Guide to choosing internal doors

With aluminium internal doors enjoying significant growth and plenty of new or innovative products on the market, our guide to choosing internal doors tells you what to look for and explains why buying internal doors is, in many ways, easier than buying external replacement aluminium windows and doors.

Choosing internal doors – what are they?

choosing internal doors showing aluminium internal doors dividing lounge and bedroom area in a loft
A wide variety of products now provide many options when choosing internal doors

Modern styling, colours and reduced sightlines are very much a feature of modern aluminium doors and windows. As well as this, there’s the growing desire for steel look, heritage, Art-Deco and Scandi style glazing. All these styling and product requirements now come to internal doors. In short, homeowners are now looking to add the same look inside the property. Window and door manufacturers and installers are seeing new sales opportunities, providing internal doors as part of a project or in addition to previous work carried out.

Other pages In this section

Internal Doors and Screens

When choosing aluminium internal doors, therefore, you’re looking at new products specifically designed for internal doorways, such as room dividers, partitions or feature screens with or without doors.

What doors are best when choosing internal doors?

Finding the best internal doors depends on many factors, not just styling. Materials matter as they provide different aesthetics, texture and function. We’ve put together some of the best brands in both glass and aluminium doors to help you choose and provide a starting point.

Consider how you’ll use the doors both open and closed. Replacing an old wood door to a room is simpler than deciding on a product to act both as a room divider and a focal feature. For larger openings would you prefer a full set of larger double doors or smaller modules with matching side panels?

Then it’s worth thinking about whether a full framed product or all glass version works best in your home. Both promise quality, long service life and timeless looks.

As you do your research around internal doors the following products are available. Most of these are available with matching side and top panels, opening options, glass, colour and handle choices.

  • Hinged single and double doors
  • Sliding doors also going into a wall-pocket if needed
  • Slide and stack doors
  • Pivot Doors
  • Folding Doors

Are aluminium internal doors any good?

Whether frameless with minimal aluminium or fully framed, when choosing internal doors, aluminium gives you all the well-known benefits of their external siblings. Choose aluminium and you get these exclusive features:

  • Slimmer sightlines than other materials, only steel is slimmer
  • The ability to match internal and external glazing
  • Bigger door sizes than other materials
  • Substantial choice of colours

Why you should use external aluminium doors inside

smart systems aluspace room divider in a new build house
An exterior grade Smart Systems Heritage product used internally

It’s not unusual for good glazing firms to offer the same doors you’d have outside as internal doors. And for some products like internal bifolding doors, some sliding doors, single or French doors, it is the only option available without going to bespoke made and very expensive products. There are also installers that prefer to use the same exterior systems inside for their own business reasons.

When choosing internal doors and looking at the exterior products, you will get some features you might not need. First of all are profiles with thermal insulation, something you won’t need inside. You’ll probably also get the full set of weather seals, brushes, gaskets etc used on outside doors for weather protection – again not essential inside. Double glazed units are another. You’re likely to get the same multi-point locking handles, again not essential inside.

If you want the acoustic benefits of double glass vs single then these exterior products are fine. The added weather sealing also helps keep the doors tighter. The additional locking points aren’t a problem for most users either, with many never locking the doors.

A good installer can help you choose doors with suitable glass, give you the lock and handle options available and even provide hinged doors without any visible threshold. All bifolding and sliding door products can be fitted with a flush track. Our advice here is don’t discount these doors and compare them with their internal counterparts where they exist.

Aluminium vs steel doors. Which is better?

picture of slim steel crittall style screen dividing an office space
Only genuine steel products like Crittall® or bespoke made, give the 100% authentic steel look.

Especially for fully glazed doors and those in the steel look, it’s common to compare the two materials. Whilst you’re getting some similar styling, you’re not getting exactly the same product.

Be careful of terminologies such as Crittall® Look, Crittall Style or Crittall Replacement when choosing internal doors. Only the genuine steel brand or product gives you the look, the style and like-for-like replacement.

