R Rating For Attic Insulation

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.

R rating for attic insulation.

Insulation typically works by preventing conductive heat flow and r value measures how effective it is at this. Warmer climates only require an r 38 or higher or about 12 or more. Cellulose insulation r value is r 3 2 to r 3 8 per inch. You can get high performance batts rated as high as r 4 3 per inch.

Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. The r actually stands for resistance of heat flow that is. Standard batts have an r value of r 2 9 to r 3 8 per inch. 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.

Batt insulation can be made of fiberglass mineral wool plastic fibers or natural fibers. Houses in a cold climate should have a minimum of r 49 in the attic which is equivalent to approximately 16 of fiberglass insulation. Existing 3 4 inches of insulation. R value is a rating system used for insulation that measures its degree of insulating power.

The higher the value the more insulating ability the product has. Add insulation to attic. First things first you need to go up into your attic inspect the condition of the insulation and calculate the current level of insulation. Cellulose insulation is a type that is typically blown into place.

R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. R values vary based on. 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. 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.

The overall r value of a wall or ceiling will be somewhat different from the r value of the insulation itself because heat flows more readily through studs joists and other building materials in a phenomenon known as thermal bridging. Recommended insulation levels for retrofitting existing wood framed buildings. For example insulation that is compressed will not provide its full rated r value. To achieve a higher attic insulation r value simply add another layer of insulation.

Inspecting your attic insulation. As a benchmark one inch of solid wood has an r value of 1. 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.