How Thick Should Blown Insulation Be In Attic

They come with or without a paper or foil facing that acts as a vapor barrier.

How thick should blown insulation be in attic.

When blown into attics and wall spaces loose fill fiberglass offers an average r 2 5 thermal value per inch the higher the number the greater the insulating effect. Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. When adding additional insulation you do not have to use the same type of insulation that currently exists in your attic. This calculator is to be used as an estimating tool only.

First things first you need to go up into your attic inspect the condition of the insulation and calculate the current level of insulation. Divide the desired r value by the r value per inch stated on the label. To add to the. Most attics are insulated with blown in loose cellulose r 3 5 per inch blown in loose fiberglass r 2 5 per inch or fiberglass batts r 3 2 per inch.

To insulate to r value 50 with an r value of 3 5 per inch you will need 50 divided by 3 5 or about 14 inches. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. Cellulose is recycled newsprint treated with a fire retardant. For loose fill cellulose this translates to a total depth ranging from 8 inches.

It is not uncommon to see 15 to 20 of insulation in a well insulated attic. The thicker the better. The higher the r value the better the thermal performance of the insulation. You d need a thickness of.

Inspecting your attic insulation. Add the right kind of insulation. This flexible insulation material is most often packaged in rolls that come in various thicknesses and standard widths usually 16 inches and 24 inches to fit between joists or studs in a house s framing. The insulation in your attic should be at least 12 thick.

Your attic should have a certain amount of insulation in it and the recommended level of insulation for your attic is dependent on where you live. In temperate coastal areas such as zone 3 attic insulation of at least r30 up to a maximum of r60 is recommended. Input depth of existing blown in insulation in inches. Click the button to calculate the approximate r value for this job.