A buyer's guide to French doors

French doors open onto patio

If you ask a dozen homeowners what a French door is, you’ll probably get a dozen different answers. Some imagine a pair of glass doors leading to the garden. Others think of doors between the lounge and dining room. A few even describe sliding patio doors. It’s easy to see why people get confused, since the term has changed a lot over time.

Here’s the simple definition we use in our surveys: A French door is a pair of hinged doors, each attached to opposite sides of one frame and meeting in the middle, where most of the solid panels are replaced with glass. The key features are the pair of doors, the hinges, and the glass.

We install a lot of French doors across Cheshire, and they’re still one of the products our customers are happiest with. That’s partly because people know what to expect. No one buys a French door thinking it will be a six-metre glass wall. They choose it because it fits the house, lets in lots of daylight, opens onto the garden on warm evenings, and costs much less than other options.

However, French doors aren’t the best choice for every space, and we prefer to let you know that before you make a decision. There are size limits that can surprise people; you’ll need to decide which way the doors should open, and the type of threshold you pick can really matter if the doors are exposed to the weather.

In this guide, we’ll explain the history of French doors and why the design has endured. We’ll also look at how they’re different from patio and bifold doors, which sizes and proportions work best, how uPVC, aluminium, and timber compare, what security and threshold details to consider, and what you can expect to pay.

Where French doors came from and why

The history of French doors is more interesting than most products, and it helps explain their design. The concept began not in France but in Renaissance Italy, where advances in glassmaking allowed architects to build tall rectangular windows that reached low enough to double as doorways onto a balcony. Until then, glass was so rare in domestic buildings that most windows were covered with oilcloth or oiled paper.

French architects encountered the idea during the Italian Wars and brought it home, refining it with multiple small panes divided by glazing bars. By the mid-seventeenth century, under Louis XIV, the porte-fenêtre, literally the door-window, had become a signature of French classical architecture, running floor to ceiling in châteaux and grand town houses, and opening onto formal gardens and terraces.

The reasoning was entirely practical. Before electric light, daylight was the scarce resource, and a full-height glazed opening delivered far more of it than a window and a solid door ever could. The elegance was a happy consequence of solving a lighting problem.

The design crossed the Channel in the eighteenth century, and English architects took to it immediately, which is why so many Georgian and Victorian properties in Cheshire have them. Our climate gave the idea a second use, since a pair of doors that open wide provides summer ventilation that a single door cannot.

What strikes us, having fitted these for years, is how little the fundamental design has needed to change. The materials have transformed completely. The proportions of a good French door pair are essentially those the French settled on four hundred years ago.

How French doors differ from patio doors

This is the comparison we talk about most, and the main difference is how the doors work, not just how they look.

French doors are hinged. They swing, either outwards or inwards, from the sides of the frame. Sliding patio doors run horizontally on a track, with one panel passing behind another. Bifold doors are a run of hinged panels that concertina back and stack against a jamb.

This difference affects everything else. French doors open fully, so you get the entire width of the doorway as clear space. Sliding doors, on the other hand, only give you about half to two-thirds of the opening, since the panels slide behind each other.

The main trade-off is width. French doors work well up to about 1.8 metres wide, but get heavy and awkward if you go wider. Sliding and bifold doors are better for openings of three, four, or even six metres.

There’s something people often overlook until it’s too late: hinged doors need space to swing. If they open outwards, they’ll move across your patio and any furniture there. If they open inwards, they take up floor space inside. Sliding doors don’t have this issue. On a small terrace or in a tight dining room, this practical detail often makes the decision for you.

Here’s our honest advice: If your opening is under 1.8 metres, and you have a period or traditional property with enough space for the doors to swing, French doors are usually the better and more affordable choice. For openings over 2.4 metres, or if you want a true open-plan feel to the garden, bifold or sliding doors are better. For anything in between, it’s best to decide on site rather than in a showroom.

Sizes, sidelights and getting proportions right

In the UK, standard French door widths are 1.2, 1.5, and 1.8 metres, with 1.5 metres being the most popular. A 1.5-metre pair gives you about 1.4 metres of clear space once you include the frame, which is plenty for everyday use and moving furniture.

French doors at these widths have a design advantage that people often miss. With just two doors, there’s only one place where the glass is interrupted. If you compare a 1.8-metre French pair to a three-panel bifold of the same size, the French doors offer more visible glass because the bifold has two thick meeting points. For smaller openings, this can make the difference.

If your opening is too wide for a standard pair of doors, the usual solution is to add sidelights—fixed glass panels on either side of the doors. This way, you can fill a 2.5- or even 3-metre space while keeping the doors themselves a practical size. It’s a good option and one we often recommend, but remember: you get more glass overall, but the walk-through space stays the same.

When it comes to proportions, here’s advice we often share: If your home has Georgian or Victorian style, adding astragal or Georgian bars to the glass will look right. Leaving them out can make the installation look a bit off. For 1930s homes or modern builds, plain glass usually looks best.