There are two primary fire test methods that are used to establish the fire ratings of doors. The first is UL 10B and is referred to as neutral pressure; the second is UL 10C, and is referred to as positive pressure. The difference between the two test methods concerns the location of a neutral pressure plane in the test furnace. In the late 1990’s, the test method required in building codes changed to a positive pressure test method. This change was adopted in the Uniform Building Code (UBC) and the International Building Code (IBC) for swinging-type fire doors. Fire doors required to be tested to either method may be specified by calling out the test method or by indicating that the product must meet a specific section of a model building code.