U-Values: What Are They and How Do I Calculate Mine?

Whether you’re taking on a new building project or are looking to increase the energy efficiency of an existing building, you’ve undoubtedly heard of ‘U-values’. The mythical term is often referred to in planning permission documents and on various building materials. It is therefore important to have a clear understanding of U-values to ensure you buy the materials required to fulfil the requirements of Building Regulations.

Why Do They Matter?

There are strict requirements set out by the government regarding U-values. This is in order to ensure that both new and old properties have minimal impact on the environment by ensuring that any warmth generated by heating appliances does not escape through walls, doors, windows and roofs.

The lower the U-value, the greater the insulation. The U-value is measured in Watts per square meter, per degree Kelvin. This is presented as ‘W/m2K’ in planning permission documentation and on some building materials.

What is a U-value?

Entire building parts, such as a roof, are awarded a U-value. This is a measurement of how effective that particular part of the building is at preventing heat transmitting between the inside and outside of the property. The U-value is dictated by the various materials used, such as the roof tiles or insulation in the case of a roof.

When buying building materials, you will note that they often have their own U-value. This is determined in the same way as the U-value of a particular part of a building. However, the U-value of a one material does not determine the overall U-value of your property. This is as the overall U-value is determined by the combination of building materials used and their individual U-values.

What Level of Insulation Must I Achieve?

As of 2017, the required U-value for various building parts varied from 0.16 W/m2K to 0.26 W/m2K. They are, however, subject to change and you should check with your local authority before undertaking a project or buying any materials.

This is particularly important as the recommended U-value can vary per region, with England, Wales and Scotland each having their own requirements. The necessary U-value also varies based on the building type (i.e. domestic or non-domestic) and age (i.e. new build or existing building).

How Do I Calculate My U-value?

Calculating the U-value of your property is anything but easy. For this reason, you will benefit from utilising the skills of a specialist such as Kingspan. They will calculate the U-value of your property. Their detailed report will then outline whether your property complies with current Building Regulations and, if it doesn’t, what improvements can be made.

If you’re looking for the U-value of a specific building material, simply contact the manufacturer. Roofing Megastore make it even easier by displaying the U-values of many materials online. This includes our range of roof windows, polycarbonate sheets and insulation.

Have More Questions About Insulating Your Property?

If you have more questions about U-values or our range of insulation, please get in touch. With over 40 years of experience in roofing, we’ll help you pick the necessary materials to minimise your U-value. What’s more, with mega savings on 1,000’s of materials you’ll complete your project at a fraction of the price.


PLEASE NOTE: THIS GUIDE ON U-VALUES HAS BEEN WRITTEN FOR INFORMATION PURPOSES AND WE THEREFORE TAKE NO RESPONSIBILITY FOR ANY PURCHASING DECISIONS YOU MAKE OR INSTALLATION PROCESSES YOU FOLLOW AS A RESULT OF READING THIS ARTICLE. WHILST WE ACT AS A RETAILER, WE ARE NOT EXPERTS NOR QUALIFIED IN INSULATION OR ANY OTHER ROOFING MATERIAL. WE THEREFORE RECOMMEND THAT YOU REFER TO YOUR MANUFACTURER'S GUIDE AND, IF APPROPRIATE, CONSULT A QUALIFIED PROFESSIONAL.