# US 8,739,498 B2 · Fire door > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,498 B2 - Document ID: US8739498B2 - Status: Granted - Kind: B2 - Application number: 13/588,523 - Filed: 2012-08-17 - Published: 2014-02-20 - Granted: 2014-06-03 - Earliest claimed: 2012-08-14 - Assignees: Assa Abloy Door Group, LLC - Applicants: John Wilkinson; Bobby Neal Strickland; Thomas Janicak; Jeffrey Badgett; Mark Drake - Inventors: John Wilkinson; Bobby Neal Strickland; Thomas Janicak; Jeffrey Badgett; Mark Drake - Web page: https://patentgrep.com/patent/US8739498B2 ## CPC - E06B 5/16: Fireproof doors or similar closures; Adaptations of fixed constructions therefor - E06B 3/827: {of metal without an internal frame, e.g. with exterior panels substantially of metal} - E06B 5/161: {Profile members therefor} - E06B 2003/7019: {of corrugated type} - E06B 2003/7036: {of plaster} - E06B 2003/7046: {with provisions for locks, hinges or other fittings} - E06B: FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES (shades or blinds for greenhouses A01G9/22; curtains A47H; lids for car boots or bonnets B62D25/10; skylights E04B7/18; sunshades, awnings E04F10/00) ## Abstract An insulated fire door includes a door shell having spaced first and second exterior panels and a gypsum panel between the first and second exterior panels. The insulated fire door includes a plurality of spacers bonded across an interior side of each of the first and second exterior panels. The spacers maintain the gypsum panel in a spaced position from the interior sides of the first and second exterior panels as the door bows during a fire on one side of the door, until the gypsum disintegrates. Each of the spacers may have a flat portion contacting the gypsum panel, a leg extending from the flat portion spacing the gypsum from the interior sides of the first and second exterior panels, and a flange extending from the leg bonding the spacer to the first and second exterior panels. ## Claims ### Claim 1 An insulated fire door comprising: a door shell having spaced first and second exterior panels, a first vertical door edge and a second vertical door edge opposite the first door edge; a first gypsum panel between the first and second exterior panels; a plurality of first spacers bonded across an interior side of each of the first and second exterior panels, the spacers extending inward from the first and second exterior panels and contacting the first gypsum panel; the spacers maintaining the first gypsum panel in a spaced position from the interior sides of the first and second exterior panels as the door bows during a fire on one side of the door, until the gypsum disintegrates; a lock pocket for receiving a lock, the lock pocket disposed adjacent the second door edge; a second gypsum panel disposed below the lock pocket and a third gypsum panel disposed above the lock pocket; and a stiffener extending vertically within the door between the interior sides of the first and second exterior panels, the stiffener disposed adjacent to the lock pocket away from the second door edge; wherein the first gypsum panel extends horizontally from the first door edge to the stiffener, the second gypsum panel extends horizontally from the stiffener to the second door edge and the third gypsum panel extends horizontally from the stiffener to the second door edge. ### Claim 2 (depends on 1) The door of claim 1 wherein each of the spacers has a flat portion contacting the gypsum panel, a leg extending from the flat portion spacing the gypsum from the interior sides of the first and second exterior panels, and a flange extending from the leg bonding the spacer to the first and second exterior panels. ### Claim 3 (depends on 1) The door of claim 1 wherein the spacers have a length and wherein the length extends vertically within the door. ### Claim 4 (depends on 1) The door of claim 1 wherein the spacers are welded to the first and second exterior panels. ### Claim 5 (depends on 1) The door of claim 1 wherein the stiffener has a leg spacing the interior sides of the first and second exterior panels and flanges extending from the leg bonding the stiffener to at least one of the first and second exterior panels. ### Claim 6 (depends on 1) The door of claim 1 further including a mineral wool insulation extending along a top, bottom and side of the lock pocket between the first and second exterior panels. ### Claim 7 (depends on 1) The door of claim 1 including a lock edge retainer disposed between the stiffener and the lock pocket. ### Claim 8 (depends on 1) The door of claim 1 wherein the door has hinges along a first edge thereof, and further including additional spacers extending vertically between the first and second exterior panels, the additional spacers disposed between the stiffener and the second door edge above and below adjacent the lock pocket. ### Claim 9 (depends on 1) The door of claim 1 including a sheet of ceramic paper extending over the stiffener and overlapping a portion of each of the gypsum panels. ### Claim 10 (depends on 9) The door of claim 9 including a second piece of ceramic paper over the stiffener. ### Claim 11 (depends on 1) The door of claim 1 wherein each of the gypsum panels has a thickness sufficient to permit heat from a fire on one side of the door to flow through the gypsum panel and cause the first and second exterior panels to bow substantially uniformly as a result of thermal expansion thereof, while maintaining sufficient spacer contact with the gypsum panels and having sufficient thermal insulation to meet a fire code, until the gypsum disintegrates. ### Claim 12 (depends on 1) The door of claim 1 wherein the door has a width less than about 32 in. (0.81 m). ### Claim 13 (depends on 12) The door of claim 12 wherein the door has a height greater than about 84 in. (2.13 m). ### Claim 14 (depends on 1) An insulated fire door system having as an active door the door of claim 1 and an inactive door, wherein the active door has hinges along a door edge and the inactive door has hinges along a first inactive door edge and a strike pocket along a second inactive door edge opposite the first inactive door edge, the active and inactive doors meeting at their second edges. ### Claim 15 (depends on 14) The door system of claim 14 wherein the active door has a flexible thermal insulation around the lock pocket between the first and second exterior panels and wherein the inactive door has a strike pocket along the second edge and a flexible thermal insulation along the second edge between the first and second exterior panels. ### Claim 16 (depends on 1) A method of using a fire door comprising: providing the insulated fire door of claim 1, with the plurality of spacers maintaining substantially only air space between the first exterior panel and the gypsum panel and the second exterior panel and the gypsum panel; exposing the door to a heat source on one side of the door; causing the door to bow toward the heat source as a result of thermal expansion of the first and second exterior panels; and using the spacers, maintaining the gypsum panel in a spaced position from the interior sides of the first and second exterior panels as the door bows, until the gypsum disintegrates.