Disclosed is a magnetically mountable seal, and method of use thereof. The seal is capable of sealing a gap between a door, and either its frame or a second door. The magnetically mountable seal comprises a magnetic portion, magnetically attached to a surface; and a seal portion secured to the magnetic portion. The method of use comprises the steps of: (a) magnetically attaching the magnetic portion to one of the first door, its frame, and the second door; and (b) securing the sealing portion so that the sealing portion covers the gap when the first door is in a closed position and does not interfere with the functionality of the first door when the first door is in an open position. Improved energy efficiency around the gap reduces energy consumption. The sealing portion can be a thermal barrier, acoustic barrier, hermetic, odor barrier, contagion barrier, and fire barrier.