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A Guide To R-Value

When purchasing insulation for your home, one term that you will come across is R-Value. But, what exactly does R-Value mean and how does it impact your choice of material?

What is R-Value?
R-Value is the measure of a product’s ability to resist the transfer of heat (thermal resistance). Insulation materials are designed to retain heat, helping to keep your home cooler in summer and warmer in winter. This reduces the need to rely on expensive artificial heating and cooling methods, saving you money in the long-term and reducing your impact on the environment.

How is it calculated?
Two factors affect thermal resistance – the thickness and the thermal conductivity (K-Value) of the material. The R-Value is calculated using the following formula:

R-Value (m² K/W) = Thickness (m) / Thermal conductivity (W/mK)

What should I look for when choosing an insulation material?
Simply put, you want to choose a material with a high R-Value. The higher the R-Value, the more effective the insulation material will be at helping you to maintain a level of thermal comfort in your building.

According to the SANS10400 legislation in South Africa, new homes need to achieve a minimum R-Value. This figure is based on where your home is located and differs from area to area.

The minimum R-Value can be achieved by using a combination of different insulation materials throughout the roofing system, such as insulated ceiling boards and ceiling blankets. At Roof Handler, we stock a wide variety of these products like Isoboard, Lambdaboard and Earthwool. When combined, these materials can help you to achieve the desired R-Value.

Other factors to consider
You might also want to consider some of these factors when choosing an insulation material.

• Fire rating
• Lifespan
• Ease of installation

To find out more about the insulation materials available, speak to one of our roofing experts by calling 044 873 0627.