Which are better made, Aluminium or PVCu Windows

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Nick Dardalis

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PVCu Windows have improved substantially in recent years. Today you will find some high-quality plastic windows that are extremely energy-efficient, very secure and with fine detailing.

There are premium uPVC windows available such as authentic sash windows, timber alternative and timber replacement windows as well as flush sash windows.  You will also find PVCu windows that have vastly improved their foils to make them look better than the PVCu wood grain windows of previous years.

aluminium or pvcu windows

Compare aluminium and PVCu windows side by side and decide what is better made.

Even the best upvc windows, are manufactured in a way that is completely different from aluminium windows.  This will be particularly evident in the window corners and where the window mullions and transoms meet the frame.  On PVCu windows that have a welded and not a mechanically joined construction like aluminium there can be inconsistencies in the way corners are manufactured and cleaned that with some PVCu windows is nowhere near the high quality of a hand assembled aluminium window.

There are of course, fantastic PVCu windows such as those from Masterframe, Residence 9, Liniar and many others that are mechanically joined to replicate traditional joinery and these windows have a far better corner construction than their welded counterparts.  However, if you are very particular about the quality of your windows, it is worth looking at how these windows are finished and you will quickly see the advantages of the aluminium window construction over PVCu.

How are the corners joined on a PVCu and an aluminium window?

UPVC windows with welded corners are placed in a welder.  They have both corners placed against a hot plate with a non stick sheet that heats and melts the plastic.  Once this is done the plate moves out of the way, the heated corners are fused together and bond as the corner of the window cools.

Once the weld has cooled, there is overspill on the corner that needs to be cleaned off.  This is placed in a corner cleaner which uses a sharp metal component to clean the overspill off the corner and create the finished window.  Often this corner will also be hand checked to ensure it is done correctly and a manual tool may be used.

In both processes, the operator needs to stand away from the machinery.

On an aluminium window, this process is by hand.  The corners have cleats and chevrons applied to the inside of the aluminium profile. Small gap sealant is applied to weather seal the corner and they are then  placed in a crimper.  The sides of each corner will be connected using the human eye and then the window will be crimped to mechanically bond the finished corner.

There are mechanical corner crimpers available that can automate this process, but even many of the best and largest aluminium window manufacturers prefer to use hand crimpers rather than mechanical as the finished process by hand creates the superior corner.

In this process, the operative remains close to the window to check the quality of the corner.

the aluminium window is placed in the crimper and checked by hand before the corner is joined together
The aluminium window is placed in the crimper and checked by hand before the corner is joined together

Comparing the welded corner against the hand assembled aluminium window.

The differences in finish on a PVCu and an aluminium window are very easy to see. When you compare the two finished windows.  The corner cleaning of the PVCu window can sometimes be irregular and it’s rare to see four identical and consistent corners on plastic windows.  Aluminium windows tend to have much more consistency on all four sides.

The welded corner found on a PVCu Window does have advantages.

One advantage of the welded corner used in PVCu windows is that these corners are completely sealed from any possible water ingress because they are welded together.  This is different from an aluminium window that has corners mechanically joined as they cannot be welded on most standard windows.  Is this an advantage?

It is fair to say that there are obvious advantages to a welded window with completely weathertight corners, but it is unlikely that driving rain or extreme weather would focus purely on the window corners rather than the overall window itself.  It is also important to consider that all types of windows, irrespective of their construction have to undergo industry recognised testing for air, wind and water penetration.

Therefore, if a window has passed these tests under controlled conditions then both types of windows are considered weather resistant under the conditions set down by industry tests and standards. Both welded and mechanical corners would undergo the same weather performance testing.

In the case of aluminium windows, manufacturing must be carried out in accordance with the fabrication manuals of the systems company that designed it.  These fabrication manuals will insist that small gap sealant is used before the window mitres are assembled to ensure a good seal exists where the two corners of an aluminium window meet, seal and are crimped together.

What about the window mullions and transoms?

inside view of welded mullion on a plastic window with sash either side
Inside view of welded mullion on a plastic window with sash either side

The mullions and transoms on a upvc window are still welded together in the same way as the outer frames and vents.  You will often see a V Groove on plastic window which is part of the manufacturing process, although PVCu windows can also be mechanically joined at the mullions and transoms.

the inside of a wood effect aluminium window with mechanically joined mullion.
The inside of a wood effect aluminium window with mechanically joined mullion.

Aluminium Windows all have mechanically joined mullions and transoms and typically this creates a much cleaner mullion and transom than a upvc window.

