Which Material is Best for Bi-Fold Doors?

Bi-Fold doors may seem like a daunting concept, considering the materials that are available, the prices, the installation and even the affect your location can have on their longevity.

However, Sash Windows have taken the time to analyse how aluminium, uPVC and timber compare on qualities such as maintenance, thermal efficiency, strength and cost.

So, you’ve made the decision to purchase bi-fold doors, good work, but what now? There are many things to consider aside from placement and size. Different materials serve different purposes when it comes to performance, life, and aesthetics.

This begs the question, how do you decide what type of bi-fold doors are right for you?


Strength is one of the most important factors to consider as the frames need to support huge panes of glass and be durable enough to withstand constant use and bad weather.As many people living on the southern coast will know, we are accustomed to gale force winds from time to time. That is a major reason why strength is an important factor to consider when installing your bi-fold doors.

Your standard options (unless you’re looking for bespoke designs/materials) are:


Aluminium headlines the strength rating with uPVC and timber following behind. Aluminium can therefore support more glass on thinner frames. This in turn, allows you to keep the framework to a minimum, which means more light and better views!

Another positive of using aluminium is that the metal can be specific for corner posts and bay windows, which is not possible with uPVC or timber. Unlike timber, aluminium is not prone to flexing or twisting under pressure or weather impact. The metal is also well suited to varying temperatures as they don’t expand or contract with heat variation.

This makes them a great choice for coastal locations, or places where they are exposed to direct sunlight on a frequent basis.


  • Ideal for coastal homes
  • Strongest material on the market
  • Lightweight and easy to use
  • Easy to adapt to the trickiest structures



The timber you usually find in bi-fold doors is engineered timber. This form is far stronger than solid timber as it is made from pieces of wood glued together with polyurethane. These combined layers provide the strength to the foundation. Timber also looks fantastic, depending on your style and preference, timber can really bring out the history of your house. They also look very sleek and natural, which adds a touch of retro-class to your property.

If it’s aesthetics you’re looking for, timber is arguably your best option.

Despite its aesthetic pleasures, timber is prone to warping if it absorbs too much moisture or is overexposed to direct sunlight. Once the timber is warped, the gaskets cannot be sealed properly, meaning the doors will not fully close, leading to draughts and weak-points.


  • Aesthetically beautiful
  • Strong, though can be heavy to maneuver
  • Engineered wood is much stronger than solid timber



Bi-fold doors made from uPVC offer roughly the same strength as timber. They are also prone to warp much like timber, again, if overexposed to strong weather and heat variation. Meaning that they can become damaged and therefore become difficult to open or close.


  • Easily fitted and maintained
  • Vulnerable to warping and temperature changes


Thermal Efficiency

sky-383823_1920It is mandatory that all bi-fold doors must have a U-value of at least 1.8W/m2 (this is for the glass and framework combined). In short, the lower the value, the better the material acts as a heat insulator.As glazing forefronts the core majority of the bi-fold door, it is the glass that has the biggest impact on thermal efficiency. Thermal efficiency is measured in what we known as a U-value. This represents the rate at which heat passes through a material, which in turn highlights it’s insulation efficiency.


Metal is naturally a good conductor, so aluminium appears to have already  lost the thermal efficiency battle. However, most aluminium bi-fold doors include a thermal break. The break is made of a less conductive material and sits between the interior and exterior faces of the frame to manage heat loss.

Aluminium doors also have the huge advantage of being environmentally friendly. Due to its high recycle rates, many companies construct their doors from recycled metal.


  • Thermal breaks can be applied to frames to lessen the U-value
  • Recycled aluminium benefits the environment


Timber is less conductive than metal. The average timber bi-fold door has a U-value of 1.4W/m2, which is already lower than aluminium doors without the need of a thermal break. Efficiency can be improved using similar methods to those used for aluminium doors, but as timber doors are prone to contracting/warping in cold weather, their thermal efficiency can be affected.

If you do opt for timber, be sure to look for woof that comes from a Forestry Stewardship Council certified source.


  • The U-value for timber is 1.4W/m2 (relatively low)



With a average U-value of 1.7W/m2, it ranks just slightly lower than aluminium. Similar to timber, efficiency can be affected by harsh weather or long exposure to direct sunlight.

uPVC unfortunately is also the least environmentally friendly. If you are swaying toward uPVC, it might be an idea to ask the supplier if the material has come from a recycled source.


  • None (unless your source recycled uPVC material)



If you’re spending money on bi-fold doors, you want to ensure they’re easy to maintain. So, it makes sense to choose a material that will be able to handle the region your property is located in.

Aluminium is actually very low maintenance. The doors are coated and don’t require repainting, they will no corrode, discolour, rot, warp and they are resistant to fading in the sunlight. All they need is yearly cleaning with soap and water!


  • Extremely low maintenance
  • No rust, rot, warping, sun-damage and weather resistant


Timber bi-fold doors will require the most maintenance. Wood requires sealant in order to prevent moisture damage and warping. Varnish and creosote are all that’s needed to keep them strong and moisture-free.


  • Considering their aesthetic value, yearly painting is a small price to pay to keep them strong



While uPVC is very low maintenance, it is not invulnerable. Sunlight is its biggest enemy, it’s also more susceptible to marks and scratches. Similar to aluminium, clean them once a year with soap and water to keep them looking good.


  • Low maintenance – soap and water once a year
  • No need for painting!


And finally, PRICE!

cost-1174937_1920Whilst cost may be a major factor, it is more important to select doors that are appropriate for your property’s area. Put it this way, if you decide to go cheaper on a material that isn’t suited for your coastal area, you’ll end up spending more money repairing and maintaining it than if you spent a little extra on a material that requires lower maintenance.

It’s more sensible to spend money on a product that will last a lifetime than one that will eventually deteriorate for a lower initial cost.


These are the most expensive. However, they are also the most durable, it is very unlikely that you will have to purchase new doors as these are built to last well over 30 years. Aluminum doors are more durable than both timber and uPVC.

Cost: roughly £3,000 for a four bi-fold door set (excluding glass and installation)



Here, you are paying for the look. Yes, they are more vulnerable to damage and yes they require the most maintenance. Though this is the price you must pay if you want to achieve that woodland/sleek look. The prices vary on the type of wood material you desire.



Engineered timber: roughly £2,000

Solid timber: roughly £3,000

Composite timber: roughly £5,000



Due to the fact they are mass produced, uPVC are the cheapest option by far. Most carry a 10-year guarantee, though take into account that the doors may be affected by direct sunlight and harsh weather.

Cost: roughly £1,500