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Baby, It’s Cold Outside—and Inside

Not that you need reminding, but cold weather is here at least for most of the country. With cold weather comes the need to ensure the work space is properly conditioned environmentally. The requirements for conditioning the building are well known and well documented; most manufacturers clearly state these requirements in their product literature.

The strongest document available is ASTM C840, Standard Specification for Application and Finishing of Gypsum Board. Not only is this a consensus standard, it is also referenced by both the International Building Code and the International Residential Code.

The language from C840 is as follows:

4. Environmental Conditions

4.1 Application of Gypsum Board, Joint Treatment Materials, and Adhesives—Room temperature shall be maintained at not less than 40°F (4°C) during application of gypsum board except when adhesive is used for the attachment of gypsum board. For the bonding of adhesive, joint treatment, texturing, and decoration, the room temperature shall be maintained at not less than 50°F (10°C) for 48 h prior to application and continuously thereafter until completely dry.

4.1.1 When a temporary heat source is used, the temperature shall not exceed 95°F (35°C) in any given room or area.

4.1.2 Adequate ventilation shall be maintained in the working area during installation and curing period.

4.2 Gypsum board shall be protected from direct exposure to rain, snow, sunlight, or other excessive weather conditions.

NOTE 1—Where manufacturers’ recommendations differ from the above, follow their recommendations.

4.3 Ready-mixed joint compounds shall be protected from freezing, exposure to extreme heat and direct sunlight.

Pretty clear instructions, right? Unfortunately, I know many of you have had problems with getting the GC or owner to pay for the bills necessary to make this happen. When they do not make it happen you end up in trouble with callbacks to correct problems that never would have occurred if the environmental conditions had been maintained as specified by C840.

So you have a problem when the GC or owner does not want to spend the money to provide the services needed or start up the HVAC system for the building. If it is a repeat GC or owner, you may not have a big problem if you provide them with the requirements contained in C840 as a reminder of what is needed for you to do your job and provide an acceptable finished product. If it is new GC or owner, you might have to become an educator and convince him that it is in their best interest in the long run to spend the money up front rather spend it in long-term finger-pointing.

Update: Control Joints in Gypsum Sheathing

On another subject I wrote about several months ago, I have some news about control joints in gypsum sheathing. In Atlanta during ASTM Committee Week in mid-November, there was a meeting of the task group on control joints in gypsum sheathing, and the information that came out of it was interesting, to say the least.

As task group chairman I posed several questions to the producer members of C11.03 Specifications for the Application of Gypsum and Other Products in Assemblies. The first question was, “What is the definition of a control joint? Answer: a joint to relieve stress across a surface, in this case, gypsum sheathing. The next question was, “Does this joint have to be covered with a metal device to close the joint?” The answer is no. Because the joint does not have to go through the finish cladding, it does not always need to be covered.

So when does it need to be covered? When a trowelled on weather resistive barrier is applied on the gypsum sheathing. The covering only needs to be tape, not a metal device. There have been cases where cracks have occurred in the WRB when it was applied over gypsum sheathing with open joints.

Another important question was this one: “Does the control joint have to continue through the finished cladding?” No, it does not. The only time it does is when it coincides with a control joint in the finished cladding or at a building expansion joint.

Going forward, my effort will be to prepare a ballot to clarify the requirements for control joints in gypsum sheathing. The language as it exists is not clear. Quite frankly, when I first read the requirements for control joints I thought of the metal devices used in stucco, so I can understand why an inspector would make the interpretation that a metal device is required and the sheathing control joint has to penetrate the finished cladding. The producer members of C11.03 are now very aware of the potential problems that can occur with the current wording.

Donald E. Smith, CCS, is AWCI’s director of technical services. Send your questions to, or call him directly at (703) 538.1611.

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