5 Issues No One Ever Tells You About When Using Sliding Doors for Your Extension — Including How Heavy They Can Be to Operate

For a long time, it was bifold doors that held court in the world of patio doors, wowing people with their ability to open up entire walls to the outside thanks to their clever concertina action. Then things began to change. Some heralded it as the death of the bifold, criticizing them, primarily, for their chunky frames. While I wouldn't go so far as to say they are done for (I happen to love my own set), there has certainly been a shift away from them, with architects and homeowners favoring a more minimalist look — and what is replacing them? Sliding doors, of course.

Sliding doors just have so much going for them, particularly those with super-sleek slimline frames that offer near-uninterrupted views. Then there is the fact that a totally seamless link can be created between inside and out through the use of flush thresholds, and that is before we even get into the breathtaking, oversized panes that can be specified.

That said, for all their benefits, there are some drawbacks to sliding doors, and it is well worth familiarizing yourself with these before you install them into your own home. I asked two experts in the field what the most common issues are and how to overcome them, too.

1. Sliding Doors Don't Suit Narrow Openings Well

One of the main selling points of sliding doors is the vast widths their panels can be specified in — however, if you don't have the luxury of an entire wall to dedicate to them, or perhaps want something a little smaller to fit in with your kitchen extension ideas, they might not be such a great option, as Rebecca Clayton, a director at IQ Glass, explains.

"Sliding doors are just not well suited to narrow openings. As a rule of thumb, the width of each sliding leaf should be at least one third of its height. When the ratio becomes too tall and slender, the pane can judder along the track, compromising the smooth sliding action expected in high‑end installations," says Rebecca.

The solution? "Specify a system with a proven track record for handling ultra‑tall and narrow configurations," suggests Rebecca (who recommends IQ Glass' Keller minimal windows system). "Working with a specialist ensures that structural support, rollers and track technology are all appropriately matched to the design ambition."

Rebecca Clayton

Rebecca Clayton is communications director at IQ Glass. She has many years of experience with the company, who specialise in architectural glazing and installs some of the most pioneering architectural glass technology available today. 

2. You Can't fully Open Up an Entire Wall to Outside

One of the things people tend to love about bifold doors is that they can fold and slide away to leave large expanses of wall totally open, allowing interior spaces to become at one with the outside. And when comparing bifold doors vs sliding doors, with the latter, this is hard to achieve.

"Unlike bifold systems, standard sliding doors cannot clear the entire opening: at least one fixed pane will always remain in place," points out Rebecca Clayton. "For clients wanting a completely unobstructed transition from inside to outside, this can feel limiting, especially in entertainment spaces or locations where the architecture is designed to disappear."

However, there is a way around this: "Design the space to accommodate pocket sliding doors," Rebecca advises. "With this configuration, the sliding panes disappear into a hidden wall cavity, or move over the external façade, creating a fully open, column‑free aperture."

3. Structurally Bonded Systems Are Hard to Repair

Not all technical developments turn out to be a good thing, and according to Edward Stobart, an expert at IDSystems, the quest for ever slimmer frames has led to some glazing mistakes and issues homeowners need to be aware of when specifying doors.

“For most doors and windows, the double or triple-glazed units are secured using a glazing bead. This bead clips or attaches to the inside of the frame, keeping the glass in place — a process known as dry glazing," adds Edward. “As dry glazing makes the frame a little bulkier, some door manufacturers have opted to glue (or bond) the glass directly to the frame. This holds the pane in place and achieves the slim sightlines many homeowners want. These types of sliding doors are known as structurally bonded systems."

So what's the problem with these doors? “The use of permanent adhesive," says Edward. "Since the glass is bonded to all four sides of the frame, replacing it requires the entire sliding panel — the glass and the frame — to be removed and replaced as a single unit. We’ve spoken to a number of customers whose glass has shattered on their existing sliding door system who have been unable to get a replacement panel and have needed to order a completely new set of doors — even worse, while damaged glass panes may be covered on your home insurance, it is unlikely that a completely new set of doors will be."

