Guardian Knauf R19 Unfaced Fiberglass Roll vs CertainTeed R-19 Kraft Faced Insulation Roll

Both rolls cover 48.96 sq ft at R-19, so the real choice is the facing. The CertainTeed kraft-faced roll has a vapor retarder built in, which suits exterior walls and ceilings in most climates and saves a separate sheet. The Knauf roll is unfaced, so it goes where you want vapor to pass or where a separate barrier is already in place. Reviewers of both brands report clean cutting and good recovery; the Knauf roll is thicker at 6.25 in versus 5.5 in, which can matter in tight cavities.

• Choose the Knauf roll if you are insulating an attic floor, adding over existing insulation, or need vapor to pass through and will handle the barrier separately.
• Choose the CertainTeed roll if you are insulating exterior walls or ceilings and want the kraft vapor retarder built into the product.