# How do I calculate the R-value in my attic?

## How do I calculate the R-value in my attic?

To find the R-value of the existing insulation in your attic, multiply the number of inches of insulation by the R-value for your particular type.

## What is code for R-value in an attic?

Depending on where you live and the part of your home you’re insulating (walls, crawlspace, attic, etc.), you’ll need a different R-Value. Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces.

**What is the R-value of blown in attic insulation?**

2.2 to 2.7 per inch

Blown-in. If you are insulating an attic or wall cavities, blowing the insulating material in using pneumatic equipment ensures maximum coverage. You can also apply it over existing insulation. Blown-in fiberglass has an R-value of 2.2 to 2.7 per inch.

**Which insulation has the highest R-value?**

Answer Wiki. Vacuum insulated panels have the highest R-value, approximately R-45 (in U.S. units) per inch; aerogel has the next highest R-value (about R-10 to R-30 per inch), followed by polyurethane (PUR) and phenolic foam insulations with R-7 per inch.

### How do you calculate the value of R?

The equation for determining R-value is as follows: R-value = temperature difference x area x time ÷ heat loss. The temperature difference is expressed in degrees Fahrenheit , the area in square feet, the time in hours, and heat loss in BTUs .

### How do you calculate the are – value of insulation?

One way to calculate the R-value of existing insulation is to measure it with a tape measure. Place the tape measure down and touch the ceiling board to get the height. For most insulations, including fiberglass and cellulose , every inch of insulation is roughly equal to an R-value of 3.5.

**How to determine the R-value of insulation?**

Calculate the R-value of your attic insulation by multiplying the measurement you took by a factor based on the type of insulation you have in the attic. The Oak Ridge National Laboratory recommends using a factor of 2.5 for loose fiberglass; 2.8 for rock wool; 3.7 for cellulose; and 3.2 for fiberglass batting.