Edward suggests the best option is to look at 'semi-bonded' doors instead. “Some ultra-slim sliding door systems (such as the EDGE2.0 from IDSystems) use a semi-bonded approach where the glass is bonded only at the interlock (where the panels meet) while the other three sides are secured with a glazing bead. It doesn’t compromise the view through the doors, offering central sightlines as slim as 20mm, and allows for just the glass to be removed and replaced if needed."

Edward Stobart

A long serving member of the IDSystems team, for the past 20 years Edward has advised and supported self-builders and renovators to identify the most suitable glazing options for their project. He has recently finished a complete renovation and remodel of his own home, transforming a tired 1960s house into a stylish modern family home.. His expertise ensures that each project is equipped with cutting-edge, bespoke glazing designs that enhance both functionality and aesthetics.

4. Oversized Sliding Doors Can Be an Effort to Open

Yes, oversized doors look stunning, remain one of the top architecture trends, offer far-reaching vistas, and allow for a copious amount of natural light to pour in, but have you stopped and considered how heavy they must be to open and close? You need to, according to Rebecca Clayton.

"One of the greatest advantages of sliding doors — the ability to create vast, sliding glass elevations — is also one of their challenges," she explains. "With some panels reaching up to 18m², the glass becomes extremely heavy. For some homeowners, particularly where children or guests will use the doors frequently, this can make manual operation feel demanding.

"There are several effective ways to address this to ensure sliding doors are easy to use for all. Firstly, an experienced glazing specialist can calculate exact panel weights and help specify the ideal size to ensure smooth manual operation.

"You should also test them out in person before buying," continues Rebecca. "Reputable companies should have multiple full‑size doors on display at their showroom at varying weights so clients can assess what feels comfortable in real use. Or, for the ultimate luxury experience, opt for a system with integrated automation. High‑quality motorized sliding doors provide effortless operation regardless of panel size, combining convenience with a refined architectural finish."

5. Poor Installation Can Ruin the Entire System

Arguably, this applies to all kinds of doors, bifolds, and French doors included, but in the case of sliding doors, particularly those with enormous panes of glass and complex operating systems, ensuring installation is spot on becomes more important than ever.

“With sliding doors, who makes and installs them matters just as much as which doors you choose," states Edward Stobart. "While sliding doors may all look very similar from pictures on a website or in a brochure, how they are put together, and the care that is put into the installation will make all the difference to the finished usability of the doors.

"Ideally, you want the same company to manufacture and install the doors — that way there’s no finger-pointing if something goes wrong," continues Edward. "Misalignment, locks not working, or poor operation can’t be blamed on someone else. How accurate the tolerances are, how well the corners are jointed, and the attention to detail in how doors are put together all make a difference to how the finished doors look and slide."

FAQs

Do Large Sliding Doors Cause Overheating?

Swathes of floor-to-ceiling glazing and near-frameless glass patio doors have almost become the norm when designing an extension, but all this glass can cause something of a greenhouse effect if not approached with care. The key, says Edward Stobart, is to choose the right type of glazing for your space.

"Opting for the wrong solar control coatings and ending up with rooms that overheat because of direct sunshine in summer could completely negate any benefit of building the space," warns Edward Stobart.

"With solar control glass, the coating applied to the surface has properties to both reflect the heat from inside your home back into the room as well as reflecting or absorbing the heat radiating from the sun back to the outside," explains Edward. "The benefit is the reduced need for cooling rooms in the summer months. Solar control has two forms: either a tinted glass that absorbs heat or a neutral glass which reflects heat, and these are measured as a Solar factor or G-value. Both types of glass will reduce the amount of light transmitted through the glass; however, a neutral glass will have a higher rate of transmittance."

If overheating is a concern, it is recommended that you avoid low-iron glass, although it is a great glazing option for north-facing extensions.

"By reducing the amount of iron within glass, it becomes much clearer and inherently will let through more light," explains Edward. "This makes it a popular option to use on elevations that do not get direct sunlight. However, it also lets through more energy from the sun, which is great on a sunny autumn day, but it can cause a greenhouse effect in the summer months."

Sliding doors are a significant investment, so make sure you explore all the options before taking the plunge. If you're leaning toward bifold doors for your project, it's also worth noting that there are problems with bifold doors as part of your considerations, too.

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