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Glass extensions for terraced homes: FAQs

17 February 2021
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Adding a side return extension is one of the best ways of increasing and improving the quality of family space in terraced and semi-detached houses. Here are answers to common FAQs to help you take the next step in transforming your home.

WHAT is a side return extension?

A side return extension is typically carried out in the kitchen area at the back of the house. The side return – the pathway that runs alongside the ground floor of your home – makes the perfect space on which to build the extension. Hence the name side return extensions.

Finish a side extension with glass roof panels and glass walling, sliding or bifold doors and you’ll not only enjoy a bigger kitchen, but a brighter, lighter open plan living space. Designed thoughtfully, glazed side return extensions bring welcome natural daylight with no loss of privacy.

Glazed side return extension

What type of glass structure is best?

Our recommendation is to go for an all-glass insulated or thermally broken aluminium frame extension. They are robust, high-performance structures with slim sightlines, thermally efficient and offering huge glass panes to maximise your natural light and sense of outside space.

Side return extension interior with glass roof for south london home

Glazed roof panels will flood your new space with light, but an opening roof light is a great option for the roof if privacy from neighbours is more of an issue. There are a number of models available that’ll automatically open and close according to the temperature, so you can ensure you’ll always have a perfectly-ventilated space.

This architect’s own side return extension design has solar control glass, an advanced glazing option to reduce the amount of UV rays entering a glazed extended living space, adding both comfort and peace of mind about potential fade damage to furnishings.

Are FOLDING or SLIDING DOORS best for a kitchen extension?

The choice between sliding doors and folding doors is often a matter of how large the opening to the outside space is.

Sliding doors open by sliding one or more of the panes of glass behind another. In this kitchen-dining project, glass walls are created by a combination of fixed and sliding panels, meeting at an opening glass corner. The ODC SL320 system chosen here has minimal frame visibility, and this installation’s bespoke panels vary in width to align with the extension’s structural elements.

Opened corner sliding doors reveal design

Bifold doors open in a concertina motion in which the panels fold together. Bifold doors can run on one track, whereas the sliding doors will always have at least two. This won’t bother everyone, but it does affect the aesthetic and final look. Bifold doors work very well for smaller spaces, as they allow for nearly the whole set of panes to be opened up in the summer months.

Managing Director of ODC, Tim Hedges, explains:

“As a rule, we find that where the opening to the outside space is not particularly large, our customers tend to choose bifold, or folding doors, as this means that they benefit from being able to have the whole space open to the garden. Where the opening is larger, we are seeing more people opt for sliding doors as, for them, it matters less than one-third, or perhaps even half the space, will still be a glass panel.

Sliding doors will have a much less visible profile when closed, which some customers think adds more ‘wow factor’.  For example, we have just finished an installation of sliding doors where our client’s house has a stunning view onto Poole Harbour. The choice of sliding doors in this case was absolutely the right one. In terms of visuals, both options look great, but many customers still prefer the minimal look of well-designed pair of sliding doors.”

Bifold doors for modern kitchen
A single traffic door within system allows easy access to the garden on days when it’s too cool to fully open bifold doors

Can my side return extension use the existing access to the garden?

Yes, of course, and here is the perfect illustration of how a side return extension can add living space and natural light and still retain a connection to the original French doors to the garden. This design by FINE Architecture in Dulwich is a triumph. Instead of sliding doors or bifolds, it features a large fixed picture window and inside there’s a charming window seat.


Side return extension for South London home

Does a glass ground floor extension require much structural work?

Typically major works needed for this kind of extension include:

  • Build a new wall on the boundary between your land and your neighbour’s, on the kitchen side. This will require consultation with the owner of your
    neighbouring property. The wall might have to be installed solely on your side.
  • Add a new roof to the extension area. Many people go with a fully glazed roof or a skylight in order to create a brighter kitchen.
  • Knock through the sidewall of the current rear room.
  • Install a new floor to integrate the existing and new extended area.


Council rules for this kind of project actually changed back in 2008, so from 2017 planning permission is not required. This applies as long as the extension is only on the ground floor and doesn’t go any higher than four metres.

It also can’t be any wider than half the width of your house’s size before the build starts. It’s worth noting that even though it’s fairly likely you won’t need planning permission, there will be building regulations you’ll need to comply with.

It’s important to consult with your project manager and contractor on these issues.

HOW LONG WILL it take to install a Glass EXTENSION?

For a fairly standard project, it’ll tend to take somewhere between eight and ten weeks for the structural work. Plus, of course, the time for finishing and decorating the new interior.

Our top tip for a successful glass extension

If you’re embarking on a home extension project, Tim advises,“It is key to plan the glazing elements of your project early. High-quality glazing is a considerable investment and you have to get it right.”

Customer Projects

Looking for inspiration? Explore glass extensions designed for previous customers on our Projects Page, including a delightful glass extension for a London terraced house.

Why not work with a professional experienced team who know what it takes to achieve great results? Read more about the ODC team here and if you’d like any guidance on glazing design for your project, please give us a call on 03300 586 792 or complete our contact form today. We’ll be delighted to help.