An apparatus for opening and closing a portal in a structure in which a curtain having elongated side portions is placed adjacent opposing sides of the portal. A first end of the curtain is attached to a first end of the portal. An opposite end of the curtain is upturned and attached to a varying means at the first end of the portal to vary the height of a pocket formed in the curtain. Magnetic sealing means are placed on the elongated side portions of the curtain and on the opposing sides of the portal. The portal is closed as the varying means lowers the height of the pocket, wherein the magnetic sealing means on the curtain engage the magnetic sealing means on the opposing sides of the portal, thereby sealing the portal. The portal is opened as the varying means raises the height of the pocket, wherein the magnetic sealing means on the curtain disengage the magnetic sealing means on the opposing sides of the portal, thereby unsealing the portal.