In praise of the flexible frontier.
Believe it or not, there’s a lot of confusion about bi-folds. And it starts with the name: how should you spell it? Is it bifold, bi-fold, bi fold, or bifolding? People spell it all ways; we can get over that. But the big question is whether the bi-fold door is really a door at all.
The concertina magic of the bi-fold at first experience does have the appearance of a doorway although one of variable size. Does that make it more like a curtain (though not a curtain wall) perhaps? This flexibility is highly prized, and it trumps the sliding door by doubling the potential opening area. But what can it do beyond making it possible to change your furniture more easily or park the car in the kitchen (should you wish to).
It’s a trope of the rock star lifestyle to drive cars into swimming pools, but will bi-fold doors turn the kitchen into a garage?
For those whose homes look out to a paved terrace, the wide open bi-fold affords a more fluid interpretation of living space. That’s as true of the bi-fold closed as the bi-fold open. The wide expanse of glass, often floor to ceiling height, ensures an uninterrupted view even on cold or wet days when you’d rather keep the outside in its place.
Perhaps the way to think of bi-folds best is as the natural development of another triumph of modernism, the picture window. Unlike that permanent fixture, the bi-fold’s purpose is to sweep aside the limitations of windows altogether, resolving the transition from interior to exterior. But seen like that they do owe something more to window design than to doors.
If it’s both door and window, is it a windoor? It’s not a new idea to make something surprising of your access to the garden. Even in the eighteenth century, the most spectacular transitions were created. In one notable example at Heveningham in Suffolk, quite unexpectedly, a very normal looking sliding sash window in the ground floor hall concealed a door where the wall beneath was hinged to afford access to the terrace once the window was raised. The wall section had been replaced by a timber construction—operating like a stable door—faked to look like the rest of the wall.
Bi-folds, by contrast, make no secret of their possibilities. Transparency is all and it is a big part of the attraction. But despite their obvious advantages over conventional windows and doors, there is much that people still want to know, as a selection of recent online queries shows. Here we aim to answer a few of the most popular.
How much are bifold doors?
The eternal question has no easy answer. Pretty obviously, there are several design factors that influence cost and the choices you make will determine how costly they are. Size, number of folds, frame materials (normally PVCu or aluminium), and glazing type all greatly affect the cost.
Similarly, if you’re just replacing an existing door, it will be a lot cheaper than if you start knocking the place about to widen the opening.
Do I need planning permission for bifold doors?
Planning permission is rarely required for door replacement, but if you intend to remove a wall your reconstruction might need planning permission. Building regulations will need to be met by any construction and an engineer’s report is likely if you’re widening an existing gap.
If you are lucky enough to live in a listed property you will certainly need to seek listed building consent to change your doors.
Do I need a FENSA certificate for bifold doors?
Most bifold doors need a FENSA certificate to meet building regulation requirements as they have more than 50% glazing. If you’re already applying to building control to approve a new opening or enlargement of an existing opening, the door will be included in that application.
Are bifold doors energy efficient?
The short answer is yes, so long as they are closed. There are many options for door design and materials which can improve the thermal efficiency of bi-fold doors even where there are large areas of glazing. The quality of the frame design and the choice of glazing will influence the overall thermal efficiency and in most cases an estimate of the u-value will be available to help you decide.
Which materials are best for bi-fold doors?
Bifold Doors can be produced in PVCu, aluminum and timber and each has its advantages and disadvantages.
Structural stability – We recommend aluminium bi-fold doors as the strongest and most durable material, especially for larger openings. PVCu bi-folds are less costly, but they can be prone to heat expansion which makes their operation less smooth.
Maintenance and longevity – Again, aluminium offers some advantages over PVCu which needs more maintenance and timber which is high maintenance and has the shortest life.
Recyclability – Aluminum and hardwood are fully recyclable, PVCu slightly less so, although many PVCu frames are manufactured using majority reclaimed plastic.
Colour options and cost – Adding colour to PVCu is possible but normally entails additional cost. Hardwood frames can be painted in any colour although they generally need frequent repainting to stay looking fresh. Aluminium bi-fold doors normally come powder coated and a wide range of colours is available. Aluminium can also be produced in a flat, matt white to match any unfinished PVCu frames in the same room.
Browse our bi-fold door range
