Roof Insulation Ratings

Having the correct amount of attic insulation can help you maintain a comfortable temperature throughout your home and help save money on your energy bills plus prevent major issues like ice dams in the winter.

Roof insulation ratings.

Insulation level are specified by r value. Measure the depth of your current insulation. The greater the r value the greater the resistance to heat transfer and the greater the insulating effect and subsequent energy savings. R 38 is the industry standard and the minimum thickness for r 38 is 12 inches.

Calculate additional insulation needed. If your current insulation is only 5 inches deep you ll need to add seven inches of insulation to achieve the 12 inch r 38 rating. Insulation ratings are measured in r values per inch of thickness. An r value tells you how well a type of insulation can keep heat from leaving or entering your home.

In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and an inch of blown cellulose in an attic has an r value of 3 2 3 7. Measure the area needing insulation. The r value is a measure of the insulation batt s resistance to heat flow also known as thermal resistance. 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.

The r value per inch for different types of insulation varies depending on the. The table below shows what levels of insulation are cost effective for different climates and locations in the home. Insulation r values vary based on the type thickness and density of the insulation material. R value is a measure of insulation s ability to resist heat traveling through it.

Improved insulation is a good step toward improving building efficiency particularly since the atlanta based american society of heating refrigerating and air conditioning engineers ashrae increased minimum roof insulation levels in 2007 in its standard 90 1 the first increase in 18 years and if that isn t enough to spur someone into action. A recent mckinsey co. The higher the r value the better the thermal performance of the insulation. If you think you re among the 90 of us homes that are under insulated 1 performing a simple insulation inspection will help you determine your insulation needs.

As a benchmark one inch of solid wood has an r value of 1. See the department of energy s doe ranges for recommended levels of insulation below.