Johns Manville Formaldehyde-Free™ Fiberglass Insulation (Specific for 2" by 8" STEEL framed walls with joists spaced 24" apart) R-Value: 28 Dimensions: 8½" x 24" Coverage: 64.0 sq. ft./bag Application: Attics JM Formaldehyde-Free™ fiberglass insulation promotes better indoor air quality, provides superior thermal efficiency and a reduction in sound. Data Sheet