Buying bi-folding doors help and advice

During the last decade there has been an increase in the numbers of double glazed bi-folding and sliding doors installed in new build homes, extensions and refurbishment projects in the UK. This trend is somewhat surprisingly given the unpredictability of the British weather, but despite this unknown variable, hundreds of thousands of UK home owners have decided that, regardless of the changing English Climate, they want the option of being able to completely open up their living space to the outdoor elements.

The noticable increase in the number of folding and sliding doors sales has generated real growth in the sectors of the double glazing industry who manufacture these products, with many different types of bi-folding designs and materials on offer, including aluminium, hardwood timber and PVCu double glazed doors. Within each of these material types the quality of double glazed doors varies an awful lot. Consequently, there are plenty of horror stories where property owners have fitted products primarily because they were the “least expensive”, only to find at some point in the future, that they are not fit for purpose. Unfortunately, for those discerning folk wanting long lasting, thermally efficient, well fitted double glazed bespoke bi-folding doors, these are not inexpensive products, and like most double glazing products, one does tend to get what one pays for on the whole.

For example, double glazed plastic doors are made of unplasticized polyvinyl chloride (UPVC), so are not as robust and secure as metal doors, but they are of course cheaper! Also being plastic, UPVC (also known as PVCu) folding and sliding doors do tend to flex, and expand and contract a fair bit, which is not ideal for a bi-folding door system that needs to be rigid to operate efficiently and not move out of alignment. Timber hardwood sliding doors look great, but unlike aluminium and UPVC double glazed doors are not maintenance free from a decorating point of view, plus do tend to be the most expensive option of all.

High quality bespoke powder coated aluminium bi-folding double glazed doors do cost a far bit, but are worth the investment as they deliver superb thermal efficiency, high security, low maintenance, plus have the advantage that they can be manufactured in any powder coated RAL colour inside and out, as well as in a real timber woodgrain effect finish. Aluminium, being metal can cover larger spans and heights than other bi-folding door materials, plus is a 100% recyclable material, so is “the green metal” and very environmentally friendly.

Bi-folding door on an Orangery
Double glazed bi-folding doors on an Orangery

Each different bi-folding door manufacturer’s products have their particular benefits and features, so it is worth doing your research and then choosing the best possible specification whether refurbishing your home, or building a new house, or adding an extension to your property. Take the Sapa Dualfold double glazed aluminium sliding door system. If you select to have all the doors in this system opening inwards with a standard threshold, they will have a weather rating of 150 Pascals. If however, like the majority of home owners you decide to have all the doors opening outwards, this Sapa aluminium double glazed sliding door system will have a decent weather rating of 600 Pascals (assuming a standard threshold is specified). If you choose the low threshold option, the weather rating is only 50 Pascals, so it is strongly advisable when fitting replacement bi-folding doors to exposed external elevations to go for the standard height threshold option.

Getting the right configuration for each opening is very important, be it an existing or new aperture. Every folding doors system, whether aluminium, PVCu or timber has maximum and minimum sizes that can be achieved. Remember that the more folds you go for mean more cost, more uprights, narrower overall opening, less glass, less light and less views! As aluminium can operate to greater heights and widths than weaker materials, it enables property owners to have less uprights, thereby permitting more double glazing and better solar gain. Folding and sliding doors hinged together operate in pairs, so a two, four or six section configuration all slides in one direction, so cannot have a “travel door” with a door handle. To open them a minimum of two sections have to move at same time in order for the doors to operate. A distinctive advantage of a three, five or seven section folding door that all slide in one direction,  is that these configurations enable the end section to act as a travel door with a proper door handle. It is possible to get four and six section doors with a travel door, where one door (in the case of four section) is side hinged at one end and three sections slide the other way, and in the case of six section configuration, have three sliding sections going one way and three sliding sections going the opposite way. Normally, such configurations have a “built in” option of having a set of French doors as well as single door and folding/sliding doors, so property owners get three different door operations in one, hence why getting the right configuration first time is vitally is important when buying replacement bi-folding doors


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