Types of R-Value House Insulation


The power of insulation is stated in R-value and is typically listed per inch. Each type of insulation has unique properties that make it suitable for a particular situation. Expanding foam insulation, for example, is best suited for tight spaces where there are a lot of nooks and crannies to fill.


  • Fiberglass insulation typically comes in rolls. The rolls are sized to fit between the studs of exterior walls, so they're usually 16 to 24 inches wide. Made of long strings of material that are bound together, rolled fiberglass insulation is the most popular form of insulation in the United States. Rolled fiberglass or batt insulation offers an R-value of around 4 units per inch. Rolled fiberglass insulation comes in two primary forms: faced and unfaced. The paper facing on the rolls is designed to seal out moisture, which can be easily trapped in the porous fiberglass.

Concrete Insulation

  • Heat-treated concrete insulating blocks are rapidly becoming one of the most efficient insulating materials in the world. The highly porous concrete is filled with either polystyrene or polyurethane foam, and the concrete bonds to the filler. The concrete alone offers an R-value of 1 point per 1-inch thickness. The polystyrene interior provides 2 units of R-value per inch. Air makes up as much as 80 percent of the concrete's volume and the blocks are joined with mortar, allowing very little air to flow between the blocks.

Rigid Foam

  • Rigid foam insulation is formed into boards that are used to insulate everything from roofs to flooring. Made of polystyrene, these boards resemble sheets of plywood and come in different thicknesses. They offer an R-value that ranges from 4 to 4.5 per inch. The boards are nearly always faced with a vapor barrier since they are extremely absorbent. The only time that the boards go unfaced is if there is no chance of water penetration into the insulated space.

Expanding Foam

  • Expanding foam insulation is designed to fill even the smallest spaces. When it's first sprayed, the foam is a thin liquid. It then begins to expand and harden, filling the space. The foam can be composed of many materials, but the most popular are phenolic or polyurethane. The R-value for expanding foam insulation, because it can fill even the smallest voids, can be as high as 8 units per inch.


  • Foil insulation is made to be easily installed and is very lightweight. Reflective insulation often covers the front of insulating foam panels in order to better protect against radiant heat. One downside to reflective insulation is that it conducts electricity easily, meaning that anything covered with reflective insulation must be kept far away from wiring. The R-value for reflective insulation is often governed by the material it's coating.

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