The Association’s technical staff is available for consultation on specific issues relating to the specification or use of gypsum board. Most of the technical questions that arise are answered in one of the Gypsum Association publications; many specific gypsum and construction issues are addressed by one of the Association’s topical papers, and a large number of code and compliance matters are covered by one of the Evaluation Reports or code acceptances published by local, state, or model code bodies. Regardless of the published information available, there may be times when it is necessary to speak with or contact an expert on the subject.
Great numbers of questions regarding interpretations of Gypsum Association publications have been addressed by our technical experts. Issues and concerns that seem unique to a specific project often need the advice of someone specializing in gypsum board technology. However, what seems unique to a given project, may not be so unique. So, before you contact the technical department for help and advice, you might benefit from checking out the answers to Frequently Asked Questions (FAQs) below. FAQs are updated periodically, especially as seemingly unique questions recur.
Feel free to contact the Association staff by fax, phone, mail, or E-mail; we welcome the opportunity to assist you.
- The name of the manufacturing company or a unique alpha code identifying the name of the manufacturing company. The decision to print the name of the company or to create and use a unique code is at the discretion of the company.
- A code identifying the manufacturing facility and, where applicable in a multi‐line facility, the production line.
- A code identifying the date and time of manufacture.
- The country of manufacture as designated by the three letter code in ISO 3166‐1. The code for United States is USA. The code for Canada is CAN.
However, fires also bring with them two additional elements, smoke and water. Water is the easiest to assess. First, it is critical to determine if the studs and other materials in the wall cavity are dry and undamaged. To do this, it is likely that the at least some of the gypsum wall board will be removed to inspect the cavity and its contents, thus, requiring some replacement. If it can be verified that the contents of the wall cavity are dry and undamaged without removal of existing gypsum wall board, a thorough examination of the wall board is required; it must be dry and free of mold with the paper facing completely intact. If any of these are in doubt, it is best to play it safe and replace the board. Smoke is more difficult to assess as it is very subjective. Some individuals claim to smell the smoke in sealed and repainted rooms years after a fire. Some people never catch a hint of the smell. Restoration services exist that are licensed and bonded, and these should be consulted with/by the property owner/resident as to whether a restoration without replacement is possible.
All gypsum wallboard used in interior wall and ceiling applications should be finished with tape and joint compound embedded in joints and interior angles, as well as an appropriate primer and paint. The application of these materials protects the integrity of gypsum wallboard. Note, in a fire-rated system that includes multiple layers of wallboard, only the final, visible, wallboard surface needs to be finished with tape, joint compound, primer and paint.
Exceptions can be made in areas that are concealed and received little or no active use, examples include attics and plenum areas above ceilings and attics. In these areas, tape and joint compound are required to provide fire resistance.
To determine the level of finish appropriate to a specific situation, including gypsum panel products used as a substrate for tile, as a base for textured finishes, wallcoverings, and paints of various sheens, and lighter and darker tones, consult GA-214-2015, Recommended Levels of Finish for Gypsum Board, Glass Mat and Fiber Reinforced Board, available in the GA Bookstore.
Want to learn more? Read Thermal Barriers and Ignition Barriers for the Spray Polyurethane Foam Industry.
More information on joint tolerance is contained in the Northwest Wall and Ceiling Bureau Document #500-103 Gaps at Gypsum Board Joints available here.
715.1 General. Joints installed in or between fire-resistance rated walls, floor or floor/ceiling assemblies and roofs or roof/ceiling assemblies shall be protected by an approved fire-resistant joint system designed to resist the passage of fire for a time period not less than the required fire-resistance rating of the wall, floor or roof in or between which the system is installed. Fire-resistant joint systems shall be tested in accordance with Section 715.3.
Exception: Fire-resistant joint systems shall not be required for joints in all of the following locations:
- Floors within a single dwelling unit.
- Floors where the joint is protected by a shaft enclosure in accordance with Section 713.
- Floors within atriums where the space adjacent to the atrium is included in the volume of the atrium for smoke control purposes.
- Floors within malls.
- Floors and ramps within open and enclosed parking garages or structures constructed in accordance with Sections 406.5 and 406.6, respectively.
- Mezzanine floors.
- Walls that are permitted to have unprotected openings.
- Roofs where openings are permitted.
- Control joints not exceeding a maximum width of 0.625 inch (15.9 mm) and tested in accordance with ASTM E 119 or UL 263.
Additional information on the topic of firestopping can be obtained from a firestopping manufacturer or The International Firestop Council www.firestop.org/.
The GA does not list R-values for wall assemblies due to the high degree of variability between what is shown in GA-600 and what is actually constructed. Common elements, such as resilient channels, thicker studs, decreased stud or joist spacing, varying amounts and types of insulation, etc., are variables that are allowed for any system, per the General Explanatory Notes in GA-600. Variables such as cladding type also play a role in total R-value.
However, calculating the R-value for an assembly is not exceptionally difficult, as it is essentially the sum of the R-value of the individual layers, accounting for stud closeness. ASHRAE, ICC, DOE and others have developed practices and methods for calculating R-value that are code acceptable. One online tool based on ASHRAE’s Handbook of Fundamentals information and practice is available at www.ekotrope.com/r-value-calculator/. A quick online search will provide additional online tools for performing these calculations.
The Gypsum Association publishes and revises numerous technical documents each year. Occasionally, the Association must issue an errata. The following errata is associated with section GA-216-2016, Application and Finishing of Gypsum Panel Products. On page 3, section 184.108.40.206 should read:
220.127.116.11 Where studs complying with ASTM C645 are used to receive Abuse Resistant or Impact Resistant Gypsum panels, they shall be not less than 0.0312 in. (0.792 mm) design thickness and shall be in accordance with sections 4.3 and 8.1 of Specification C645.
The correction clarifies the recommended thickness for steel studs receiving abuse resistant or impact resistant gypsum panels contained in GA-216-2016. The GA is communicating this errata as widely as possible. The electronic version of GA-216-2016 will reflect this change and hardcopies of Application and Finishing of Gypsum Panel Products are now issued with the clarification noted as an errata inserted on a separate sheet. Download a PDF copy of this errata for your records.