Pitched Roof Insulation – How to Achieve a U-Value of 0.15

4 minute read

U-Values are becoming more stringent, but TLX Silver and TLX Gold achieve excellent levels of insulation whilst having the least disruption to the roof. TLX multifoil insulation helps to improve the U-Value of a roof whilst preventing condensation risk. For pitched roof insulation you can achieve a U-Value of 0.15 alongside using additional insulation.

What is the U-Value of TLX Silver and TLX Gold?

This question is a common one, but a very tricky one to answer. The reason for this is that you cannot give a U-Value to a single insulating product, it simply doesn’t have one. A U-Value is a measurement of the rate of heat loss or gain through a particular material or assembly, such as walls, roofs, windows, or doors. It quantifies the thermal conductivity of a component or structure, indicating how well it can resist the flow of heat. A lower U-Value indicates better insulation properties since less heat is being lost.

So how do we achieve a U-Value of 0.15 W/m²K? Some products are more effective insulators than others and this is determined by the R-Value of a product. An R-Value is a measure of how effectively a material prevents heat transfer from a warm space to a cold space. The higher the R-Value, the greater the insulation capacity. TLX Silver and TLX Gold work in different ways to help achieve low U-Values.

How to Achieve a U-Value of 0.15 for Pitched Roof Insulation with TLX Silver

TLX Silver multifoil insulation is a 2-in-1 insulating vapour barrier. It has shiny outer layers that reflect heat back across this surface and project it back into the room, keeping it warm. These reflective layers also work to prevent heat from entering the building in summer too.

To install TLX Silver multifoil insulation you will need to:

This build up achieves a U-Value of 0.15 W/m²K.

*If you prefer, use mineral wool in place of PIR board. For this, you will need 200mm of mineral wool between 240mm rafters at 400mm centres to meet 0.15.

How to Achieve 0.15 U-Value in a Pitched Roof with TLX Gold

TLX Gold multifoil insulation is a 2-in-1 insulating breathable membrane. It has a shiny breathable under surface which reflects heat.

The draped method:

If you have a listed building or if you are unable to raise your roof, using TLX Gold draped requires no change in roof height. It’s the perfect solution for this type of project. In order to install TLX Gold using the draped method, you will need to:

This build up achieves a U-Value of 0.15 W/m²K. You can read the case study here.

*Instead, you could use mineral wool. In order to this, install 220mm between 285mm rafters at 400mm centres to meet a U value of 0.15 W/m²K.

The taut and counter-battened method:

This build up achieves a U-Value of  0.15 W/m²K.

*Using 225mm of mineral wool between 265mm rafters at 400mm centres will also meet a U-Value of 0.15.

Do You Require a Bespoke Solution?

Whether you need pitched roof insulation for an extension, renovation, or barn conversion, TLX insulation has the answers. We have over 15 years of research and development into multifoils and have tailored our products to provide excellent levels of insulation, whilst minimising the build up and managing condensation risk.

We would love to hear from you. Our helpful team of product experts are on hand to help with bespoke solutions and U-Value calculations For technical queries, simply call +44 (0)1204 674 730. Also, our LABC-approved solutions guide has a wide range of pre-calculated solutions. You can download your free copy from the footer below.