The top 10 most frequently asked insulation questions

What is R-Value?R-value refers to insulation’s resistance to heat flow. Tiny air pockets trapped in the insulating material resist the passage of heat & heat gain in the warm summer months and heat loss in the colder winter seasons. The higher the insulation’s R-value, the greater its insulating power.
Which R-Value Should I Choose for My Project?Refer to the United States Department of Energy recommendations or State Energy Code to determine the right R-value for your project in this climate.
Do Higher Insulation Levels Create Condensation Problems?No. Insulation is not a source of moisture nor does it cause condensation. Ventilation and Vapor Retarders are used to control moisture.
What is a Vapor Retarder?A Vapor Retarder is a material used to slow down the transfer of moisture from one area to another. They are used to help prevent condensation problems within building assemblies. A kraft paper-faced Vapor Retarder with a thin layer of asphalt is adequate for most applications and is available almost anywhere.
How Do I install a Vapor Retarder?The Vapor Retarder, or the Kraft paper side of the insulation should always be installed facing the warm side (the interior) of your home. This applies to attic, side wall, floor, or basement insulation projects. Simply staple the flange of the Kraft paper to the inside or face of the stud. When stapling is necessary in cathedral ceiling projects, always face-staple to maintain the necessary 1� ventilation space.
What is the Most Effective Way to Cut Insulation?Lay the insulation on a board with the Kraft facing down, if the batt is faced. Lay a yardstick (or 2 x 4) over the area of insulation to be cut. Press your straight edge down hard and cut with a utility knife, using the straight edge as a guide.
What Should I add to an Attic that Contains Existing Blanket or Loose-Fill Insulation?Always use unfaced � with no vapor retarder � blanket insulation when adding another layer to existing insulation. We recommend R-25 MIRAFLEX Insulation. Be sure to refer to the Department of Energy recommendations or State Energy Code to choose the right R-value to compliment your existing insulation. Also, ensure that one square foot of free vent area is available for each 150 square feet of attic floor area. To add ventilation, consider a combination of soffit and roof vents.
If I install a Vapor Retarder in My Attic, Do I Still Need Ventilation?Yes. Even with a good Vapor Retarder, proper ventilation is considered essential to prevent damaging condensation and to provide under roof deck cooling in the summer months. Eave vents � openings at the roof overhang � combined with a ridge vent, roof vent or gable vents, are effective ways to create a positive movement of air in and out of the attic.
How Do I Know What Width of Insulation to Purchase?Most construction practices call for the width of both sidewall and attic framing members to be either 16� or 24� wide. Owens Corning has product widths to meet both of these dimensions.
Can I Increase the Effectiveness of Fiber Blankets by Squeezing More into a Smaller Space?No. Compressing thick fiber glass blanket insulation into a smaller wall space will not increase your insulation�s efficiency. Fiber glass insulation works on the principle of trapped air pockets. By compressing the insulation, you decrease the amount of air trapped in the material and therefore decrease the stated R-value.