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Advertising supplement provided by
National Gypsum Compan

Continuing Education Use the following learning objectives to focus your study while reading this month’s ARCHITECTURAL RECORD / AIA Continuing Education article. Learning Objective: After reading this article, you will be able to: 1. Learn about the types and fire resistance properties of gypsum wallboard 2. Understand how to navigate through the UL Fire Resistance Directory 3. Analyze several fire-rated gypsum wallboard assembly designs

Gypsum—hydrous calcium sulfate—is an abundant, naturally occurring mineral quarried for a variety of uses, the most common, of course, being gypsum board. Roughly 90 percent of finished interior surfaces are covered today with gypsum products.

Two molecules of water are chemically bound to the calcium crystal during the formation of gypsum. As a result, gypsum is about 21 percent chemically combined water. One of the many unique properties of gypsum is its ability to give up these water molecules as steam when heated, in a process known as calcination, making gypsum board ideally fire-resistant.

When gypsum-protected wood or steel framing members are exposed to fire, the chemically combined water being released as steam acts as a thermal barrier until the slow process of calcination is completed. The temperature directly behind the “plane of calcination” (the heated surface) is only slightly hotter than that of boiling water, significantly lower than the temperature at which steel begins losing its strength, or wood ignites.

This continuing education section will explore the fire-resistant nature of gypsum board, and more specifically, the Underwriters Laboratories (UL) requirements governing its installation.

Underwriters Laboratories Inc. (UL) is an independent, not-for-profit product-safety testing and certification organization that has performed product safety testing on more than 17 billion products. In 2001, UL conducted 537,277 follow-up visits to audit compliance with product certification requirements, ensuring conformity in UL certified brands.

In this section, readers will learn how to navigate Volume 1 of the UL Fire Resistance Directories and create code-compliant designs using an essentially cut-and-paste procedure utilizing the UL directory.

In Volume 3, you will find hourly ratings for dampers, firedoors, glazing materials and related equipment. In Volume 2 you will find hourly ratings for joint systems, through-penetration fire-stop systems, electric circuit protective systems and duct assemblies. Our focus is on Volume 1, which includes hourly rated designs for beams, floors, roofs, columns, walls and partitions.

We will be looking at hourly fire ratings, how they are determined, and what they mean to the designer. This continuing education section will help design professionals understand hourly fire ratings, how they are determined, and how that applies to your designs. We will take readers through a few sample activities to familiarize them with the process of selecting code-appropriate drywall systems.

Richard A. Piccolo, president of a Hoffman Estates, Ill.-based code services company, and Melissa (Missy) Merfeld, product manager for a Charlotte, N.C.-based gypsum manufacturer will be our guides. Piccolo’s firm is a consulting agency specializing in building and fire protection plan reviews, inspections, training and general code consulting services. Piccolo is co-chairman of the Illinois Fire Inspectors Association Codes Standards Committee, and is a past president of the Illinois Council of Code Administrators (ICCA).

The UL Fire Resistance Directory consists of three volumes. The focus today is Vol. 1, with special emphasis on the first 10 pages of the volume—specifically the table on page 1. Understanding this table, entitled “Numbering System For Fire Rated Assemblies”, will allow you to determine which design will be best for your project.

It is important to note here that we will be talking, in all cases, about “assemblies” or “systems” because fire resistance is dependent not only on the gypsum products themselves, but also the framing, insulation and joint compounds that are part of the construction package.

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