Sliding doors: the ultimate guide to home glazing and glass walls

When Ian Stewart built his ideal home for retirement, he had one priority: a water view. Stewart, 61, who ran his own photocopy software business, bought a plot of land at the mouth of the River Hamble, on the Hampshire coast near Southampton, and in 2021 built a five-bedroom house with an open-plan kitchen/living room overlooking the river through a wall of glass.
He didn’t want bifold doors, as the multiple frames obstruct the view. So he paid £40,000 for four sliding panes that are each 3m wide, with slender aluminium frames by Ultraline that are only 20mm wide. “We went to the Homebuilding & Renovating show, where you can try out doors and talk to companies. We tested the weight of the sliding doors, because as we get older it’s important that we’re able to open and close them. We felt [the Ultraline] had the best sliding action; you can open them with one hand.”
Unlike most building projects, installing the glazing went smoothly. “Minima, the installers, were meticulous.” And the end result has changed his life. “It’s lovely having all that glass. The thin frames mean you’ve got no distortion of the view, and on horrible days you see the weather coming in and rain lashing the window, but you feel snug inside, there’s no leaks or whistling wind. And in the summer you just open it all up, so it feels like you’re sitting outside.”
Not everyone has been so lucky. When John Ayris and Anne Spratling renovated an 1830s farmhouse in Kent, they installed a 9m span of glass with sliding doors, paying £120,000 to an English company, rather than splashing out £250,000 on a German one. But their installation caused two years of delays, and the company went bust, leaving them high and dry. “They didn’t measure properly and made the doors bigger than the track,” Spratling says. “The doors weren’t able to link tightly together so weren’t draught-proof. It was difficult to slide the doors along.”
Ask a homeowner what the biggest challenge of their renovation was and they’ll inevitably say the windows — the big sliding ones and large walls of glazing that are now so popular. But it’s not as simple as just paying more for German windows, according to the architect Andy Ramus, head of AR Design Studio near Winchester. “The big problem with the industry is there’s so many people involved in the supply chain.” There are designers who create window systems, as well as manufacturers and installers. “Along that journey all kinds of things can go wrong,” Ramus says.
“You can get a good German system, which can be shipped out to 500 different manufacturers, some of which are excellent, some of which are poor,” explains Dan Smith, the founder of Minima Windows. “And then you can get 500 different installers, some good, some terrible, buying that product. So you can have Mr and Mrs Jones who bought the same German door as Mr and Mrs Smith. One has an amazing experience, one has a terrible experience.”
The ideal would be to use a company that designs, manufactures and installs its own systems, says Smith, but this is rare — Maxlight, a British company, is one. He also cites Sky-Frame, a premium brand that is designed and manufactured in Switzerland, and uses a mix of its own installers and approved installers. If you can’t find an all-in-one outfit, Smith recommends reducing the number of companies in the supply chain to two, rather than three, to reduce risk.
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Ian Doble, a homeowner near Swansea, used sliding doors by Internorm, which designs and manufactures systems in Austria, and uses approved UK installers. “Their customer service is exceptional and the windows are so easy to open.”
To keep it simple, Smith’s company, Minima, which has offices in London, Kent and Wiltshire, installs only one system — sliding windows and fixed glazing by Ultraline, which manufactures in the West Midlands and uses only two approved installers in the UK.
The key is choosing your installer carefully, Smith says. The biggest problems arise from windows that are measured and fitted incorrectly. Minima visits the site at least three times before installation: for an initial survey (to inspect ease of access and discuss with builders how to prepare the opening); a proper survey (measurements of the opening after the hole is made); and a preinstallation check to avoid surprises on the day of installation. “If the measurement is 10-20mm out, that could be £20,000 worth of doors that are useless,” Smith says.
Many companies don’t bother with a preinstallation check and do surveys before the opening has been cut, leaving a load of TBCs, causing drama on the day of installation. “The base that the doors rest on is often too low by say 30mm, which means lots of packers are needed underneath the doors, which then don’t slide properly,” Smith says. “They creak.”
What precautions should homeowners take? Insist on inspecting one to three previous installations that the company has done, and not in a showroom. Try opening, closing and locking the windows. And ask the homeowners how detailed the survey process was and what paperwork they received.
