The Negative Synseal Reviews Explained

Google Synseal Reviews or Warmcore Reviews and the results are not positive.  A visit to the Synseal Group Reviews on Trustpilot reveals 93% rated as ‘bad’ with just 7% rated as ‘average’. Homeowners contacting our website also ask if they should steer away from Synseal’s products after finding negative Synseal and Warmcore reviews online.

This article addresses some of the negative reviews and importantly, also explains why Synseal, in many cases, is unfairly criticised. Read our full review of Synseal Warmcore doors for in-depth information too.

Synseal Reviews
Synseal offers the Warmcore suite of bifolding doors, sliding door and windows.

Information and advice about Synseal Reviews online.

Most of the negative comments centre around the Warmcore range of bifolding doors. On the one hand,  the Synseal reviews on Trustpilot are small in number, compared to over 500 reviews for Origin’s range of windows and doors. On the other hand, some of these reviews are so bad, we think they could unfairly impact sales of the Warmcore product.

Furthermore, many excellent businesses fabricate and install Warmcore are potentially losing out on good business as a result of these reviews.  Even more pertinent is some companies set up entirely on the back of the Warmcore product when it launched in 2015.  Synseal is a substantial systems company with some industry leading brands under its belt.

Moreover, is the Warmcore product good and are the negative Warmcore reviews and Synseal complaints justified?

The Warmcore System is a quality, fit-for-purpose product.

First of all, Warmcore remains fit-for-purpose and not sub-standard.  Our comprehensive review of the Warmcore bifolding door explains more about Synseal’s product.  The Warmcore system is an innovative hybrid system using a combination of a big PVCu thermal core with aluminium on the inside and outside faces.  As a system and as a concept, Warmcore is good.  However, like all door and window systems, it comes with certain characteristics within its design, manufacturing and installation.

The substantial thermal core provides excellent U-Values with standard glass units, where other systems need enhanced glass or triple glazing.  However, this is a PVCu core and entirely different from the polyamide core used in most aluminium systems.  It is also not as forgiving as polyamide meaning extra care in both fabrication and installation.

When Warmcore is incorrectly made and incorrectly fitted, the product is potentially problematic, such as bowed door sashes and even the aluminium capping coming off the thermal core.  We must stress this is not a design fault.  Any product not made to a good standard risks problems as a result.

Above all, the extrusions, thermal core, powder coating, components and hardware all meet or exceed current British and European Standards. Warmcore also meets Secured by Design for security as well as the relevant classifications for air wind and water and a 10 year guarantee.

Understanding the negative Synseal Reviews.

With many years experience in the fabrication and installation of windows and doors, we can see that the negative reviews around Synseal are seemingly as a result of incorrect fabrication and poor installation.  The Warmcore system itself is not entirely to blame.

Synseal, to their credit, responds to these reviews and stresses they do not manufacture the product. Synseals only designs and supplies the materials. It is Synseal’s network of nationwide fabricators making Warmcore. Also to their credit is Synseal acknowledging early versions of Warmcore had issues and these are now addressed.

Just like every other major systems company Synseal’s role is supplying bar lengths and accessories to their fabricators. They also provide training, tooling and overall support.  Schuco, Reynaers, Smart Systems, Aluk, SAPA Building Systems for aluminium work in exactly the same way.  Liniar, Rehau, Kommerling, Eurocell, Duraflex and others with PVCu also work in exactly the same way.

We can also tell you that every systems company like the aforementioned invests substantial sums in bringing a product to market.  Design, testing, independent certification, training and supply is an expensive and complicated process.  No systems company sets out to design a bad product. And Warmcore is not a bad product.

Furthermore, as with any new product, manufacturers and installers regularly working with it, provide feedback to the systems company. As a result, they continually improve their product throughout its life cycle.  Assuming Synseal supplies correctly extruded profiles to their fabricators, it is fabricators and installers apparently letting the company down from the online reviews.

Synseal works just like most major systems companies.

There are also comments relating to Synseal charging customers for site visits to inspect their product.  We can tell you they are not unique in this and other systems companies also charge.  The role of the systems company in the overall supply chain is rarely dealing with homeowners directly.  In these reviews, Synseal does clarify their role and how they work.

So we stress again, that the negative Synseal reviews are putting the blame on the designer of the product and the raw material supplier.  This is unfair when the negative experiences are down factors, many of which are clearly outside of Synseal’s direct control.  However, it does appear that Synseal needs to improve how it supplies Warmcore materials.

We understand that Synseal do fabricate some of their products as well, so for balance presume some of the negative reviews relate to doors coming out of the Synseal factory.

Our advice to Synseal is this:

  1. Get actively involved in not only assessing some of their fabricators better but also work closely with the homeowners to achieve a satisfactory conclusion.
  2. Provide better training to fabricators and installers of Warmcore.  Many of the problems would never arise with a correctly made and fitted product.
  3. Synseal must encourage these customers to leave further reviews once problems are fully resolved and the customer is happy.
Alufold Warmcore bifolds offer unique features you won’t find on other products.

Looking to buy Warmcore? Choose your fabricator and installer carefully.

Above all, do your research and check out who makes your Warmcore doors.  A good Warmcore supplier makes a fine product or sources it from a good fabricator. We stress again, Warmcore, like any other door and window, needs precise fabrication and correct installation.

