Blown In Insulation Calculator: How Much Do I Need?

How much blown-in insulation do you need for your attic and walls? Here is an easy calculator to find out that.

Blown Insulation Calculator

To get the volume of blown-in insulation needed, enter the length and width of the floor or wall (where you put the insulation), and the R-value required. Then this calculator will tell you how many pounds of insulation you need and in what thickness you need to lay it to get the desired R-value.




Desired R-Value

How much blown in insulation do you need? The math

You need 1.3 pounds of blown insulation per cubic feet of insulating area. The amount of insulation required depends on the length and width of the area to be insulated as well as how thick the insulation needs to be laid to reach the desired R-value.

As you know, the R-value of blown in insulation is 3.25 per inch. So if you want an R-value of 32.5, then you need to lay the insulation in 10-inch thickness. This thickness is used in addition to the length and width of the attic to calculate the blown insulation you need to buy.

blown insulation calculator

How can this calculator help you?

This calculator will come in very handy as figuring out the math on how much blown-in insulation you need is not always easy. And if you end up with the wrong R-value, you will not be able to enjoy the results you expect. 

Before you use this calculator, you will need to know the desired R-Value you want to obtain and the dimensions of the surface you want to insulate. Once you have this essential data, insert the length and width in feet and inches, along with the R-value you need, and hit the “Calculate” button.

Given below is a table listing the recommended R-values for attics and walls based on different climate zones. If you are not sure what R-value you need, feel free to choose it from this table;

Climate ZoneRecommended R-value (Attic & Walls)
1R30 to R49
2R30 to R60
3R30 to R60
4R38 to R60
5R49 to R60
6R49 to R60
7R49 to R60
8R49 to R60
Recommended R-values for different US climate zones

When you receive the result, you will get the quantity of insulating material and how thick they need to be.

How much blown insulation for 1000 square feet

Using the above calculator, and assuming that you need R60, you will need approximately 2050 pounds of blown insulation. You must lay this insulation in 18.5-inch thickness to get the required heat resistance.

General Info

What is blown in insulation?

The blown-in insulation uses materials such as fiberglass, cellulose, and others with similar density, thickness, and texture. The materials used in blown-in insulation should be easy to fit in tight spaces such as between ducts or wires and in corners that might be difficult to access for other types of insulation. 

Where can you use blown insulation?

Blown insulation is commonly used in attics, but you can use it in any other space of your home as it will be just as efficient.

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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