The Ontario Building Code | Attachment of Studs to Runners
220.127.116.11. Attachment of studs to Runners
(1) studs shall be attached to runners by screws, crimping or welding around wall openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings, and elsewhere where necessary to keep the studs in alignment during construction.
(2) Where clearance for expansion is required in Article 18.104.22.168., attachment required in Sentence (1) shall be applied between studs and bottom runners only.