The Ontario Building Code | Support of Walls
(1) Non-loadbearing walls parallel to the floor joists shall be supported by joists beneath the wall or on blocking between the joists.
(2) Blocking referred to in Sentence (1) for the support of non-loadbearing walls shall be not less than 38 mm by 89 mm lumber, spaced not more than 1.2 m apart.
(3) Non-loadbearing interior walls at right angles to the floor joists are not restricted as to location.
(4) Loadbearing interior walls parallel to floor joists shall be supported by beams or walls of sufficient strength to transfer safely the design loads to vertical supports.
(5) loadbearing interior walls at right angles to floor joists shall be located not more than 900 mm from the joist support when the wall does not support a floor, and not more than 600 mm from the joist support when the wall supports one or more floors, unless the joist size is designed to support such loads.