Can you add a basement apartment in Dorval?

The rules, in short

Rules from Chapter 7 (Residential neighbourhood zones H) of By-law RCM-60A-2015. The consolidation does not print section numbers, so sections are cited by their heading, except sections 336 and 356, which the text names. Setbacks come from each zone's grid of uses and standards.

• Intergenerational unit: only in a detached single-family house, one only, for members of the owner's or occupant's family; subject to the by-law on conditional uses. (ch. 7, s. 336, 4°, a) to e))
• It must stay permanently connected to the main dwelling; one additional parking space; no separate civic number; a single electrical meter. (ch. 7, s. 336, 4°, f) to i))
• A dwelling must be entirely above ground: no dwelling unit in a cellar or basement. (ch. 7, div. 1, "Dwelling in a basement or cellar")
• An accessory building cannot contain a dwelling unit. (ch. 7, div. 1, "Additional uses, structures, equipment and accessory uses", 3°)

Summary by Radar Foncier, in our own words: the official French text of the by-law, linked above, prevails.

Applying in Dorval

• Processing time: 30 working days after a complete application is filed
• Urban planning department: 514 633-4084
• Permits on the municipality's website