Floors and roofs on mass timber buildings are constructed from large panels of engineered wood, such as cross-laminated timber (CLT) or mass plywood. Designers join these prefabricated panels together on site to create a structural horizontal diaphragm to transfer wind and seismic loads to the vertical elements of the lateral force resisting system. Shear forces between panels must be transferred through these panel-to-panel connections. Conventional wood structural panel sheathed diaphragms have shear capacities and fastener spacing tabulated in Special Design Provisions for Wind and Seismic (AWC SDPWS). Mass timber diaphragms, on the other hand, require some more design work by the designer.