The "one in three" rule applies to unsuppored load bearing joists, i.e. the hole diameter opening in the joist to allow pass-through cannot exceed one-third of the depth of the joist. E.g. a hole diameter through a 2" X 9" joist cannot be larger than 3". My question concerns a joist at the very edge of a basement cinder block wall that rests on a sole plate which lays flat on the cinder blocks. Will the rule apply here as well? If a six inch hole is drilled through the joist, does it offer enough support because it is resting on the sole plate which is in direct contact with the cinder blocks?