There’s a particular moment on every one of these projects. The old kitchen wall comes down, the bi-fold doors go in, and suddenly the back of the house doesn’t feel like the back of the house any more. It feels like the garden just walked in and made itself at home.
That’s the pull of an open-plan extension with bi-fold doors — it isn’t really about square footage. It’s about the light that reaches rooms that used to sit in shadow, and the sense that a family can cook, eat, and watch the kids play outside without a wall in the way. We’ve designed a good number of these across Newbury, Berkshire and Oxfordshire, and the brief is almost always the same: more light, more space, and a home that finally works the way the family actually lives.
Here’s what we’ve learned — from planning permission through to the finished glass.
Most homes built in the last century weren’t designed with the garden in mind. Kitchens were tucked at the back, small and separate, with a single door out. An open-plan extension with bi-fold doors rewrites that relationship entirely — instead of one small window onto the garden, you get a whole wall that folds away.
The effect is bigger than the extra square metres suggest. Rooms that used to feel cramped and dark suddenly borrow the garden’s light and space. Families stop eating in one room and relaxing in another, and start doing both in the same bright space, doors thrown open in summer, glass steaming gently in winter.
This is the question we get asked before almost anything else: do you need planning permission for a rear extension with bi-fold doors?
Often, no. Under current permitted development rules, a single-storey rear extension can extend up to 4 metres from the original rear wall on a detached house, or 3 metres on a semi-detached or terraced house, without needing full planning permission — provided it stays under 4 metres in height and uses materials similar to the existing house. Want to go deeper? A prior approval route allows single-storey rear extensions up to 8 metres on a detached house or 6 metres on other house types, though your local planning authority does need to be notified.
Bi-fold doors themselves don’t usually change this — it’s the extension’s depth, height and materials that matter, not the type of doors you put in it. The exceptions are listed buildings, conservation areas, and properties with an Article 4 direction removing permitted development rights, where full planning permission is almost always required regardless of size. You can check the current rules yourself on the Planning Portal’s extension guidance — though we’d always recommend a proper site-specific check before assuming anything falls neatly inside the limits.
Rather than talk in the abstract, it’s worth looking at what this actually looks like once it’s built.
Our open-plan extension to a detached home in Newbury is a good example: large bi-fold doors opening the kitchen and living space straight onto the garden, designed to keep the whole rear elevation feeling bright and connected rather than boxed in.
We took a similar approach with a contemporary extension elsewhere in Newbury, where full-width glazing and bi-fold doors turned a dated rear elevation into an open-plan space that flows straight into the landscaped garden beyond.
And in Old Town, Swindon, a full-width rear extension with expansive glazing and a raised deck gave a dated family home a completely new relationship with its garden — proof that this approach works just as well on an older property as a newer one.
If you’re picturing your own kitchen extension with bi-fold doors, a few design decisions tend to make the biggest difference:
Not every architect designs extensions with this kind of light and flow in mind by default — some will simply add the square metres you ask for and leave the rest to the builder. The difference shows up in the details: where the roof lights sit relative to the doors, how the structural steels are hidden so nothing interrupts the glass line, how the extension reads from the garden as well as from inside.
When you’re looking for extension architects in Newbury, Berkshire, or anywhere across Oxfordshire and Wiltshire, it’s worth asking to see finished bi-fold door projects specifically, not just extensions in general — and asking how they’ve handled planning permission on similar schemes nearby, since local planning officers often have particular preferences about materials, roof lines and how an extension sits against a street scene.
This is exactly the approach we take at Kennet Design: full measured surveys, technical drawings that satisfy building control, and — where needed — early conversations with planning to make sure a beautiful design doesn’t stall at the application stage.
Thinking about an open-plan extension of your own? Get in touch with Kennet Design for a discovery call — we’ll help you work out what’s possible on your plot, and how much light you could actually let in.
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