R60 Insulation Thickness Guide For Fiberglass, Spray Foam, Cellulose & Wool

The R-value of a material determines its ability to resist thermal energy. This value is further categorized into different standards that define it better such as R20, R30, or R60. Such standards help identify the overall resistance power of a material. For example, an insulative material having a rating of R30 would be less effective as compared to a material having R60. To put it straight, the higher the value, the more powerful insulation you’ll get. If you’re looking to go for an R60 rating, you’ll need to put up a certain volume of insulation material to achieve that. Different materials require specific levels of thickness to make their guard reach R60. In this read, we’ll be comparing some popular insulation materials and how much of them would it take to get R60 insulation.

Different places require different R-value ratings. For instance, if you’re residing in Ontario and want your attic insulated, you’ll need an R-50 or R-60 rating. However, if you’re in California, a lower rating would get the job done due to the region’s moderate climate. Thus, it is best to research first whether R60 is fit for you or not. Let us now continue and take a look at the volume of different materials along with their thickness measurements to make it to R60.

R60 Required Thickness of Insulation Materials

When it comes to insulation materials, you have a wide variety to choose from. Below are some of the most commonly preferred materials and the thickness they need to adhere to the R60 bar. 

Insulation MaterialThickness Required for R60
Fiberglass (Batts)20-26 inches
Fiberglass (Loose-fill)16-20 inches
Spray foam (Closed-cell)6-10 inches
Spray foam (Open-cell)10-14 inches
Cellulose (Loose-fill)15-20 inches
Stone wool (Batts)12-16 inches
Stone wool (Loose-fill)8-12 inches

Note that these values may slightly vary from the given data since R-value is calculated by taking several factors into account, such as the quality of the material. 


Fiberglass insulation is one of the most widely preferred types of insulation out there. It usually comes in the form of either batt (sheets) or loose-fill that is blown with the help of a blower. Made through tightly packing glass particles, fiberglass can filter out much of the energy that gets into the building. This includes thermal energy and soundwaves as well. When it comes to fiberglass batts, the sheets usually come in the size of 16×24 inches boasting around 2.5 R-value for every inch. However, if you’re looking to go for R60, you’ll need around 16-20 inches of thickness. As for loose-fill fiberglass, around 16-20 inches of thickness would be sufficient to achieve R60 since loose-fill generally has a higher rate of effectiveness as compared to fiberglass batts.

Spray Foam

Ideal for filling tight gaps and hard-to-reach spaces, spray foam insulation is sprayed through a blower. It is a polyurethane spray that expands quickly as it makes contact with the surface. Due to its hyper extensive properties, spray foam is best for cutting off airflow, especially from those tiny spaces where air might get through the walls. As far as its R-value is concerned, it varies according to the type. You’ll find two main kinds of spray foam out there:

Open-cell spray foam

Open-cell spray foam is a lighter version of spray foam that is composed of a less-dense mixture as compared to close-cell. It is best for light-duty fillings between gaps and spaces. You’ll need around 10-14 inches of thickness for open cell spray foam to achieve an R60 rating.

Closed-cell spray foam

Closed-cell spray foam is the denser version of spray foam that tightly locks itself against the surface and prevents airflow to a great extent. Ideal for overall application on walls and attics, the closed-cell spray foam also blocks out soundwaves. To make its insulation go up to R60, a thickness of 6-10 inches would be needed.


Cellulose is made of recycled wood and brings a significant amount of insulation to the table. The composition mainly consists of old newspapers, lightwood, and fire retardants. Together these elements make up fibers that act as a barrier between the building and the weather. Much like fiberglass, cellulose is capable of trapping airflow and countering mold. Furthermore, cellulose typically comes in the loose-fill form. Therefore, a blower is needed for installation and application. As for its R-value, you can expect it to be 3-4 per inch. If R60 is your goal, you would need around 15-20 inches of cellulose thickness.

Rock Wool

Also known by the name mineral wool, rock wool comes into being through molten rock. Initially, minerals go through an extreme heating process that leads them to their melting point. Afterward, these minerals are spun like cotton candy resulting in a fine wool texture through which rock wool is made. These thin fibers are given the shape of batts and are used for insulating buildings. Two of the things that make rock wool stand out are its ability to heavily reduce the number of soundwaves that try to pass through the insulation, the second is its high resistance against fire. Due to its sound-blocking properties, rock wool is usually the most widely preferred option for sound insulation in recording studios. The material gives you a significant amount of R-value with 3-3.5 for every inch. In order to go for R60, aim for around 12-16 inches thickness of rock wool batts and for 8-12 inches for blown wool.

Further reading: Rockwool R value

Should You Go for R60?

As you can tell by now that the R60 rating of any insulation material is quite high. It can block out much of the airflow that tries sweeping into the building. Due to its extreme thickness requirements, loads of insulating material would be needed to fulfill R60 standards. Not only will this be highly costly, but it would also take a good while to set up such dense walls of insulating material. Therefore, it is highly recommended to call a professional and consult whether the building is truly in need of such high R-value-based insulation or not. Whether it’s your home or office, only a professional would be able to analyze the structure’s insulation needs according to the regional weather conditions and give a final judgment after thorough calculation. 

Is There Such a Thing as Over-insulation?

This is a commonly asked question that often comes from those looking to achieve the highest levels of insulation. To put it straight, the answer is yes, you can over-insulate your house. Since the whole purpose of insulation is to keep the internal air trapped inside and block external airflow, too much insulation would result in moisture building up. This will eventually lead to the growth of mold and decay of your costly insulation material. Furthermore, you’ll feel suffocated inside and you’ll probably regret spending your life savings on insulating your house more than you should have. So, that is why it’s best to seek a professional’s advice before taking things forward.


There’s no denying that an R60 rating can do wonders for your insulation needs, but bear in mind that most people settle for R30 and don’t go beyond unless they really have to. Nonetheless, now you know the thickness common insulation materials need to fulfill R60 standards. We hope this information benefits your research.

Additional reading:

You can also use my insulation thickness calculator to find out the thickness required for different insulation materials for your desired R-value.

Charles John

Experienced HVAC technician with 8 years of experience in the industry. Capable of handling all sorts of heating and cooling equipment as well as proficient in operational management, construction-related techniques such as preventative maintenance, electrical troubleshooting and AutoCAD

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