Supply only vs supply and fit, which is better?

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Nick Dardalis

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For property renovation projects, homeowners look to save money, and the supply only vs supply and fit route for the windows and doors is one consideration. The supply only route is great for saving money but does not always offer full guarantees and product support, nor does it always provide longer-term peace of mind. On the other hand, the supply and fit route is a complete service, taking care of surveying and installation, product support and aftercare, and usually provides a clearer guarantee period, not to mention the benefits of working with a FENSA or CERTASS-approved installer. This article covers all the pros and cons of supply only vs supply and fit to help you make the best decision for your property project.

Supply only vs supply and fit when buying new windows and doors

lady double glazing installer measuring an open white window explaining supply only vs supply and fit article
If chosen right, both builders and window installers can offer a good service.

You trust your builder to construct a new home and extension, confident that your roof and walls won’t cave in. So why can’t you trust your builder also to fit your windows and doors? The reality is many builders are perfectly capable of window and door installation, and just like window installers that are suitably qualified, they too can carry out a professional installation. With builders able to fit windows and doors, considering the supply only vs supply and fit route for the glazing is worth considering.

Our consistent advice with modern aluminium windows and doors is that there is no bad product on the market. Many bad experiences with new windows and doors are down to the quality of the manufactured product and more importantly, the quality of the installation. A correct installation is probably the most important factor to ensure the long-term performance of your new windows and doors.

The supply only service explained

As the name suggests, the supply only service is the window manufacturer or supplier, such as a trade counter or other provider, only providing the windows and doors. No installation is provided, and it is assumed you will make your own provisions for installation. The supply only providers of windows and doors all have different criteria for how they will handle your order and with the vast majority, you take all the risk.

Supply-only windows and doors usually involve you being responsible for giving them the information a professional window and door survey would ascertain. Some of these include:

  • Giving your supplier the precise manufacturing sizes.
  • Determining which exact frame types are required to suit your existing or new openings.
  • Advising of any egress hinges to meet Building Regulations.
  • Determining the sizes and types of cills, trims, frame add-ons and other ancillaries.

Some supply only companies will help you with instructions, survey guides, and other information to help you ensure they provide the windows and doors you need. However, you must remember that the vast majority of supply-only window and door providers are set up to receive clean and prepared orders ready to manufacture. Not all are able or willing to hand-hold you.

Depending on your chosen supplier, delivery charges may be extra, and the quality of the installation instructions varies from provider to provider. Some providers expect you/your builder to provide the fixing screws, straps, silicones and other accessories that may be needed to fit the windows and doors. It is also unlikely the supply only route will give you access to other aluminium products such as corner trims or covers, frequently required colour matched to the windows and doors.

The obvious benefit to the supply only service is a reduced cost compared to the full supply and installation route. With many professional installation companies quoting 8-16 weeks installation lead times, the supply-only route certainly helps if your project is on a tight schedule.

Whilst some excellent businesses are set up to provide a smooth and reliable supply only service, and we can certainly put you in touch with these, these companies are largely set up to manufacture and supply clean orders and are not set up to provide the white glove service of professional installers.

By far, the biggest risk in choosing supply only vs supply and fit is that you bear the most responsibility. When an installation does not go as planned, the supply company will often blame the installer, and the installer will blame the supplier.

Supply only pros

You save money

Faster Lead times

Not recommended for complex installations

Beneficial with a reputable company

Supply only cons

Greater risk should things go wrong

A reduced product guarantee

Fewer options such as designs and colours

Less clarity on product brand or system

Many products need trained glaziers and fitters

You are responsible for certifying the installation

Limited access to showrooms or one-to-one advice

The supply and fix service explained.

The supply and fix route provides significantly more benefits, with the most trouble-free experience and complete service, leaving you with far less to organise. Professional window companies offer you access to their showrooms, face-to-face advice, more time, and access to more personalisation options such as more colour choices, more handle styles, glass upgrades and other accessories, which the supply-only route tends to restrict.

The crucial survey is taken care of by a professional surveyor, more familiar than a builder with the specific window brand, its various configurations options and how it needs to be designed for your particular opening. Crucially, the supply and install route remains the best for getting a flush or low threshold because this type of installation needs collaboration between the door provider and the builder. All aspects of the installation are taken care of, and you have the peace of mind your installer is experienced and has fitted the specific window or door brand many times before.

Even if your installer does not manufacture the products and uses a trade supplier and manufacturer, they have a better experience and far longer trading relationship with that supplier should things go wrong than you will, buying once via the supply only route. Study the terms and conditions of those companies offering a supply only service, and you will invariably see a clause stating they are not responsible in any way for the installation.

Supply only vs supply and fit product guarantees

We are routinely asked about the supply only route for windows and doors by homeowners wishing to save money. However, many homeowners are rarely aware of the vastly reduced product guarantees they get with supply only vs supply and fit. The product guarantees do, of course, vary from company to company and depend on the products themselves, but generally speaking, the following applies when comparing supply-only guarantees to the full installation service.

Supply only guarantees

The whole product guarantee is vague

Glass & components, typically 2-5 years

Builders rarely offer any installation guarantee

Little support long term

Reduced access to parts and spares

Supply and Fit Guarantees

Typically ten years on the whole product with fewer exclusions

Glass & components fully covered unless specifically excluded

Your product installation is covered

Some 20 year guarantees when fitted by approved installers

Better support when products are out of warranty

If your project is for a home you are likely to sell, then the product guarantees may matter less, as many installers stipulate that their warranties are not transferrable to the new property owner. However, if you are investing in a long-term home, the supply and fit route provides the best peace of mind.

