Attic Insulation Calculator

The key to insulation performance is The R-Value. R-value measures a material's resistance to heat flow; the higher the number, the better the insulating power. However, R-value is only half the story. Air Sealing is equally critical. Before you add more insulation, you must seal the "bypass" points—where wires, pipes, and light fixtures penetrate the attic floor. Without proper air sealing, your new insulation will act like a filter for escaping air rather than a barrier to heat. Our calculator helps you estimate the material, but we highly recommend using expanding spray foam to seal these gaps before the insulation is installed. This "Seal and Insulate" approach is the only way to achieve true energy efficiency.

Another vital consideration is Attic Ventilation and Eave Baffles. Insulation should never block the flow of air from your soffit vents to the ridge vent. If you cover these vents, moisture will build up in the attic, leading to mold and wood rot. Professionals install "Baffles" (foam or plastic channels) at the eaves to keep the insulation away from the vents. Our tool provides the volume for the floor, but your shopping list should include enough baffles for every rafter bay. Finally, focus on Material Density. Blown-in insulation will naturally "settle" over the first 12-24 months. Professionals always "over-blow" by about 10-15% to ensure that the settled height still meets the target R-value. Our calculator factors in this settling to ensure your home remains efficient for decades to come.