Seal openings in fire-resistant floors and walls to stop the spread of smoke and flames. Often used to fill gaps around pipes or conduit, this cement forms a rigid, tight-fitting shield. It’s heavier and messier to apply than fire-stop blocks or sheets, but it's an economical choice for covering a large area. You can also paint over this cement once it dries.

This cement comes as a powder—mix in water until you reach the consistency you need. The thicker the cement, the better it will stick to walls; thinner cement dries with a smoother finish on floors.

Cement in a pail is best for small, infrequent jobs. The pail is resealable and has a carrying handle.