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September - October 2002

WDMA OPENS UP
ALAN CAMPBELL

Turning Up the Heat
Positive-Pressure Tests as a Standard 
by Alan J. Campbell

Quality products that perform are always the goal. Doors are a system of materials that must meet certain established criteria in order to perform properly for the application. In todayís world, it takes a variety of materials to make a door, including vinyl, wood, composites and others. 

Performance Standards
No matter the material, any door or window product should be rated according to its performance in the field. What it is made of really doesnít matter. What matters is if the product can meet required testing and performance standards. 

Wood doors are increasingly viable products for fire-rated applications and this industry will continue to meet and exceed expectations as a growing market segment. Wood doors are beautiful products that can, when designed properly, meet even grueling applications that require fire ratings of 20, 45, 60 or even 90 minutes. 

According to the 2002 ďStudy of the U.S. Market for Windows, Doors and Skylights,Ē commissioned by the Window and Door Manufacturers Association (WDMA) and the American Architectural Manufacturers Association, and conducted by Ducker Research Co. Inc. in Bloomfield Hills, Mich., fire-rated wood-flush doors continue to find industry acceptance. Fire-rated wood-flush doors accounted for approximately 1.48 million units sold in 2001, and 20-minute-rated products represent more than two-thirds of all those types of doors. 

Positive Pressure Is Here
An ongoing issue with regards to fire-rated doors is the idea of positive-pressure testing versus neutral methods. By no means is this a new debate; in fact, itís an issue thatís been in discussion for years. 

Hereís what it is. During fire tests, pressures develop in a furnace. Positive pressure forces air out of the furnace. Traditionally, with so-called neutral pressure testing, negative pressure sucks air into the furnace. Experts argue that this cooler outside air lowers the temperature inside the furnace in areas where the air is coming through cracks and openings. It also can cause faster burning due to an increase in the supply of 
oxygen. 

During positive-pressure testing, the test method requires that a neutral pressure plane be established to create a positive pressure at the top of door or window assemblies undergoing the test. The result is to minimize the impact of potential negative pressure points to limit the pressure 
differences. 

Itís a technical and scientific debate, but positive-pressure testing of doors appears destined to become a standard method required by building-code bodies. In 1997, the International Council of Building Officials approved a change to the Uniform Building Code that requires fire doors to be tested under positive pressure instead of neutral pressure. Most recently, many code groups across the United States have adopted the International Building Code, which also contains the requirement for positive pressure. Many states already require positive-pressure-rated fire doors. By 2003, many states will have adopted positive-pressure requirements.

While there is still debate concerning positive-versus-neutral pressure testing, WDMA wants to help sort out whatís going on with this issue. To further clarify this test method, we have posted a technical bulletin on positive pressure doors at www.wdma.com

Some items still have to be worked out. Specifiers and builders wonder how they will be able to tell when door products meet the new codes. Manufacturers want to know specifically how and by when they must comply. 

WDMA has been anticipating the change and has included references in its soon-to-be-released revised I.S. 1-A Architectural Flush Door Standard. This will assure that positive pressure is included in the standard that manufacturers use in the production of doors and help them meet appropriate requirements according to the fire rating.

Wood doors are beautiful products that can meet the needs of many different, even demanding, environments. Fire-rated doors are built to stand up to the test. 



Alan J. Campbell, CAE, serves as president of the WDMA, based in Des Plaines, Ill.

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