Choosing the Best Doors for Your Home Extension Project

People prioritise location, especially in London, but don’t want to compromise on modern, healthier and more convenient way of living. We seek more space, light and open plan living to create better experience for all household members. We modify and adapt old London townhouses and rear extensions are great solutions. Usually unable to extend sideways, we expand property into the garden creating long but narrow, tunnel-like space. This is where light plays extremely important role. Property owners and architects choose glass roof systems together with a set of patio doors. And it is the door choice that usually creates the biggest dilemma – sliding patio or bi-fold doors? 

The biggest advantage of sliding patio doors is the higher glass to frame ratio. While bi-fold door can go up to 1200mm in width per panel, sliding patio doors can carry a weight of 300kg-500kg per panel. This creates a large sliding door with wide, unobstructed glass units.


As sliding doors panels slide onto one another, the door cannot be fully open. This is where bi- fold doors stand out and allow for the extension to be fully open to the garden or patio, bringing the outside in. Although our British weather does not guarantee many opportunities to fully enjoy this solution, the popularity of bi-fold doors proves that homeowners love the idea anyway.

Another great feature of bi-fold doors is the traffic door which enables for a quick access in and out of the property. Simply, you can use one door panel which will act like a common door without a need to slide and fold the whole door system. Sliding patio doors are also easy to operate but might be heavier than bifold.


Grabex Windows had spent many years researching the best profit and technologies before deciding on aluminium Reynaers product line. Sliding patio and bifold doors range varies from standard frame thickness door sets to ultra slim most demanding customers and high end projects.

Now all aluminium systems should be thermally broken and offer great energy efficiency performance. However, it is worth to remember that in terms of thermal performance sliding patio door will usually perform slightly better than bi-fold. Generally speaking, aluminium frame is the weak point where the glass carries the thermal benefit Therefore, the more glass and less frame the better the thermal insulation of a product.


In terms of cost both systems are really similar unless the doors get really big. As mentioned before sliding doors can take more glass weight per panel. Systems with supersized panels will cost more because bigger and heavier double glazed units are very expensive. This will also affect the installation fee as extra labour will be required in handling the heavy glass.

In summary, if you want to be able to fully open the doors to give the seamless transition from inside to outside, then bi-fold system is your solution. If you want to reduce the amount of frame and maximise glass sizes, making the most of the view, go for sliding doors.

If you are planning a project and need some help with choosing right windows or doors for your home, visit Grabex Windows at their stand B120 or see their website They are expert manufacturer in aluminium, timber and Modus windows, doors and glass systems.