The Maiman Company has introduced a number of positive pressure fire-rated wood doors in the past few years. We are also testing and designing more product lines to qualify for this rating. For example, we now offer Thermal Fused flush wood doors in 20-90 minute fire ratings.

Positive pressure doors come in two varieties. Both make use of intumescent seals. An intumescent material is one that expands when heated; in fire testing, this material seals the gaps around a door and prevents super-heated gases from escaping.

A Category A door has intumescent seals built into the structure of the door. These doors will have a different structural profile and will protect against fire; an additional gasket kit is available to defend against smoke.

A Category B door is a neutral pressure door with an additional smoke/fire gasket kit to provide the intumescent seals. We provide those kits along with installation instructions; actual installation is the client's responsibility.

Reference Articles

• A general introduction on positive pressure
• A guide on identifying references to positive pressure (Comprises part of WDMA Technical Bulletin)
• Some information on categories, smoke ratings, and other topics (Also comprises part of WDMA Technical Bulletin)
• A Maiman Memorandum on positive pressure (11/01/2000)
• Updated Maiman Memorandum on positive pressure (4/27/2001)
• Additional information on doors that have passed positive pressure testing