Home Wall R-Values

Rigid Wall Insulation

Introduction:

Proper home insulation is critical if you want to save on energy cost and have a comfortably warm home. The walls are the most difficult part of the home to insulate. The wall insulation is expressed in terms of R-value which indicates the efficiency of the insulation of the wall.

The total R-value of the walls is made up on the building material such as the outside sheathing, the inside wall board, the insulation in the walls, and the studs that frame the wall.

The insulation R-values of the individual wall framing materials (studs and sheathing) do not give an accurate measurement of the average for the whole wall. The following are the 3 methods commonly used to measure the home wall R-values of your home.

The clear wall R-value:

The clear wall R value is the value of a wall with just the studs. This doesn't include windows, doors and the exterior corners.

Center of Cavity R-values:

The center cavity wall insulation R-value is the estimate of cavity space between the studs.

Complete wall R-value:

The complete wall R-value is the estimation of R values for both the clear wall and the center of cavity. It takes into account additional materials such as the windows, doors and exterior corners. The complete wall R-value is generally the most reliable method for determining R-values for insulation of walls.

Facts about the R-value of wood wall studs:

Approximately 12% of the home is not insulated properly due to the wood framing. The poor R value of wood can create a cold area in the insulation where the wood stud meets the sheetrock. The cold spots can compromise the insulation and lower the effective average R-values of the complete wall. In addition to the poor R-values of wood lowering the R-values of the wall, a cold spot may lead to condensation problems in the wall. Moisture can condense through the wall studs, which generally have the lowest insulation R-values, and the other framing materials of the home. If moisture does get into the wall cavity condensation can begin where the cold R-values of wood studs meet the sheetrock.

The R-values of wood wall studs are linear and are measured in terms of inches. However, the wood wall studs generally lower the R-values of the wall.

The R-values of wood is 1.25 per inch. The R-value of framing studs is as follows:

A 2X6 wall stud R-values is measured as, 5.5" X 1.25. The R values = 6.875.
A 2X4 stud wall studs R-value is measured as, 3.5" X 1.25. The R-values = 4.375

You can increase the R-value of your home and help protect against moisture entering the walls by installing rigid foam insulation sheathing to the exterior of the walls. Rigid insulation panels can be used for ceilings, floors, walls, and roofs. Standard panels are sized in 4x8 foot sheets and are one to two inches thick. The insulation material consists of polystyrene, polyurethane, polyisocyanurate that has an R-value between 4 and 9 depending on the thickness.

Rigid insulation is high strength, easy to work with and is very effective at increasing the home wall R- value by eliminating cold spots in your home and keeping out moisture.

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