R-Value for Insulation: Explanation, Best Ratings & Chart (2024)

Dreading another winter of astronomical heating bills? Proper home insulation could be your key to a warmer and cheaper winter, saving you between £630 and £730 annually. And for the biggest savings, deciding on the right R-value insulation for your home is crucial. 

Understanding the insulation value can significantly reduce your reliance on heating and cooling, saving you money year-round, all while improving your comfort of living.

In this article, you'll get the insulation R-value explained. We'll also break down the highest R-value insulation materials and answer the all-important question: "What is a good R-value for insulation in the UK?"

While our guide equips you with valuable knowledge, answering the question “What is R-value insulation?” on your own can take hours of strenuous research. This is why it’s best to ask a professional. 

GreenMatch offers a convenient solution—simply fill in our 30-second form, and we’ll connect you with up to 3 vetted professionals near you. Our service is free and non-binding. Click below to begin!

The R-value measures thermal resistance used in the building and construction to rate the effectiveness of insulation materials. Simply put, it tells you how good an insulation material is at resisting the heat flow. 

The higher the R-value, the better the insulation quality is. 

The R-value of insulation is calculated by dividing the thickness of the material (in meters) by its thermal conductivity (lambda value, λ), and it is expressed in units of square meter Kelvin per watt (m²K/W).

For example, if you have a 15 cm (0.15m) thick layer of glass wool with lambda of 0.035 W/mK, its R-value is calculated the following way:

R= 0.15/0.035 ≈ 4.3 m²K/W

While the R-value is a universal concept, it's important to note that the specific ratings you'll encounter in the UK might be presented differently. Instead of R-values, UK insulation building regulations often focus on U-values for insulation. 

But what is U-value insulation? Unlike R-rating insulation, it measures the rate of heat loss through a specific building element, like a wall or roof. Lower U values indicate better insulation performance and are expressed in W/m²K (Watts per square meter per Kelvin). 

For instance, the external wall U-value requirement in new buildings in the UK is typically around 0.18 W/m²K, equivalent to an R-value of 5.56 m²K/W. The U-value for existing walls is 0.30 W/m²K with an R-value insulation equivalent of 3.33 m²K/W.

Beyond just keeping you warm, the best R-value insulation solution for your home offers you a multitude of advantages. Let's explore some of the key benefits:

Also, important to note that insulated homes require less heating energy and lower energy consumption. This translates to fewer greenhouse gas emissions your household produces. 

Selecting biodegradable, recycled, or renewable insulation options such as cellulose, fibre, and wood wool could reduce your carbon footprint even further. 

The R-value varies among eco-friendly insulation materials. Therefore, it's important to consider both environmental impact and insulation performance when choosing a material. Let's take a closer look at the thermal resistance of the most common insulation materials.

Not all insulation materials are created equal; some of them offer significantly better thermal resistance than others. Let's delve into the key factors that affect the R-value of materials used in insulation:

Understanding these factors and material options helps UK homeowners make informed decisions about insulation, ensuring energy efficiency, comfort, and compliance with local building regulations.

Let's explore the R-values of common insulation materials to help you choose the right one for your home. 

It's highly recommended to choose the materials together with an experienced insulation expert. Yet, with such a high demand for insulation, booking a meeting with qualified professionals can be a real challenge. Thankfully, GreenMatch can simplify the process of searches for you. 

All you have to do is complete our 30-second form, and we’ll do the rest. You can then get up to 3 free and non-binding quotes and connect with our professional insulation installers network. This ensures that you can compare quotes from accredited suppliers. Click the button below to begin.

Understanding the R-value is crucial, but with so many insulation options available, it can be tricky to know where to start. 

In 2022, the UK government made significant updates to building regulations. They were aimed at improving energy efficiency and reducing carbon emissions in buildings. Among all, the updated Part L (Conservation of Fuel and Power) specifies minimum U-values for new constructions and renovations. 

In the chart below, we provide the U-values along with their R-value insulation equivalents:

As a homeowner, you should be aware of these requirements and consider the long-term benefits of proper insulation. However, with the new regulations coming in October 2024, it's best to consult a local insulation expert regarding any updated requirements. 

Above, we've provided general R-value requirements for the most optimal results. Yet, what is a good R-value for insulation in the UK? A good R-value for insulation is generally considered to be around 4.15 m²K/W. For optimal performance, aim for R-values above 4.54 m²K/W, especially for roof insulation.

The recommended insulation values for different building parts depend on the specific application and local climate conditions. Here are some general guidelines:

The choice of insulation material and thickness depends on the building's specific requirements, local climate conditions, and building regulations.

Selecting the right R-value for insulation is essential for achieving energy efficiency, comfort, and compliance with building regulations. 

In the UK, aiming for R-values around 3.30 m²K/W for walls and above 4.54 m²K/W for roofs is advisable. Always consider the specific requirements of your building and consult local building codes to ensure optimal insulation performance.

By understanding and choosing the appropriate R-values, you can significantly improve your home's thermal performance, reduce energy consumption, and slash your energy bills.

And for long-term savings, you must choose R-value insulation options that fit your home. An experienced professional can help you with that. However, finding a trustworthy expert in your area can drag on for days, if not weeks. A busy homeowner like you doesn't have so much time to spare!

Thankfully, GreenMatch can do the legwork for you. Fill out our 30-second form to get up to 3 quotes from our extensive network of vetted insulation professionals. No hidden fees or obligations to accept any offers. Simply click the button below to receive free quotes to compare.