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U Values Explained | Eco-Roof™ & Insulation I Ploughcroft

U Values Explained | Eco-Roof™ & Insulation I Ploughcroft

The U-Value Explained (and Why Your Roofer Should Understand This)

When it comes to home insulation, one of the most important yet confusing terms is the ‘U-Value’, the measure of how effective a given material is as an insulator, and it’s referred to a lot in the building and construction industry.

However, the alarming fact is the vast majority of roofers still don’t understand what U-Values actually mean. For those professing to be able to offer effective heat insulation, that’s just not good enough. However, we’re here to provide an overview of U-Values and explain their importance when it comes to home insulation.

Here are the basics. In simple terms, the lower the U-value, the better a material is as a heat insulator. The U-value allows you to measure how much heat will move through any given material per square metre per hour. Therefore, it illustrates how effective a material is as a heat insulator by indicating how quickly it will lose heat.

The U-value is measured in units of Watts-Per-Metre-Square-Kelvin (W/m2K). However, understanding the basis of how it is calculated is less important than understanding how to compare materials by their U-value in order to insulate your home with the most appropriate materials.

Below are some examples of common building materials and their typical U-values:

  • Cavity walls most often have a U-value of 1.6 W/m²
  • Solid brick walls normally have a U-value of 2.0 W/m²
  • Solid floors normally have a U-value of 2.1 W/m²

As you can see from the above, a cavity wall is the best heat insulator due to the fact it has the lowest U-value, whereas the solid floor is the worst as it has the highest U-value. The best insulating materials have a U-value of close to zero; the closer to zero the better. Under the Green Deal and other energy efficiency schemes, the retrofitting of insulation to existing buildings requires the following U-value targets:

  • Wall – 0.3 W/m2k
  • Roof – 0.18 W/m2k
  • Floor – 0.25 W/m2k

Ensuring the U-value of your home is as low as possible is important as this means your home is not rapidly losing heat and is often an indicator of high levels of insulation, making your home more energy-efficient. If your U-value is high, then this is often an indicator that you may need to add additional insulation to your home.

So how can you ensure your home has the best U-Value?

Internal Wall Insulation

This is appropriate for homes built with solid walls, which are most common in pre-1930 builds. Unfortunately, energy efficiency was not on the agenda at this time and therefore this type of home lacks insulation and can be very expensive to heat.

An un-insulated solid wall has a typical U-value of 2.20 W/m2k, however, through adding internal wall insulation this can be brought down to approximately 0.3 W/m2k. As a result, not only will internal wall insulation give you a warmer, more comfortable home, but it could also save you up to £500 per year on energy bills.

Cavity Wall Insulation

Cavity walls became common post-1930. However, until the late 1990s, most of these walls remained unfilled, meaning they too were un-insulated. An unfilled cavity wall can have a U-value of anywhere between 1.6 W/m2k and 0.6 W/m2k, depending on when it was built.

By installing cavity wall insulation in your home you can help to improve your U-value and in turn, improve the insulation of your home to about 0.3 W/m2k.

Roof Insulation

25% of your home’s heat is lost through the roof, and even more heat escapes if you have a room-in-the-roof or attic bedroom, therefore it is vital to ensure your roof has the correct U-value and is as energy efficient as possible. An uninsulated roof has a U-value of approximately 2.5 W/m2k, however, adding insulation can achieve a value of 0.18 W/m2k.

If your home was built pre-1967 and has an old attic room or loft conversion, a great way of achieving this level of insulation is through our specially designed Eco-Roof™. The Eco-Roof™ is a high-tech insulated roofing system designed to offer homeowners a highly efficient way to insulate old loft/attic conversions and literally stop your money going through the roof by keeping the energy in and, in turn, keeping your heating bills down.

Not only can the Eco-Roof™ dramatically decrease your roof’s U-value, but it can also save you up to £500 per year. To find out more, watch our video featuring RooferMan.

Hopefully, this blog post has helped you to better understand the ins and outs of the term ‘U-Value’ and how it relates to the level of insulation in your home. Speak to the average roofer and ask them what U Value they will offer you for insulating a roof based on its size we bet you 99% won’t have an answer. However, if this is the case we suggest you question why you are working with them. If you have any questions or would like to ask us how we can improve the U-value of your home, feel free to contact us at info@ploughcroftuk.co.uk.


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