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  • Asieh Ansarihamedani

R-Value of Spray Foam Insulations

Spray foam tends to create a seal that prevents air movement in and out of your home. And that's precisely why it is so effective in maintaining a constant temperature in your house.

So, what's this spray foam insulation R-Value?

R-Value of Spray Foam Insulation

R-Value refers to the measurement of the thermal resistance of any insulation material. And thermal resistance is the ability of a material to resist the transfer of heat or its loss due to conduction.

Suppose any hot or warm material comes in contact with the cold material. In that case, heat will travel from the hotter material to the colder surface. Therefore, the heat transfer resistivity of insulation material is its thermal resistance.

Cellulose and fiberglass only focus on the prevention of this conduction. At the same time, spray foam emphasizes the stoppage of this conduction and convection and air movement.

The R-Value of a spray foam insulation depends upon the product, its manufacturer, and various other variables. For example, the R-Value of open-cell spray foam insulation ranges between 3.6 to 3.9 per square inch.

This R-Value is normal for any spray foam. On the other hand, the R-Value of closed-cell spray foam insulation ranges from 6 to 7 per square inch.

Medium-density spray foams come with R-Values that range between these two extremes. The R-Value of medium-density spray foam insulation ranges between 4.1 to 5.7 per square inch.

Factors Influencing the R-Values

Not all spray foams are the same, and this is why there is a difference between the R-Values of open and closed-cell spray foams. The R-Value of spray foams is influenced by three major factors; the foam type, its age, and how well it handles moisture (moisture resistance).

  • Foam type

Foam-type insulations affect the R-Value based on the overall construction. Open-cell foams are light, and that is why their R-Value is low. On the other hand, closed-cell foam is thicker and has a higher R-Value. This is because the heat takes much longer to transfer through thicker insulation that features denser composition.

Medium-density spray foams are not as thick as closed-cell foams, but they are thicker than open-cell foams. As a result, they offer better heat resistivity than open cells but a reduced heat resistivity than denser closed-cell foams.

  • Material age

Spray foam age is also an integral factor here. Some brands of these spray foams can wear out and break down much quicker with age. But there are spray foams that don't disintegrate with time as quickly as others. Therefore, they maintain their R-Values for a much longer period.

Medium density spray foam ages better than open cells. They maintain their R-value for longer periods than open cells. But they tend to disintegrate over time faster than the thicker closed cell foams.

  • Moisture permeability

If spray foam is saturated more in water and moisture is present within its pores, it will conduct heat and reduce the overall heat resistivity of the insulation. So, the spray foam insulation gets a reduced R-Value.

This happens more frequently with open-cell spray foams because it is more moisture permeable. Closed-cell spray foams are impervious to moisture. They don't allow moisture to move through the pores. Therefore, its R-value gets influenced as much.

Medium-density spray foams are more moisture-permeable than thicker closed-cell ones but more moisture impermeable than thinner open-cell spray ones. Thus, they offer a good bit of balance between the two extremes.

Spray Foam Insulation R-Value in Comparison to Other Insulations

In the comparison of spray foam insulation with cellulose and fiberglass, air seal is a huge game-changer. This is because fiberglass and cellulose cannot stop air, and R-value here only refers to the way of conduction. Therefore, fibrous materials have the upper hand here.

Heat can travel much quicker due to air movement or convection than conduction. And this is where that air seal comes in because cellulose and fiberglass still allow air to travel through them. Foam insulation doesn't allow that to happen.

Therefore, in addition to conductive resistance, an air seal is also important. You won't be able to stop heat transfer if you're not stopping the air travel.

Perspective and Performance - Building Code vs. R-Value

When talking about the R-Value perspective and insulation requirements, it all boils down to the location where you live. If your location falls into climate zones that tend to get colder in winter, you will have to look at your area's building code and how much insulation it allows.

This code will also allow you to focus on certain areas in your home where you can go for more insulation. Therefore, you need to balance the R-Value that you need according to the building code requirements.

For this, you will need to assess your home's insulation performance over time in different seasons. You can either do it yourself or hire a professional service to run an R-Value audit on your home.

Book An Assessment for Your Home Today

If you are looking for the best services in town when talking about R-Value assessments, you don't need to go anywhere.

Get in touch with our professionals for a complete report on how much spray foam insulation is required for your home.

We will run a few tests, including the airtightness test, home energy audit, and R-Value test and will provide you with a complete report on how your house scores in terms of overall insulation and energy efficiency.

Our team of experts understand everything associated with spray foam insulation and air sealing, and we specialize in medium-density spray foams. So, pick up your phone or drop us an email for an assessment today.



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