Diminished Housed Tenon??? Please, call this something else, if anything it is the opposite, increased yes, tenon no (full section), housed no (no level bearing) and a slip through notch (not a fixing joint)


In the normal sense, diminished haunch, tusk tenons and soffit tenons have first lower down a lengthened penetration to provide a strong level bearing, second the diminishing length provides re-enforcement of the bearing while decreasing the cutting away of the receiving timber. This is especially important in maintaining bearing capacity in the beam that is notched to carry the joists.

One other thing, normally joists are tying members, if your joist fails to tie a frame then your joist is failing at a primary task.