Question 1

What R-value do I need?

Accepted Answer

R-value requirements depend on climate zone and location in the home. For most US climates: exterior walls need R-13 to R-21, attic floors need R-30 to R-60, and floors over unheated spaces need R-19 to R-30. Check your local building code for specific requirements.

Question 2

What is the difference between batt and blown-in insulation?

Accepted Answer

Batt insulation comes in pre-cut rolls or panels that fit between studs. It is easier to install in new construction. Blown-in insulation is loose fill sprayed into cavities and is better for retrofitting existing walls and attics with irregular framing or obstructions.

Question 3

Can I add insulation on top of existing insulation?

Accepted Answer

Yes, you can layer insulation to increase R-value. Do not compress existing insulation as this reduces its effectiveness. For attics, simply lay new unfaced batts or blow in cellulose on top of the existing layer.

Question 4

Should insulation have a vapor barrier?

Accepted Answer

In cold climates, faced insulation (with kraft paper or foil) should have the vapor barrier facing the warm (interior) side. In hot/humid climates, the barrier faces outward. Never sandwich insulation between two vapor barriers as trapped moisture can cause mold.

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