How high can a fence be 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.

• Maximum height: 1.2 m in the front yard (1.8 m over 2.75 m from the façade); 1.8 m in the side and rear yards. (ch. 7, div. 8, subdiv. 3, "Height of a fence, wall or low wall and hedge")
• Never on a public street right-of-way. (ch. 7, div. 8, subdiv. 3, "Public street right-of-way")
• Allowed materials: enamelled steel, wrought iron, galvanized or vinyl chain-link, painted or stained treated wood, PVC; masonry low wall. Prohibited: barbed wire, chicken wire, sheet metal. (ch. 7, div. 8, subdiv. 3, "Allowed materials" and "Prohibited materials")
• A fence is mandatory around an in-ground or above-ground pool. (ch. 7, div. 8, subdiv. 3, "Obligation to install a fence", 2°)
• A certificate of authorization is required to put up a fence, a retaining wall or a low wall. (City page on permit and certificate applications)

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