Abstract: A mold for retaining a sealing material within a passageway of a building partition. The mold consists of an annular ring member integrally coaxially connected to one end of a cylindrical sleeve member. The annular ring member is of greater transverse dimension than said sleeve member. Said mold may be constructed to appear as an inverted top hat. The cylindrical sleeve member may be provided with a longitudinal slit means for opening up said sleeve member and connecting it to a building tubular member such as a pipe to fit as a jacket thereon. In use the sleeve member is connected onto a building tubular member and may be fastened thereon, and the planar surface of said annular ring member is associated in facial planar relation with a building partition. Thereafter sealing material is placed in the area between said tubular member and said aperture wherein the planar surface of said annular ring member acts as a dam until setting of the sealant occurs.