Standard Wall Insulation R Value

The ideal attic insulation r value is different than the ideal wall insulation r.

Standard wall insulation r value.

For instance if you have a material with an r value of 12 attached to another material with an r value of 3 then both materials combined have an r value of 15. R value is the temperature difference per unit of heat flux needed to sustain one unit of heat flux. For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3. In the context of building and construction the r value is a measure of how well a two dimensional barrier such as a layer of insulation a window or a complete wall or ceiling resists the conductive flow of heat.

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. R value level depends on a number of things such as the type of material its density and thickness. Basics of faced fiberglass insulation from r 13 to r 19. Recommended insulation levels for retrofitting existing wood framed buildings.

For example a wall with 3 fiberglass batting r value of 10 8 11 9 may have an overall r value of nearly 14 because of siding sheathing and drywall. Does not consider presence absence of reflective barriers. As a benchmark one inch of solid wood has an r value of 1. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system.

The r 0 87 value for the first value in this air r value table subsection. Existing 3 4 inches of insulation. In construction the r value is the measurement of a material s capacity to resist heat flowfrom one side to the other. Does not consider internal convection effects.

See the department of energy s doe ranges for recommended levels of insulation below. Air gap or air film 3 4 air space insulating properties. R stands for thermal resistance. The r refers to absolute thermal resistance.

While wall insulation is limited by the width of the studs different materials provide higher or lower r values. 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. Add insulation to attic. R value is a standard unit of measurement for determining among many things how effective your insulation will be.

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. Note from this chart that the ideal r value differs for each part of your home. In simple terms r values measure the effectiveness of insulation and a higher number represents more effective insulation. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

Fiberglass batts for standard 2 4 walls are now available in low medium and high density products that range from r 11 to r 15. Higher r value numbers mean that the insulating material resists the cold or heat from the outside better. Thickness density and type of materials are some factors that contribute to r value.