R-Values for Common Types of Insulation.

What are R-values?

R-values are used to determine how good a material is at minimising heat loss. Every material has an R-value. For example, plywood has an R-value of R-1.25 per inch, whereas our closed-cell spray foam insulation has an R-value of approximately R-6.5 per inch. The higher the R-value, the better the material is at resisting the flow of heat. The better the material is at resisting the flow of heat, the less energy you use.

R-values help differentiate between a good insulator and a poor one.

metric r value definition
NSAI Agrement logo

Common Insulation Materials

Below you will find a list of common insulation materials and their respective R-values per inch. All information has been taken from a document published by The University of Washington. You can find it here.


R-value (per inch)

Fiberglass Batt


Fiberglass Blown (attic)


Fiberglass Blown (wall)


Rock Wool Batt


Rock Wool Blown


Cellulose Blown (attic)


Cellulose Blown (wall)




Autoclaved Aerated Concrete


Urea Terpolymer Foam


Rigid Fiberglass (> 4lb/ft3)


Expanded Polystyrene (beadboard)


Extruded Polystyrene


Polyurethane (foamed-in-place)


Polyisocyanurate (foil-faced)


As you can see, spray foam insulation is undoubtedly one of the best commercially available insulation choices for both domestic and commercial use. The foam expands to fit any cracks and crevices which guarantees an airtight seal and minimises heat loss. You can see this expansion here. In contrast, fiberglass and cellulose insulation do not provide an airtight seal. As you can see above, both fiberglass and cellulose insulation have a lower R-values than spray foam.

You can find a more comprehensive comparison of fiberglass, cellulose and spray foam insulation here. We also have a concise list of benefits regarding spray foam here.

If you would like a free quotation freephone 1800 911500 or email us at info@myfoam.ie.

Fiberglass vs Cellulose vs Spray Foam

Fiberglass Insulation;

Fiberglass insulation comes in rolls or batts of insulation which can’t be used to insulate small areas, gaps or crevices. It can also irritate the mouth, eyes and respiratory system. Because of this, it should not be used in occupied areas. Fiberglass insulation can last from 10 to 25 years if it remains dry. Fiberglass insulation is useless once it becomes wet. Although it is a cheap source of insulation, it has a relatively low R value. Standard fiberglass blankets and batts have an R-value between R-2.9 and R-3.8 per inch.

You can read more about it on the Wikipedia page, found here.

myfoam infographic

Cellulose Insulation;

Cellulose insulation is comprised of recycled newspaper which has been treated to make the insulation fire retardant. It is three times heavier than fiberglass insulation. There has been some concern in the past regarding offgassing and the unexplained emission of ammonia and a strong odour. You can read about this in a report published by SCI Engineering, here. Cellulose insulation has a lifetime of 20 to 30 years if it remains dry. Wet-spray cellulose is applied damp. This does not affect its insulative properties. If it becomes inundated with water however, it can become extremely heavy and cause slumping. This leaves sections of the wall or ceiling unevenly filled. Cellulose insulation can act as a mild sound barrier. It has an R-value similar to that of fiberglass. Loose fill cellulose has an R-value between R-3.2 to R-3.8 per inch. Dense-pack cellulose insulation has an R-value of approximately R-4.0 per inch.

You can read more about it on the Wikipedia page, found here.

Spray Foam Insulation;

Spray foam insulation expands to fit the environment. This guarantees an airtight seal, unlike fiberglass or cellulose insulation. Once it dries the foam does not emit any particles, fibres or vapours. This ensures it is perfectly safe to install in occupied areas. Spray foam insulation can last up to 80 years with correct installation and caretaking. Spray foam insulation can add structural integrity, improving shearing and racking strength by up to 300%. It also acts as an efficient sound barrier to external noises, as well as internal machinery. Closed-cell insulation stops air and moisture, whereas open-cell foams are permeable to moisture and impermeable to air. Closed-cell spray foam insulation has an R-value of approximately R-6.5 per inch.


You can find a list of benefits here.


If you are more interested in external insulation please click here.

Container Insulation

Here at MyFoam, we provide container insulation for containers of all shapes and sizes nationwide. We use Synthesia approved spray foam insulation which has been certified with the NSAI.

We have garnered plenty of experience providing container insulation across the country. Our professional team are ready to help you.

container insulation


Using our spray foam insulation in containers can drastically improve the R-value of the container. The interior will remain dry and warm. Spray foam insulation has plenty of benefits, you can find a concise list of them here.

Containers have always been popular for storage, however in the past few years they have become a popular source of shelter. Homes and offices are being constructed out of containers all around the globe. You may have heard about the container home which was built in Ringsend recently. The Irish Times wrote an article about it. We provided the spray foam insulation which was necessary to ensure these containers were habitable and perfect for their new use.

We recently analysed the trend of shipping containers homes. You can find that analysis here.

But why such a sudden surge in popularity? Shipping containers are extremely cheap to buy. They usually cost somewhere between €1500 and €2500 depending on the condition of the container. These containers were built to last. They are often waterproof, fireproof and incredibly strong. They conform to building regulations with ease. A building project using shipping containers is oftentimes much quicker than a conventional build.

Before and After

To the right you will find photos of a job we recently completed for Leitrim County Council. You can clearly see the difference between the before and after pictures. With our Synthesia approved spray foam insulation these containers now offer dry, warm storage.


We offer extremely competitive prices here at MyFoam, alongside a nationwide service. If you would like to get a quote feel free to email info@myfoam.ie or fill out our contact form which can be found here.

container without spray foam insulation
spray foam inside container

What are U-values?

What is a U-value?

A U-value is the measure of the rate of transfer of heat. This is not the same as an R-value which is the measure of how resistant a material is to the transfer of heat.


Myfoam insulation truck

A U-value is measured in W/m^2K – Watt/(Metre squared)(Kelvin).

A U-value is the reciprocal of the corresponding R-value. If the R-value is 2, the U-value will be 1/2 or 0.5. If the R-value is 5, the U-value will be 1/5 or 0.2.

The higher the R-value is the lower the U-value is. This confirms the relationship between R-values and U-values. If the material is more resistant to the transfer of heat (high R-value), it will transfer heat as a lower rate (low U-value).

There is no need to focus on both U-values and R-values as they go hand in hand. If you focus on increasing the R-value of insulation materials in your home you are guaranteed to have a decreased U-value.

Why are U-values important?

Building regulations for Government grants require that U-values for houses must not exceed the following;

       Roof   0.4 W m-2 K-1
       Walls 1.1 W m-2 K-1
       Floor  0.6 W m-2 K-1

SEAI Grants

You could receive up to €4500 – not bad, right?

These grants are only available on homes built before 2006, and you must use an SEAI registered contractor for all works. Luckily, we are an SEAI registered contractor. We even provide a nationwide service.

You can find more about SEAI grants here.

If you would like to find out more about the grants available with the Better Energy Homes Scheme feel free to contact us on 1800 911500, or by email at info@myfoam.ie. We also have a contact form available on our home page. Our excellent team provide professional guidance from the outset and throughout.

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