Johns Manville Panel Deck FSK-25 Formaldehyde-free™ thermal and acoustical insulation is available in R-Values up to R-30 and combines fire resistance with an excellent vapor retarder. Panel Deck FSK-25 insulation is offered in precut batts with extra-wide tabs for modular roof deck applications and other specialty commercial applications. This product is designed with a foil facer that can be left exposed where codes permit.