October 5, 2022

Specific Uw Values for Slim Sliding Doors

Written by Rebecca Clayton

specific Uw values for slim sliding doors

Specific Uw values for slim sliding doors are calculated on a project-by-project basis, as there are many factors such as size and glass specification that affect this.  


With the updates to building regulations and the improved Uw value requirements for glazing, there is a misconception that this will mean that glazing specifications will need to change to composite systems. 


This is definitely not the case. If your design calls for slim framed aluminium sliding doors this is still very possible if specified correctly. 


Due to the bespoke nature of IQ’s glazing systems, many are stated as having a ‘Uw from...’ which isn’t always the most helpful, but it's all that can be given without knowing the specific glazing specification.  


This article shows some of our projects where bespoke sliding doors were specified and what Uw values that specific installation achieved to help give an idea of what is possible.

interior view of a rear slim framed patio door with an offset corner post with glass corner

How are Uw values calculated? 

A Uw value is the overall thermal performance of the glazing system as a whole. The unit of the thermal insulation value is given in W/m2K, which means “Watt per square metre and Kelvin”. 

This is calculated using the thermal performance of the glass (Ug), the framework (Uf) and the glazing spacer (PSIG), along with the sizes of the opening, opening configurations and framing design, to give you an overall Uw value. 

Building Regulations for Sliding Door Uw Values  

Approved Document L of the UK building regulations focuses on the consumption of fuel and power, outlining requirements that help to create sustainable, low carbon building designs.  

Bright modern kitchen living room offers riverside views through full height glass featured on Grand Designs

The new limiting standard for glazed windows and doors is Uw 1.6 W/m2K for new dwellings, Uw 1.4 W/m2K for extensions to existing dwellings and Uw 1.6 W/m2K on buildings other than dwellings.  

These figures are very possible to achieve and surpass with the minimal windows sliding door systems and structural glazing. We work on many projects where architects are creating a sustainable or low carbon build with these systems. 

IQ's slim sliding doors are manufactured with a polyamide thermal break and a low e coating as standard, enabling them to achieve high thermal performance values without having to compromise on a modern and minimal design.


Uw Values for Slim Sliding Doors  

Claywood House 

This sustainable new build dwelling has so many interesting elements for it. The five-bed family home was designed to be low carbon and wheelchair user friendly. This means that specifying thermally efficient glazing with a flush threshold for accessibility was vital.  

minimal windows Sliding Doors were specified with Uw values 1.38 – 1.55 W/m2K, double glazed. 

Claywood House thermally efficient dwelling with high performance glazing by IQ

Kew Road  

A rear extension in London with bespoke structural glazing and double-glazed minimal windows® Sliding Doors. The thermally broken aluminium sliding doors achieve a Uw value of 1.29 W/m2K. 

To surpass the thermal insulation requirements of the UK building regulations, the triple glazed version of minimal windows (minimal windows 4+) offers a Uw value from 0.8 W/m2K, making the system an ideal choice for projects looking to exceed the requirements. 

Cambridge University  

A glass extension was added to Jesus College at Cambridge University for a new café area. The project included triple glazing minimal windows 4+ Sliding Doors with Uw value 0.80 W/m2K. 

This help to maintain a comfortable temperature in the new internal space all year round. 

Future Proofing Your Home's Glazing

With the temperatures becoming more unpredictable each year, and UK building regulations becoming more stringent, it is more important than ever to be specifying building materials that help to future proof your home.

This includes specifying thermally efficient glazing and looking at factors such as low Uw values for slim sliding doors. On the other hand, specifying glazing with a solar control coating can help to prevent overheating in internal living spaces during the warmer months.

IQ are always looking to push the boundaries of modern architectural glazing, and there are ways to improve the Uw value of sliding doors such as specifying triple glazing. Our sliding door systems all use thermally broken profiles, which are made from 70% recycled aluminium, and are manufactured with a low e coating as standard. 

Typical height glass box extension

What Next? 

We are always happy to work with architects to specify the glazing they need to the performance requirements. If you can tell us the required Uw values, you need we can specify the glass systems and configurations that are suitable. 

To discuss specific Uw values for slim sliding doors, contact the IQ team today