You will always find windows of different quality.

It is very important to remember that the manufacturing process of PVCu windows is just one of many reasons why they are cheaper than aluminium windows.

There are many different sorts of upvc and aluminium windows available and you will see different features in the construction of each.

However, the joining process of aluminium windows is largely the same across all products and the manufacturing process of aluminium generally produces a much cleaner, smoother and better finished window.

The welding process of plastic windows will also vary from product to product but it is important to remember that in making plastic windows, all processes are largely automated whereas aluminium windows remain hand made and assembled like traditional joinery.

So next time you are in a window showroom looking at both PVCu and aluminium windows, have a look at how the corners and window mullions are joined and made on both systems and decide what window you prefer the look of.

Contact us for further information and where to buy the current range of aluminium window for your home.

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16:42 30 Oct 23
Nick responded incredibly quickly to my enquiry (on a Saturday too!), and was able to offer invaluable advice on both aluminum systems and manufacturer / suppliers. Thanks Nick!
chris steerchris steer
16:18 09 Oct 23
Had a meeting with Nick during the grand designs show. Was extremely helpful and professional would highly recommend
Chris WesthorpChris Westhorp
19:55 13 Sep 23
Extremely helpful with pointing us in the right direction to find the products we required and suggesting firms that could reliably fit them.Nick was quick to reply and very detailed in his advice.Highly recommend reaching out to them.
Cathy GreenwoodCathy Greenwood
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
Anthony CraigAnthony Craig
12:45 05 Sep 23
This is a must site for anyone looking for advice. Great service and very quick answers to questions. Nick has been of great help quiding us through the maze of aluminium products. Thank you
Philip DuffieldPhilip Duffield
20:24 26 Jul 23
I contacted Nick @ ATS for guidance on what aluminium sliding door systems would be suitable for an opening in an extension that is going to be both wide and tall. He came back really quickly with very detailed and incredibly helpful advice. He is clearly extremely knowledgeable about the systems on the market and their respective features and capabilities. If you’re feeling a bit lost by the overwhelming range of choices out there, I’d definitely recommend contacting him.
Dariush HekmatDariush Hekmat
17:25 19 Jul 23
Nick's advice is great. He is always quick to respond and spends time on responses, which really help to make an informed decision.
Alan FosterAlan Foster
07:51 12 Jul 23
Absolutely fantastic. Asked for advice about replacing Crittall (?) windows late last night and early this morning received 3 great suggestions and contact information for suppliers
Rachel LauRachel Lau
09:24 16 Jun 23
Fantastic website full of valuable and pragmatic advice about product selection and comparison: no other website gives information like this. Truly written for public interest. Don't hesistate to reach out to Nick via the mailing system. He responds very quickly, is friendly, and has very sound and high knowledgable advice. I have already shared this with my friend planning her own grand design.
guard Charlieguard Charlie
12:28 14 May 23
I emailed this company just on the off chance they could help me with new magnetic sliders for my patio door. They were not able to supply those but were so very helpful providing me with the name of a company who could. I am so very grateful at the great service. Dare say customers must be very happy. thank you so much.
Benjamin LewisBenjamin Lewis
10:06 04 May 23
Nick is very helpful indeed. Extremely knowledgeable on bifolds which was in relation to my query. Great website as well, some very useful articles. Particularly appreciated the article that lists all the major bifold options in order of their sightlines! Thank you!
P JonesP Jones
08:07 15 Apr 23
I asked Nick some questions about an installation we were considering and he replied within hours with some very useful suggestions that will probably lead us to using a different make and supplier. Thanks, Nick. Great work.
Nicholas WallNicholas Wall
13:18 02 Apr 23
Looking for fair and honest expert advice on all aspect of aluminium windows and doors? These guys will arm you with all the information you need to make the RIGHT choice in a highly complex, crowded marketplace. post a question and you will get a very quick professional answer you can rely on being based on fact. Thanks guys!
Giorgia SiriacoGiorgia Siriaco
16:25 21 Mar 23
After a lot of research to find doors that would meet our unusual size requirements and feeling increasingly uncertain about the best way to spend our small budget, I stumbled on the ATS website, and I'm so glad I did! I contacted ATS to request advice and Nick promptly replied with a wealth of information, providing us with options and relevant contact details. I only wish I'd found them sooner!
Carol NortonCarol Norton
