Bifold doors, also known as folding doors, are those where panels concertina together when they open.
Bi-folding units can have doors that open inwards or outwards, and they can include a standard door at one end to use without folding the panels.
Bifold doors allow homeowners to flood interior spaces with natural light, making rooms feel much bigger, offering panoramic views and a smooth transition from inside to outside areas.
Bifold door systems can be a significant investment. With so many manufacturers and options to choose from, finding the right bifold door system for your home or commercial property can be a daunting task.
Making the right choice can result in a beautiful and practical addition to your home or office. Bi-fold doors can be fitted as part of a self-build scheme, a renovation project, or installation experts like Select Windows Systems.
To help you reach the right decision, we have put together a small guide on bifold windows basics. We hope you find it useful for choosing the right bi-fold door system for you.
There are three basic materials used in the construction of bifold doors – timber, uPVC and Aluminium – and all have their unique qualities.
Wood is the classic option for traditional buildings and period properties. We prefer hardwood for timber bi-folds as they are longer-lasting, need less maintenance and are less prone to warping than cheaper softwoods.
Although timber is naturally the most thermally efficient, it is prone to a contraction in colder weather, and this may cause draughts.
Timber bifold doors will need regular painting or varnishing to maintain their appearance.
Bifold doors manufactured from uPVC are similar in strength to timber, and they may also warp in extreme weather and may expand and contract as the temperature shifts.
While uPVC is a low maintenance material, it can suffer slight colouration from the sun and is scratched relatively easily. Generally, uPVC is very low maintenance and needs cleaning once a year with warm soapy water.
Aluminium is the most robust material and less liable to flex or warp, accommodating larger panes of glass.
Aluminium is also unlikely to expand or contract with temperatures changes. Although it is not as good an insulator, heat loss can be reduced by including 'thermal breaks' in the cavities.
Aluminium bifold use thinner frames and powder coating can give a durable finish in almost any colour and finished can be matched to most traditional homes
Bifold doors are not cheap, and it can be tempting to cut corners to bring down the overall price of installation.
But the design, manufacture and installation of bifold doors can have a massive impact on performance and durability. After all, bifold doors will end up replacing a large wall area of your property with fitted panes of glass. An inferior quality product could result in cold draughts, poor operational performance and lower security.
Modern manufacturers must meet basic quality standards on security, insulation, glazing and performance, but many will exceed the basics and provide a better lasting product for customers.
Here are a few quality issues to look out for:
Manufacturers may use remoulded scrap aluminium, which is cheaper but can come with surface imperfections that affect powder coating performance resulting in bubbles in the paint. Quality aluminium is made from prime billets sourced from high-end suppliers and comes with a completely smooth surface.
-The powder coating needs to be hard-wearing and should come with a 20-year guarantee.
-Manufacturers may offer low or standard quality industry weather standards, sufficient for average weather conditions but more likely to leak or produce draughts in poor weather. Weather-rated thresholds, also called rebated thresholds, ensure your doors are fully watertight.
-Look for window companies that offer higher than basic standards for air permeability, wind resistance and thermal ratings. Thermal efficiency, measured in U values, will help reduce fuel bills long term. The lower the value, the better, with the government standard for replacement doors or windows no higher than 1.8W.
Accessories can have a significant impact on the final finish and performance of the bifold doors systems. Items such as the running mechanism, the hinges and the locking components should meet high enough standards to add to the overall look and performance.
Handles should only be stylish, and they should also be ergonomic, robust and easy to use. The locking mechanisms should conform to PAS 24 standards, although many companies offer high security locking systems with their products.
Many manufacturers boast of good 'sightlines' for their products, but there is no standard measure for a sightline, and they are often measured differently.
Slim sightlines are more desirable, and aluminium offers the best compared to uPVC and timber. But take note that thicker sightlines can mean better security and greater durability. The bifold door profile should be as slim as possible while maintaining strength, durability and protection.
As with all window and door products, the price depends on a range of factors. These can include size, the number of doors, and the quality of material used and the standard of accessories.
Aluminium bifold doors are the most expensive to buy, but you need to set the outlay against the longer lifespan and low-cost maintenance.
The cost of timber bifold depends on the quality of wood. Solid and composite timbers are more expensive and, although they can last several decades, they do need to be adequately maintained.
Mass-produced uPVC bi-folds are the cheapest option, but the thick frames are not to everyone's taste, and they can discolour with age.