CRA indicates that a capital loss can be recognized on duplex land that is used personally less than 50%

At civil (and common) law, land and building are a single property (although this rule is overridden for CCA/recapture purposes). Consequently, if a duplex property is used more than 50% for rental use, so that it is not personal-use property, a capital loss realized on a sale of the property and relating to all of the non-depreciable component can be recognized (subject to s. 13(21.1)) as a capital loss notwithstanding its partial personal use.

Neal Armstrong. Summaries of 7 October 2016 APFF Financial Strategies and Instruments Roundtable, carryforward of 2013 APFF Roundtable, Q.2 under s. 54 – personal-us property and Reg. 1102(2).