Insulation R-value

Summer is the sensible time to be reviewing or renewing your winter insulation on your building. Insulation has become a confusing product to purchase with so many different products to choose from. Every product claims to do the job of insulation better than the other. So how do you choose? What is R-value? The fact is the higher the insulation R-value the better the performance of the insulation.

Choosing has been made easier because of the R-Value of a product. What is R-Value it not the Rand value but is a measure of the thermal resistance of a product or material. This valuable number tells you how fast a product will lose heat and this is important in insulation.

What is Insulation R-value?

What is Insulation R-Value this is not difficult but be sure to get the correct R-value. The higher the R-Value the better the product it at insulating and retaining heat. Proportional to the thickness of the product and inversely proportional to the thermal conductivity of the material, or K-Value, the R-Value defines the overall effectiveness of the product. Heat loss vs. Product Thickness is very much the important piece of information needed when choosing insulation. The R-Value is that information.

The R-Value and the K-Value are not just made up. After manufacture, all insulation products are sent for testing to determine the K-Value which in turn provides the R-Value. An R-value is a sign of quality. The R-Value also allows a person to see the difference in the performance of the many products on the market with some being more preferential than others due to the end-user.

What types of insulation products are there?

While there are many brands and what looks like an array of products to choose from there are only four types of the insulation product. Most roof insulation products are roll form insulation. The roll form insulation has the most consistent R-value as it has a consistent thickness.

Foam in Place

For the tricky places to get to, or for small jobs foam in place is an excellent choice of insulation material. The material is blown into space it needs to fill and left to expand and harden. This material is perfect for gaps around doors or windows.

Rigid Foam

Generally, an expensive choice owing to the high R-Value Rigid foam is a popular insulation material. Made from foam or polystyrene sheets the material can be cut to size and placed in the gaps and spaces that need to be filled.

Rolls and Batts

This is an extremely flexible insulation material and sometimes called an insulation blanket. Rolls and Batts come in sheets of material that are made from either fibreglass, polyester or other ceramic fibres. Easy to apply, Rolls and Batts are often excellent value for money with a long life span.


Made from cellulose loose-fill fibres or pellets is an insulation material that is blown into space. Often used for large spaces loose fill needs to be professional applied or installed for optimal results.

Using the Insulation R-Value to Select The Right Insulation

Be careful when using the Insulation R-Value to choose your Roof insulation material. There are some manufacturers who know how to cheat. Thankfully, most quality Roof insulation product providers have their test results on hand so always ask. If you are undertaking a large product or if you are a contractor asking to see the test results can be very worthwhile.

The R-Value does not necessarily guarantee the level of insulation a particular material will provide in your building. It is best to use the R-value as a guide because every building differs and has its own unique attributes that can alter the effectiveness of a product. If you are replacing rolls of insulation in your loft the R-Value won’t make a great deal of difference as like is being replaced with like.

However, if you are undertaking a large project and insulation review, or the insulation is for a new building the R-Value becomes important. Making the R-Value part of the project from the start makes sense rather than hoping to get good insulation after the fact.

What Is The Best Roof Insulation to Use

Remember every building is different and each insulation product is suited to particular needs. Having a variety of insulation products that may give you a lower average R-value could well provide better overall insulation. Make sure you fully understand what is R-value before making a decision.

Roof insulation products like the 145mm ISOTHERM or the 135mm AEROLITE have great R-VALUE specifications. Always make sure to install SANS compliant roof insulation.

There a few tips to ensure you purchase the right insulation for your property

  1. Get advice from a professional
  2. The thicker the material the higher the R-value
  3. If there is no R-value be cautious
  4. Check for SABS approval
  5. Ask about the long term effectiveness of the product

The R-Value really can help you when insulating your property but having the right product for the job is always important.