Examination of the section drawings and profiles demonstrates the Warmcore door to be an aesthetically pleasing, slim and attractive product.

Press images released by Synseal show the thermal core to be Orange in colour but we do not believe this will be visible on any inside faces such as those visible when any bifolding door is opened.  We are informed that all internal finishes will be black in colour.

Where the U Values of bifolding doors are important to a customer then this is a bifolding door with good thermal performance coupled with attractive hardware and good design. We await fabricator and installer feedback.

(Warmcore images courtesy of

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16:42 30 Oct 23
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