Airtight drywall gaskets are supposed to stop the leakage of air from conditioned spaces to attics, basements and wall cavities. Bill Eich was recently treated to dramatic proof that the gaskets work. When one of the Spirit Lake-Iowa builder's nearly completed homes caught fire one night, the gaskets acted as an effective firestop. The purpose of a firestop is to slow the spread of fire by inhibiting drafts. And that's just what Eich's gaskets did. By stopping air movement, the gaskets managed to keep the fire in one part of the building until the fire department arrived and put it out.