How Much Insulation for Ground Floor Construction?

Insulation Features

• Ground floor construction can use a variety of different insulation choices. Blanket insulation, in the form of rock wool, fiberglass or mineral wool, is a continuous roll that is unwound across a flooring's underside. Blown-in loose fill insulation is sprayed under a flooring system. Typically, blown-in insulation is in the form of polyurethane foam, cellulose, rock wool, or fiberglass. As an alternative, reflective insulation uses foil film or cardboard for filling in under flooring systems.

Qualifying Insulation

• Determining the amount of insulation needed for a ground floor construction depends on the surrounding region's temperature extremes. The United States Department of Energy has divided the country into six particular regions, based on yearly temperature variations. Colder areas, such as those to the extreme north, must use denser insulation across the entire ground floor, including any small corner crevices. In contrast, warmer regions, such as Hawaii, require less dense insulation since local temperatures do not vary extremely throughout the year.

Density Determination

• Insulation quantities are based on an R-value. An R-value represents the insulation's resistance to heat and air flow. A higher R-value indicates that the insulation resists more air and heat flow than a lower value. For example, Hawaii requires a R-value of R11 for flooring insulation. However, Alaska should use R25 insulation for floors. Alaska's high R-value reflects the extreme regional temperatures, as opposed to Hawaii's mild climate. Ground floor construction must use these regional guidelines for insulation installation, producing an energy efficient building.

Installation

• Ground floors using floor joists, or beam supports, must have all crevices filled with the specified regional insulation. Any openings within the insulation provides a pathway for heat loss. Verify that all joist crevices are filled, or covered, completely with insulation. In contrast, ground floors with a concrete slab must have insulation installed beneath the slab form. Heat is easily lost across the slab and into the ground without a full coverage insulation installation.

Benefits

• According to CED Engineering, homes typically use 50 to 70 percent of energy costs toward heating and cooling. Proper insulation installation and R-value choice will effectively curb energy costs over time.