Choose an internal door such as the Innervision system in steel, and the differences compared to a similar aluminium product by Aluco, Aluspace or the new Origin OI30 product are obvious.

Steel doors are noticeably slimmer compared to aluminium. When comparing aluminium vs steel doors, you’ll also notice a fully welded construction even with the glazing bars. Aluminium by its very nature is mechanically joined everywhere. So whilst an expert manufacturer will provide a crafted product, visible joints in aluminium are inevitable. You get seamless joints with steel.

Make no mistake, the current range of aluminium products designed in the steel style is excellent as is the styling. However, steel remains the luxury offering, it’s significantly more expensive than aluminium, but also more authentic.

Budget will invariably influence your choice of aluminium or steel for internal doors.

Important technical aspects when choosing internal doors

aluminium grey door inside modern apartment building
Doors in public buildings must meet specific Building Regulations for accessibility and use.

Depending on their location and use, do make sure when choosing internal doors, you’re complying with certain Building Regulations. These can include:

General Safety

There are specific standards regarding glass in doors and nearby areas. Glass in all doors must be toughened or laminated and including side panels and adjacent glazing.

Fire Safety

Where Building Regulations stipulate internal doors with fire protection, you can only have steel. Aluminium has no fire rating. The fire rating depends on whether the doors are on an escape route or form part of building compartmentalisation. Fire doors comprise special glass, sealants, strips and hardware. Never compromise on fire safety.

There are some online websites selling internal doors with a fire rating. Yet, they cover themselves very well, potentially leaving the end-user exposed. They say, that the door is supplied without an FD30 assessment and the customer assumes the responsibility to check with Building Regulations if the door’s characteristics are fulfilling their requirements.

If you need a door with a 30 minute, 60 minute or more fire rating, our recommendation is you don’t buy online and instead go to a professional retailer. And do bear in mind many of these doors are aluminium doors with nothing but fire glass. There are no smoke seals, intumescent strips, suitable fixings and other absolutely essential components that’ll save a life in the event of a fire.

Our advice is broad-based and general only – always consult a professional.


If your internal doors need to contribute to the overall building ventilation, air gaps may be required. Again this is something Building Regulations can advise on for your particular project.

Energy Efficiency

In some circumstances, where internal doors sit between heated and unheated areas (such as a garage), you may need to meet specific U-Values.

Doors in public buildings

If you’re choosing internal or external doors in a conversion to flats, or where doors form part of the main entrance or to a floor, doors must meet the requirements of BS8300 and other standards relating to access to and the use of buildings. This includes doors meeting accessibility requirements and other required functions. Check with your local authority.

Internal doors separating a conservatory

Remember when fitting doors to separate a conservatory that Building Regulations apply. The doors have to comply with Part L of the Building Regulations even though the glazed extension or conservatory won’t.

In these instances, a CERTASS or FENSA registered installer is required.

Quality and specifications with internal doors

steel-look interior doors between a kitchen and lounge
Internal doors come with similar high specifications to external doors

Whilst you don’t need to check out performance credentials such as weather protection or external security, it helps to explain what you can expect as a minimum when choosing internal doors.

The good news is, that much of the core component quality you get with exterior glazing is also available internally. This covers aluminium profile quality, the paint finish, hardware quality and the glass.

Aluminium profiles on internal doors

You can expect the same high aluminium profile quality across all products, so there’s no need to pay a huge amount of notice to products marketing ‘premium-grade’ or similar messaging.

All quality systems use the same grade of aluminium, typically extrusions to BS EN 755-9 and BS EN 12020 from 6063 T6 aluminium quality. This grade is for architectural applications, designed with tighter tolerances and has stricter quality control regarding the visible surfaces.

The powder coated finish on internal aluminium doors

Choose a product from one of the major systems and most of these have their own in-house coating plants. Where they don’t, they’ll use highly professional businesses specialising in the powder coating of aluminium. They’ll also be approved and certified as well as members of some of the leading coating quality organisations.

