Ruscoe's 12-3 Self-Leveling Sealant is recommended for sealing openings greater than 1/8 inch. It can be used as an effective sealant against water, chemicals, air and dirt for wood or metal doors and windows, metal buildings, mobile home roofs and bodies, truck trailer roofs and bodies, HVAC ducting, concrete, ceramic, brick, metal, stone, masonry, marble and glass. Ruscoe's 12-3 Self-Leveling Sealant is recommended for sealing horizontal seams only.