Published On 5/12/2023
As a requirement of the building codes, Simpson Strong-Tie® joist and truss hangers are tested in accordance with approved
standards which define how to construct the test setup, how to load the assembly, and how to interpret the results. The test
standards and Acceptance Criteria for these hangers, ASTM D7147 and ICC-ES AC13, require that they be tested with a 1⁄8"
gap between the end of the carried member and the carrying member. Therefore, for hangers to achieve the full published
allowable loads, the same conditions must be met in the field, i.e., that gaps between the carried member and carrying
member not exceed 1⁄8".
Testing performed by Simpson Strong-Tie has indicated that joist and truss hanger allowable loads are decreased when larger
gaps are present. The amount of decrease in allowable load depends on the size of the gap, the type of hanger used and the
type and location of fasteners. Figures 1 and 2 below illustrate two ways in which gaps affect performance.