Which gives more insulation value, the Knauf R-38 or the CertainTeed R-19?

The Knauf batt is R-38, double the R-19 of the CertainTeed roll. Use the Knauf where cavity depth allows; the CertainTeed roll suits 2x6 walls at 5.5 in.

Do I need a vapor barrier with the Knauf batt?

Yes, in cold climates. The Knauf is unfaced, so add a separate vapor retarder. The CertainTeed roll has kraft facing that serves that role.

Which is easier to install in a 16 in. on-center wall?

The Knauf batt is 16 in. wide and friction-fits standard stud bays. The CertainTeed roll is 15 in. wide, so you may need to trim or accept a small gap.

How much area does one unit cover?

One Knauf batt covers about 5.3 sq ft. One CertainTeed roll covers 48.96 sq ft, so you need far fewer rolls than batts for the same area.

Is either product GREENGUARD certified?

Both are GREENGUARD certified, so neither has an edge on indoor air quality certification.

Both are fiberglass and last decades when kept dry and covered. The kraft facing on the CertainTeed can tear or degrade faster than unfaced glass, so handle it carefully.

Knauf R-38 Fiberglass Insulation Batt vs CertainTeed R-19 Kraft Faced Insulation Roll

Buy the Knauf R-38 batt for walls, ceilings and attics where you want maximum R-value per inch and no vapor barrier, such as mild climates or over existing kraft paper. Buy the CertainTeed R-19 roll for quick coverage of open framing in a cooler climate, where the kraft facing acts as the vapor retarder. The Knauf batt is a 16 in. x 48 in. piece at R-38; the CertainTeed roll covers 48.96 sq ft at R-19. Compare current prices at each store before you buy, since the two are sold in different formats and quantities.

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