The Advantages of a 55mm Frame Slimline Bifold Door

Now Aluminium offer a 55mm frame as standard – one of the slimmest on the market. But what are the advantages of having a slim frame? Find out in our latest blog.

Energy Efficiency

It’s easy to assume that a physical divide that is mainly made up of a glass panel could never be a great insulator, however you would be wrong! Glass systems have developed hugely over the last 10 years and now our choice of glazing – Planitherm from Saint Gobain) – is AAA rated and loses almost no heat. Where the frames meet, we use weatherproof insulating seals. Overall, our NW1 aluminium bifold provides an incredibly low u value of 1.4. In comparison, a standard cavity wall provides a u value of 1.6 – 1.7 leaving the bifold the clear winner. As the glazing used in bifold door systems are far more efficient than the frame itself, a slimmer frame ensures more glass is used, hence greater energy efficiency.

This is why bifolds can be a perfect addition for the winter – whilst they come into their own when opening fully on warm summer days, they help keep energy bills lower in the colder months.


A slimmer frame means more glass. Therefore there is more natural light entering a property and provides a better view of the outside from the interior. With the doors closed for much of the winter months, a slimline door system maximises these benefits over a more bulky door frame. If you have a traffic door, you can still allow for ease of access and what’s more, the doors can be opened even if just to get the Christmas tree in! With a lower sun in the winter time, more daylight will be entering a property through the vertical glazing products as opposed to horizontal roof lights/lanterns. Bifolding doors with a slimmer frame will maximise the amount of sunlight entering your home providing a far brighter living environment – wherever you live in the UK.

To find out more, get in touch with one of the NOW Aluminium team today!