You can compensate for this stacking effect and achieve the desired total r value by adding about one extra inch of insulation if the old insulation is fiber glass or about 1 2 inch if the old insulation is rock wool or cellulose.
Desired r value for attic.
Calculate the square footage of the attic you re insulating.
Once determined subtract the current r value from your desired r value to get the r value you need to add.
Recommended home insulation r values.
Subtract that amount from the desired r value for your home s zone to.
This zone s recommended r value for an uninsulated attic is r30 to r60.
Be sure to carefully follow the installation instructions to get the desired insulation r value.
R value measures how well certain building insulation materials can resist heat.
This calculator is to be used as an estimating tool only.
Input length width and desired r value of the area to be insulated.
Click the button to calculate the depth in inches and pounds of total insulation required for this job.
An attic with too little insulation will waste energy and money in both winter and summer.
When determining how much insulation you need don t guesstimate calculate.
This effect is most important if the new insulation is more dense than the old insulation.
Determining your attic insulation needs.
It is generally better to insulate to a higher r value than the minimum recommended level.
Insulation level are specified by r value.
Know exactly how much you need with our project calculators.
Of inches to determine your existing r value.
The homeowner could then check table 1 to find several choices.
An r value of 40 to 50 rsi seven to 8 8 is recommended for attic insulation in most parts of u s.
Find the recommended r value for attic insulation in your area.
If the existing attic floor insulation has an r 11 insulation value then an additional r 27 would be needed to bring the attic floor insulation up to the level recommended for that house.
Instructions on the product where current r value is listed will guide you through estimating the number of packages to buy based on the number of square feet you re insulating and the desired r value.
The higher the r value the greater the insulation performance.
Measure the length and width of the attic then multiply those numbers to get the total square footage.
You will need a higher r value of insulation if you live in the northeast than if you live in southern california.
There are many ways to retrofit a home with fiberglass and.
The higher the r value the better the thermal performance of the insulation.
Where you live different climates require different insulation r values.