The door and window industry is a competitive space with many different ways to buy windows and doors. There are some fabricators selling at rock bottom prices and reflected in the quality.  There are also excellent fabricators making outstanding products of the highest quality with a 1st-class service all round. Therefore, any product is only as good a who makes and fits it.  Importantly, the professional Warmcore fabricators and installers do not experience the issues raised by the negative Synseal reviews.

This is where we can help you.  Use our contact form on this page and get in touch.  We can put you in touch with Warmcore fabricators or suppliers that not only fully understand Warmcore, but they also make it well and know how to fix it.

One such Warmcore fabricator and installer working nationwide is Aluhaus in Nottingham.  Not only do Aluhaus make Warmcore well, but they’ve also re-engineered and enhanced it providing even more features and benefits over the standard Warmcore. 

Synseals’s Warmcore range is a good product and the negative Synseal reviews should not frighten you to death about the consequences of buying it. Contact us for further information, advice or where to buy.

If you make or fit Warmcore, please leave your comments below with your experiences.


Published on January 11, 2019

Reader Interactions


  1. Glenn says


    I am trying to source some replacement door handle spindles and securing screws for the Warmcore Bifolds. I have read that it is a recurrent problem but so far am struggling to find anyone that supplies only the spindles and screws as replacement parts. Does anybody know of anyone?

    Many thanks,

    • Nick Dardalis says

      Hello Glenn
      The best thing to do is a general search on google for Warmcore door manufacturers or Warmcore trade suppliers and see if they can help.

  2. Mr Arthur Harris says

    Can you please provide a list of approved / recommended suppliers for Warmcore bifold doors
    with an approved record of supplying a good quality product

  3. Ryan says

    Hi, We are looking at UPVC SASH windows and our local fitter has advised that he fits Synseal. We are also installing a small set of bi-folds. Do we avoid Synseal, as the google reviews are frightening! Thanks

    • Nick Dardalis says

      Hello Ryan, most of the negative reviews centre around the Warmcore product. For their broader range of PVCu windows and doors you should be fine.

      It’s worth speaking to one of their bigger fabricators who can also put your mind at rest. Worth getting in touch with the below.

      Pioneer Trading Company
      1-3 Red Barns, Warners Farm, Howe Street
      Great Waltham,
      Essex, CM3 1BN
      Tel: 01245 362236
      Fax: 01245 362421

      Hope this helps
      Kind regards

  4. Lisa says

    Had the warmcore doors for a year now.

    Only opened them twice and the second time couldn’t shut them and had to get 3 friends to lift them back in.

    Spent the last year chasing the installer who was chasing the supplier.

    We got no where.

    Decided this week to rip them out and get new opens fitted that are not warmcore.

    Very bad experience and tired.of being locked in without being able to open the doors.

  5. Peter Gray says

    Interesting read guys, totally agree. The warmcore product is a great product. We were an early adopter and for sure went through some teething problems making it and there were some product issues (like snapping handles for example) in those early days. These have all been over come now and I have to say we have no issues with it now with quality of product.

    As a manufacturer you have to be aware of things like ensuring the corners are done properly so they don’t open up for example.

    The fitting is also slightly different, for example we always send a YouTube video of how to install with every order prior to dispatch and encourage the fitters to watch. Of course not all do.

    I’m my vast experience of supplying warmcore across the UK it is 9 time out of 10 fitting issues that can quite easily be rectified.

    We have customers now that when taking their first doors weren’t too keen but now love the product and have no issues at all.

    For example the ability to toe and heel without deglazing is a real bonus, as everyone knows this can be an issue with newly fitted bifolds.

    Going back to you point about good and bad fabricators – we install this option (toe and heel) as a standard feature. Some don’t!

    In summary I’d definitely echo the point that Warmcore is a well engineered product and finding a good, quality, knowledgable fabricator is hugely important!

    • Dan Marshall says

      Hello Peter and Nick,

      Nice to get a manufacturers view on here. I purchased a supply only door in 2017 and installed it with my builder exactly to the instructions provided with the door. It’s level and plumb and fixed as instructed.

      Config is triple glazed O/A Sizes 3030mm x 2400mm (3.3.0). It’s a great door, quiet and super warm, and very robust. We selected it after viewing many of the systems readily available at the time.

      Over time it’s become more and more difficult to close the traffic door. I’ve made all the adjustments I can and essentially now my wife can’t close the door, and more often than not I now have to close it from the outside only, whilst applying my weight via knee and shoulder before the multi-point locks will engage. This has perplexed me somewhat over time and the other day I checked it for ‘straightness’ sure enough, the traffic door is bowed outwards at the top and bottom.

      I’m yet to contact my supplier about it but I am worried I’m going to left high an dry here.

      Is a 2017 door classed as an early example? The door doesn’t have warmcore handles as they were snapping at the time, so stronger examples (which don’t allow the leaves to sit open and parallel) were fitted.

      Also, Peter, would you be willing to share your youtube videos with me regarding installation, and in particular, heeling and toeing without deglazing? My doors have the adjusters installed (I know this because I shattered my first pane using them – they came with no guidance whatsoever).

      How do you suggest I proceed here?



      • Nick Dardalis says

        Hi Dan, great feedback thank you. You’ve demonstrated well what we say about all windows and doors. Well made and correctly fitted, they work and perform just fine. The thing about some systems is how easy they are to put together and fit. Some make it easy, others less so. And there are some systems that have no forgiveness if corners are cut even in a small way.