Roof cement is a type of roofing material that is used to seal cracks, gaps, and holes in roofing materials. It is a thick, tar-like substance that is applied with a brush or trowel, and it dries to a hard, waterproof finish. Roof cement is typically used on asphalt shingle roofs, but it can also be used on metal roofs, clay tile roofs, and concrete tile roofs. It is critical to apply roof cement correctly in order to achieve the best results.