10:01 17 Mar 23
I've been so confused about how to achieve the look I'm after, and going round in circles with various window/door companies, trying to get away from the huge chunks of plastic currently around my windows. I didn't expect an email to a company found through a Google search to really help - but I was desperate, so I tried. I'm SO glad I did. Finally I have clear explanations from ATS of where I've been going wrong, exactly what I'm looking for, and a list of local companies that might be able to provide it! The response has excelled my expectations and I feel as if I'm finally inching closer to a home with which I'll be happy and comfortable: thank you.
David NunnDavid Nunn
20:54 14 Mar 23
It is rare that I write reviews, however after my very positive communication with Nick - enquiring about suitable slim sash aluminium windows for my project, I felt that a review was definitely warranted. I can reinforce the many positive reviews posted so far, Nick was very quick to respond, providing comprehensive detail, with excellent independent advice.In summary, great service, thank you Nick.
Chantal AuerbachChantal Auerbach
13:04 09 Mar 23
Nick from Aluminium Trade Supply was incredibly helpful informative and pleasant to deal with. He responded quickly to emails and was very knowledgeable. Highly recommend being in touch with Nick if you are considering new aluminium windows or doors.
Lee JonesLee Jones
20:21 22 Feb 23
I dropped Nick at Aluminium Trade Supply an email re high security slim sightline bi-folds and their alternatives and he responded that quickly (and so comprehensively) that I felt bad I’d not paid him for his time!Nick Sir your product knowledge is outstanding and you are providing a level of service that goes wayyyy above and beyond expectations. I’ll definitely make sure I mention Aluminium Trade Supply to anyone I encounter looking for a fenestration solution 🙏🏼
15:13 13 Feb 23
We are looking to replace some old UPVC patios doors with aluminium ones. The ATS website is a great source of advice in an area where clear information is sorely lacking. Having used the website, I then followed this up with a number of specific questions relating to our search, and Nick came back very quickly with clear, detailed and very useful advice.I have been very impressed with both the website and with Nick's advice. My only regret is that I didn't come across ATS before replacing various windows in 2021 - I'm sure it would have saved me a lot of grief and money! Thanks again Nick.
Azza McCabeAzza McCabe
17:47 01 Feb 23
So impressed with this company.Responded to my query quickly andgave valuable advice. Nick was extremely helpful and we were able to move forward with our project.
Adri LoloçiAdri Loloçi
11:21 08 Jan 23
Nick was super fast to respond and provided some great recommendations. I would recommend this website to anyone looking to find bifold or sliding aluminium doors.
Stephen HoustonStephen Houston
16:16 03 Jan 23
Looking for aluminium crittall style internal door and external patio French doors. Noted good reviews and thought would ask for advice. Comprehensive reply with excellent independent advice and lists of fitters who could provide products and installation. Great service.
Inga GeachInga Geach
08:25 21 Dec 22
Nick from Aluminium Trade Supply has been extremely helpful with navigating the jungle that is aluminium glazing for our upcoming extension project. His advice was prompt, detailed and always impartial. Very grateful for your input, thanks Nick!
Amanda BurtonAmanda Burton
10:54 16 Dec 22
Brilliant website and an excellent service. Nick provided not only detailed advice and supplier contacts, but highlighted the considerations of various products so I could make an informed choice. Our Sunvista minimal sliders were fitted this week and I couldn't be happier, stunning. Thanks once again for your advice and recommendations, invaluable!
Keith BarnesKeith Barnes
17:18 10 Dec 22
Very helpful advice given to my question, including the name of 3 different companies that i could try for the product being enquired about. Many thanks
Munim ChowdhuryMunim Chowdhury
11:45 13 Sep 22
Nick has been very helpful on signposting me to a number of partner organisations for steel/aluminium doors.
SUSAN wallaceSUSAN wallace
17:26 31 Aug 22
My experience with this firm was exceptionally good and this is notalways the case as a female, dipping a toe into technical waters.I was spoken too with courtesy and at a level that helped me consolidate what was needed .On top of that I was given a list of companies and places where I could obtain the type of product I needed.I could not thank them enough and would certainly go there again and reccommend others do too.
Paul SalterPaul Salter
22:39 22 Aug 22
Contacting Aluminium Trade Supply is like contacting the Oracle direct. Advice is always comprehensive and balanced. On multiple occasions they have provided me with options that fully meet our objectives. Many thanks.
Nick McCormackNick McCormack
20:25 14 Aug 22
Really helpful and useful came back to me on a Sunday with some invaluable information. Highly recommended.
ray addisonray addison
13:14 14 Aug 22
received a prompt reply to my query,and helpful information from ATS