Properly Use Caulks and Sealants

In the construction of exterior wall and roof coverings, there will be joints and seams that require or benefit from the appropriate specification, use, and maintenance of caulks or sealants. When possible, use flashing instead of caulking and use caulking only as a supplement to flashing that is properly integrated with the WRB installation (refer to Section 4.2.7 and 4.2.8). Whether caulking is used to cover up poor detailing or required as a necessary component in certain details, it can have a significant impact from a durability and liability standpoint.

In the absence of guidelines for a specific application, the generic caulk recommendations in Table 4–9 should be considered and the selected caulk manufacturer’s instructions carefully followed. Poor performing caulks or poorly installed caulking can fail in less than a year, creating an unreasonable expectation for maintenance and greater likelihood of moisture problems (see text box). A high quality caulk installation requires skill and appropriate ambient temperature, dry and clean surfaces, and an adequate joint gap to allow the caulk to act elastically without pulling loose. Too thick of a bead restricts the flexibility of the caulk, which can result in failure of the joint. Instead, the use of backer rod really matters and can result in a better formed, more flexible bead that will adhere far better. For additional guidance, refer to appropriate resources in Section 4.4, such as ASTM C1193.