Installers need to meet your builder in advance. “Make sure the window company and builders are 100 per cent clear on what is required for the perfect installation,” Smith says. “You wouldn’t believe how often this doesn’t get done. The builder will have his own preferred supplier, because he usually gets a financial kickback from them. So often builders are miffed if the customer chooses their own supplier and washes his hands of them.”
Ramus, meanwhile, gets miffed by bifolds, as they often twist and jam in the track; he won’t use them. He only uses Ultraline/Minima and Maxlight glazing on his projects. He spent £60,000 on 50 sq m of Ultraline glazing for his own extension. “The mechanics are beautifully engineered. It’s got eight wheels per pane. Cheaper ones might have only four wheels, and the lady of the house might struggle to open it. Whereas mine, they almost roll open.”
Ramus says it’s not worth scrimping and saving on windows, as cheap and cheerful frames are more likely to bend with big sheets of glass. It pays to splash out. “A big sheet of glass is going to give you views, light and ventilation, and if you want to open and close it a lot it’s got to be easy to use and not break. People quite happily spend £100,000 on a kitchen, but what are you really getting for that much money that you couldn’t get for £30,000 or £40,000? If you spend a bit more on glazing, you get better sightlines and usability. There’s nothing worse than enduring a 12-month build and then having another two years chasing people because it doesn’t work.”
1. Limit the number of panels that open to save money, reduce complications and minimise the number of unsightly tracks required.2. To prevent overheating, use solar-coated or solar control glass. Triple glazing adds a lot of weight, which means it makes openings smaller, and isn’t significantly better at reducing heat.3. To reduce summer heat, consider external Venetian or roller blinds or awnings. Place blinds on the outside as internal blinds collect heat on the inside of the glass, acting like a radiator. Or build a 1.5 metre roof overhang.4. The best glazing still loses five to eight times more energy than a solid wall. Consider framing selected views instead. 5. Aim for low U-values (the amount of energy that the system lets through). The ideal is between 0.6-0.8W/m²K. Standard glazing is around 1.4W/m²K.6. If an installer gets multiple bad reviews online, even among good ones, that’s a red flag. 7. Look up the installer on Companies House: it’s a red flag if the director has folded or dissolved companies. You could lose your deposit.8. Try to find an installer with in-house staff installers. Subcontractors are transient, less motivated and less accountable. 9. Check if the installer has an insurance-backed warranty. 10. Check if the firm has a real showroom or office. Some have a lovely website but operate out of a bedroom. 11. Choose the installer through word of mouth. Look at planning applications in your area that have been built, knock on the door and ask about their windows. The National Self Build and Renovation Centre has a network of self-builders you can ask.12. The installer should only do the survey after the window openings are cut. Ask whether they also do a preinstall check.13. Many trickle vents look ugly. Integrated ones look better (Velfac and Internorm offer these). Or get windows you can lock slightly ajar (2mm) for ventilation. Or install a mechanical ventilation with heat recovery system (MVHR) so you won’t need trickle vents.14. Consider self-cleaning glass — helpful for hard-to-reach areas.
We surveyed architects for their preferred window systems (do your due diligence on installers). These are the brands that came up most frequently:
• Sky-Frame: recommended by Eldridge London, Paul Archer Design, Finkernagel Ross, Gregory Phillips, Meme Architects, Carmody Groarke• Schueco: Sophie Bates, R2 Studio, L&C, Meme, Square Feet Architects• Cantifix: Square Feet, Alison Brooks, Loyn & Co, Paul Archer, Finkernagel Ross• Maxlight: Paul Archer, AR Design Studio, Eldridge London, Will Gamble, Square Feet• Ultraline: AR, Philip Wadge Architecture, Bindloss Dawes, Tidal Architects• Internorm: L&C, Orme Architecture, EL Design Studio, MA Architecture• Cortizo: R2 Studio, EL, L&G, MA• Velfac: R2, MH Workshop, Tonkin Liu, Berkeley Place
The next London Homebuilding & Renovating Show is September 27-29 at Excel. Get free tickets at homebuildingshow.co.uk/pr-the-times