Therefore you can expect professional quality colour application similar, if not the same as, exterior grade glazing and with similar guarantees.

The glass used in your internal doors

Many glass suppliers are either substantial glass processing businesses or long established companies. Glass is subject to strict standards and quality control so you can expect a quality product every time.

Handles and Hardware when choosing internal doors

None of the brands you see for doors unless, they make a bespoke and highly individual product, make their own hardware such as locks, handles and components. All of them will source their handles from suppliers of high quality door furniture and other accessories.

Here you’re again buying products with quality-made components, often meeting their own set of stringent industry standards relating to locks, handles, their coatings, fixings and overall specifications. Your chosen installer will invariably offer the handle range available from their system company or supplier. Some may have the added expertise to

Guarantees you can expect buying internal doors

internal glass door between a bedroom and ensuite with frosted glass
The guarantees available when choosing internal doors vary widely by material and type.

The guarantee you can expect to get on your doors very much depends on the brand, who supplies them and the installer.

Many installers will offer the same ten year guarantee, others only provide five years, some only two. Some will provide manufacturer guarantees, others will simply carry forward whatever warranty comes from the colour coating or glass.

Fully glazed and frameless doors use glass and components from the major suppliers, therefore the warranty you get varies widely.

With varying guarantees available from supplier to supplier, so make sure you get a clear explanation for the entire product, not just the individual elements.

Buying and choosing internal doors online

It’s now easy to find glass, steel-look and industrial style internal doors online. There’s nothing wrong with buying online as long as you know exactly what you’re buying. Before you commit, it’s worth asking your supplier or making sure that you’re actually getting what’s being sold.

Many of the images used for these internal doors are computer generated images. Look at the pictures and compare them with the description. We’ve found several websites where their image shows doors too slim to be true, with no visible hinges and handles that, in some cases, aren’t even possible with that style of door. Then we see pictures of doors with three hinges per side, yet the descriptions state you get two.

Many of these doors are actually pieces of glass with black metal channel pieces applied to the edges and bars stuck to the glass. If you’re happy with this design that’s great, but do bear in mind these are doors with no system company behind the brand, or any brand at all for that matter.

Instead, glass is bought from one supplier, trims from another, hardware from another and a factory puts them together. It’s unlikely you’ll get the certified and professionally applied colour finish and do make absolutely sure the glass is toughened or laminated with the appropriate quality mark visible.

As we say, many customers are perfectly happy with this purchase, if you’re happy to get a significantly inferior product to those designed, tested and bought to market by proper systems companies or independent companies willing to stand behind their product because they design, make, fit and guarantee it.

If you come across such websites, do get in touch if you need more information on these products.

Choosing internal doors – tips and advice

slide and turn aluminium internal doors separating a dining room and kitchen

The choice of internal doors is substantial, covering all glass, doors with a bare minimum of visible metal, steel-look and fully framed products.

We’ve not covered styling in this article as the bespoke nature of these products gives you virtually unlimited options. Doors open in or out, slide or fold, stack together, even slide into a wall.

  • Remember to adhere to any applicable Building Regulations
  • Ensure you get clear information on the warranty provided
  • All products meet similar quality specifications for aluminium, glass, hardware and colour finish
  • Explore all types of products that’ll give the required look and functionality
  • Don’t discount exterior-grade products offered as internal doors

Assuming internal doors meet your budget, you can choose your doors based on styling, features, options and of course, confidence in your chosen supplier or installer.

Providers of these doors vary. Our advice is to go with those with clear expertise in aluminium windows and doors generally. It’s also fine to go with a smaller expert company, designing, making, fitting and guaranteeing their own products. Or you can get in touch with us for more information, product options and where to buy.

Providing expert help to homeowners and trade professionals since 2010




Get Free help finding the right products from the best suppliers

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