Asked by: Bahadur Lindquist
home and garden indoor environmental quality

How thick should blown in insulation be?

Last Updated: 6th June, 2020

R-Value is a measure of insulation's ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

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Accordingly, how many inches of blown insulation is r30?

In temperate coastal areas such as Zone 3, attic insulation of at least R30 up to a maximum of R60 is recommended. For loose-fill cellulose, this translates to a total depth ranging from 8 inches up to 16 inches.

Furthermore, what is the R value of 12 inches of blown insulation? An R-value is also calculated per inch of width. Therefore, a three-inch-thick board has an R-value of 3. Blown fiberglass installed in the attic has an R-value of 2.2 per inch, so 12 inches of it would give you an R-value of 26.4 in your attic installation project.

In this way, what is the R value of 10 inches of blown insulation?

R-value of Materials and Depths
Material R-value/in 10"
Mineral Wool blown (wall) 3.1 - 4.0 31.0 - 40.0
Cellulose blown (attic) 3.2 - 3.7 32.0 - 37.0
Cellulose blown (wall) 3.8 - 3.9 38.0 - 39.0

Is blown in insulation better than rolls?

Batts, or rolls, are large blankets of insulation that are made from either fiberglass or cotton. Blown insulation is accomplished by blowing out chunks of either fiberglass or cellulose from the hose of a blowing machine. The main benefit of blown insulation is that it is a much more consistent type of insulation.

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Can you put too much insulation in your attic?

Without proper ventilation, a home can build up too much moisture, especially in the attic (warm air rises), which can cause mold problems and, overall, lower indoor air quality. This is not to say that if you have mold in your home, too much insulation is the culprit.

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How many inches of insulation should be in an attic?

The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

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How do I know if my insulation is blown?

Cellulose blow-in insulation is constructed out of recycled paper. To determine how much cellulose insulation you need, take the square footage of the space and divide it by either the depth or the desired R-value. Fiberglass blow-in insulation is essentially made up of spun fibers from recycled molten glass.

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What is the going rate for installing insulation?

Cost: The average cost per square foot is between $0.64 - $1.19. So, for a 500 square foot area, your estimate will vary between $145 to $200, if you do it yourself. For a professional job, add between $150 to $300 for labor, and you're looking at around $300 to $500 for 6 hours of work.

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What is the cost of blown in insulation per square foot?

Blown-In Fiberglass Insulation Costs
R-Value Bags Per 1,000 Sq. Ft. Material Cost
R-30 15 $495
R-38 20 $660
R-44 23 $759
R-49 26 $858

Letizia Leña


What insulation should I use in my ceiling?

The most common insulation materials are fiberglass, cellulose and foam. Insulation types include loose fill, batts, rolls, foam board, spray board and vapor barriers. Tip: The type of insulation you need depends on which type is currently installed and the required R-value.

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What is blown in insulation made of?

There are three general types of blown insulation materials currently available: fiberglass, cellulose and rock wool. Fiberglass loose-fill insulation is made glass and sand that are spun or “blown” into fibers. This type of insulation is great for wall cavities and attics.

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How many inches R value?

Comparative Insulation R-Values
Insulation Type: R-Value per Inch:
Fiberglass (batts) 2.9 – 3.8
Cellulose (loose) 3.1 – 3.8
Stone Wool (loose) 2.2 – 3.3
Stone Wool (batts) 3.3 – 4.2

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What is the R value of blown in insulation?

Here are the R-values per inch of the most common types of insulation: Fiberglass (blown): 2.2 – 2.9. Fiberglass (batts): 2.9 – 3.8. Cellulose (blown): 3.1 – 3.8.

Elide Klafke


How many inches is r38?

An R-38 fiberglass batt should be approximately 12 inches thick, while the thickness of cellulose insulation of a finished, fitted product will larger.

Myrtle Cantalejo


Does cellulose insulation lose R value?

Cellulose insulation is the most prone to settling and will undergo a 20 percent loss of R-value due to settling. R-value measures the relative effectiveness of insulation per inch.

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What is the R value of 1 inch Styrofoam?

Also called Styrofoam insulation, this is the least expensive material. It provides R-values that range from 3.6 to 4.2 per inch. Some products have reinforced facing to make them sturdier.

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What is the R value of 6 inches of fiberglass insulation?

Fiberglass Insulation Batts
Fiberglass blankets or rolls provide an R-value of up to 3.2 per inch, so a 6-inch fiberglass batt may achieve an R-value of 19.2, and some high-performance products are rated at R-21.

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How thick is r60 blown fiberglass insulation?

Anywhere from 16-22 is correct. For you see blown cellulose has an approximate average R-value or 3-3.5. We had R60 loose fill blown in for the Green on rebate (and to improve attic insulation of course) and they did 22", with a ruler to show the height.

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How thick is r48 insulation?

Compare all Specifications
Insulation Location Attic Insulation Location Ceiling
Roll or Batt Batt Roll or Batt Batt
Product Length (ft.) 4 ft Product Length (ft.) 4 ft
Faced or Unfaced Faced Faced or Unfaced Faced
Product Thickness (in.) 14 in Product Thickness (in.) 8.25 in

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How many inches of blown insulation is r40?

Blown and batt insulation have different r-values based on depth. R-25 is approx. 7 inches of blown insulation R-40 is 12 inches of blown insulation.

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What is the R value of 2 inches of spray foam?

Open-cell spray foam absorbs and holds water. It has a lower R-value per inch than closed-cell foam and is vapor-permeable. The R-value is R-3.5 to R-3.6 per inch, so filling a 2×4 cavity yields about an R-13.

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How much blown insulation do I need calculator?

Example Calculation
= 12 Area = 10 * 6 = 60 square ft Required depth to achieve R value needed = R 12 / R 3.6 = 3.3 inches Volume needed = 60sq ft * 0.275 (3.3 /12 converting to decimal ft) = 16.5 cubic feet You would need one bag in this case. Note: the cost is based on rounding up the number of bags needed.