A pool enclosure is a safety system, not an ordinary boundary fence
Municipal pool rules can control enclosure height, gate hardware, openings, climbability, distance from the water and whether the enclosure must be inspected before the pool is used. A backyard fence that is perfectly acceptable as a property-line fence may still fail the pool-enclosure standard.
Permit and inspection requirements vary by city
Toronto currently requires a pool fence enclosure permit and an approved zoning certificate for a swimming-pool enclosure. Its rules also address gate operation, openings, climbability and minimum enclosure heights. Ottawa requires a pool enclosure permit and inspection, and its current rules require an enclosure at least 1.5 m high for covered pools subject to the by-law.
See the City of Toronto fence and pool-enclosure guidance and the City of Ottawa pool-enclosure guidance.
Hot tubs can be treated differently
Some municipalities or building-code regimes allow an approved lockable safety cover to change the enclosure requirement for a hot tub; others still require additional conditions. Do not assume a hot tub follows the ordinary fence rule or the same rule as an in-ground pool.
Existing fences may need upgrading
Buying a pool does not automatically make an existing yard fence compliant. Gates, horizontal members, nearby climbable objects, gaps beneath the fence and access from the house can all matter. The enclosure should be checked against the current pool rule before water is added.
Check the pool rule separately
When a city publishes both a general fence bylaw and a pool-enclosure bylaw, use both. The pool rule can be more restrictive and may override the ordinary fence standard for the enclosure.