The guarantee you get very much depends on the supplier, and when comparing supply only vs supply and fit, do your research and establish from your chosen supplier what guarantee they offer and how that relates to their products being fitted by others. The terms and conditions can be complex to get your head around, so do ask questions and get information in writing.

In the unlikely event of significant issues with the product and its installation, the supply only route can be more restricted in getting problems solved. The supply and installation route is better, with you more likely to get responses from all parties in the supply chain and involve them as required to help solve your problem. This is because the supply chain is more transparent, and the installer is known to the design or manufacturing company, trained, approved and supported.

Where supply only is not recommended

slimline curtain wallingfloor-to-ceiling glazing on supply only vs supply and fit article
Large sliding doors and complex designs are not recommended supply only.

Aluminium doors and windows are highly-engineered products. There are many reasons why the best brands of doors and windows offering outstanding products and excellent customer service choose a business model based on approved, trained and supported installers and never provide their products supply only.

When comparing supply only vs supply and fit, glazed screens, complex designs, specific functionality or for ultra-slim bonded sliding doors such as Cortizo, we advise avoiding the supply only route. Certain products demand an installation by qualified fitters familiar with the product and aware of exactly what must be done to ensure a long-term reliable product. Some products are more forgiving if the opening is not quite square or they are not 100% level. Other products demand more precision and must be fitted exactly as designed and intended by experts. If your extension has bifolding or sliding doors with a gable or shaped head above, measuring for this often requires a template, and some supply only companies won’t carry out this work, and some may not even provide glass. A professional surveyor can handle shapes, curves, bay windows and other non-standard shapes easier and better than dealing with a supply-only company. The more complex your design, the more features and functions you want from your glazing, the more likely you will achieve it via the supply and fix route.

The other consideration is site safety and the correct handling of your new windows and doors. With large sliding doors, whether moving them to site or handling their glass, professional installers rely on the right equipment and trained staff. This equipment ensures less stress on the product, reduces damage to the paint finish and gives you the confidence of a product fitted by professionals that know what they are doing.

Your builder may know how to fit windows and doors, but that knowledge does not extend to every product. You risk all manner of problems choosing the supply only route for windows and doors designed with the full service in mind. Therefore, the experience you get supply only vs supply and fit does depend on the product you intend to buy.

Finding window and door fitters

So you’ve decided to buy using the supply only route and now need to find a fitter. There are companies and individuals offering installation services and you can get in touch with us for details of these. However, these can be limited and specific in the products they choose to install.

You are unlikely to find ‘general’ window fitters easily because, as we’ve explained, fitters like using products from suppliers they know and trust. Some popular brands like Smart Systems are widely available from numerous suppliers, but they are not provided in exactly the same way. Fitters are aware of this and do not want the hassle of having to deal with products provided differently from what they are used to.

For the same reason, your local window companies are also unwilling to provide an installation-only service for products they do not supply. Another reason why the supply and installation route provides an all-round smoother and easier experience.

You can consider doing an online search for double glazing repair and maintenance companies as some of these do offer an installation service, or look to find smaller installers, offering this service.

Therefore, when considering supply only vs supply and fit, think about how easy it will actually be to find the installer you are looking for in your area. An installation company will unlikely want to travel a larger distance just to fit one patio door. Similarly, an installer may stipulate to you how they expect to receive the products in order to fit them.

Registering your installation

You will need to ask your chosen installer whether they are FENSA or CERTASS certified. Registered installers can carry out the self-certification required for building regulations and give the paperwork required should you need to sell your home. If you are getting your builder to fit the windows or carrying out a DIY installation you will need to request an application for approval under Building Regulations from your local council. This can take from a few weeks to a few months.

Window and door installers are not required by law to be registered with FENSA or CERTASS, but you cannot install windows and doors without building regulation approval. If you plan on selling or remortgaging, having the required paperwork is much easier and speeds up the process.

You may that for supply only vs supply and fit that the installation route via a FENSA or CERTASS-approved installer is simpler and you cannot self-certify your own work.

Supply only vs supply and fit – summary and conclusion

Whilst the supply only route offers cost savings, there are several compromises with this service, the most important being registering your installation and understanding the product guarantee both from the supplier, your builder or your chosen installer. That said, the experience you get very much depends on the company you choose and plenty offer a reliable service, have excellent reviews and have the processes in place to make buying windows and doors supply only easier.

Do bear in mind that some companies offering buy-direct windows and doors rebrand their products, and you may find it hard to establish what these are. In most cases, these rebranded doors and windows are the same systems available from other suppliers. A reputable company should have no issue whatsoever telling you what system they manufacture and supply. If you’d like further information about a supplier you’ve come across and would like to know what system they offer, you can contact us, and we can tell you. If you wish, we can also suggest comparable products, so you get more choices.

The supply and installation route will always cost more, but you get a complete service, better product choices and aftercare, and we recommend this as the better option. Supply and installation are crucial for large or bonded patio doors, glazed screens, more complex systems and where you have specific design requirements such as a low bifolding or sliding door track. You also have access to a better overall buying experience being able to view products, take your time, ask questions and explore products in real-world environments, compared to online.

You can contact us for companies offering supply only or supply and fit windows and doors and we can help you with choosing the best products for your project from the right suppliers.

Providing expert help to homeowners and trade professionals since 2010




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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