Typically made of wood, UPVC or aluminium, bi-fold doors consist of three or more patio doors that fold back on themselves and sit flat against one or both walls, often with a separate, ‘lead’ door. They look most impressive when they span a whole wall or walls - which means when the weather’s nice, you can fold them back to open up an indoors-outdoors room.
Ideally, the floor/ground levels on either side of bi-fold doors should be the same. This may involve some work in the garden, but it will improve the indoor-outdoor flow and increase the wow factor, especially if you use the same, or similar, flooring on both sides. Engineered or solid wood flooring inside and decking outside works well.
Bi-fold doors are often fitted in new extensions, but if you’re retrofitting them, you’ll probably have to replaster, redecorate and move things like radiators, sockets and switches to make space for the doors. Off-the-shelf bi-fold doors are available, but doors are often made to order.
Unless you have an existing window/door that’s the same as, or bigger than, the size of the opening required for the bi-fold doors, a new lintel will have to be fitted above the opening for support. Your first step (at the planning stage) should be to consult a structural engineer, or use a reputable window and door company, to supply and fit the doors. They should carry out a survey and do whatever’s necessary to make your home structurally sound.
Planning permission isn’t usually required for bi-fold doors, but there are exceptions so do check. If your home’s listed, you’ll need listed building consent from your local council to fit bi-fold doors, and if you live in a leasehold flat or house, you may need the freeholder’s permissionIf you get a builder to fit the bi-fold doors, it’s important to get the work checked and signed off by a building control inspector (either from your local council or a private firm) to ensure it complies with building regulations. The easiest option is to have the doors fitted by a window and door company that can self-certify that their work complies, such as companies belonging to FENSA (www.fensa.co.uk). If the manufacturer fits the doors, you should get a guarantee and their assistance if anything goes wrong with them, but if they only supply them and your builder fits them, you may be left with problems no one wants to take responsibility for.