From the Transport Canada Aeronautical Information Manual (available free on line from the TC web site) RAC section para 4.5.2
Figure 4.6—Standard Left-hand Circuit Pattern
NOTES 1: The circuit is normally flown at 1 000 ft AAE.
2: If a right-hand circuit is required in accordance
with CAR 602.96, the opposite of this diagram
is applicable.
(a) Joining the Circuit
(i) Landing and takeoff should be accomplished on or
parallel to the runway most nearly aligned into the
wind. However, the pilot has the final authority and
responsibility for the safe operation of the aircraft
and another runway may be used if it is determined
to be necessary in the interest of safety.
(ii) Unless otherwise specified or required by the
applicable distance from cloud criteria, aircraft
should approach the traffic circuit from the upwind
side. Alternatively, once the pilot has ascertained
without any doubt that there will be no conflict with
other traffic entering the circuit or traffic established
within the circuit, the pilot may also join the circuit
on the downwind leg (Figure 4.6). When joining from
the upwind side, plan the descent to cross the runway
in level flight at 1 000 ft AAE or the published circuit
altitude. Maintain that altitude until further descent is
required for landing.
(iii) If it is necessary for an aircraft to cross the airport
before joining the circuit, it is recommended that the
crossover be accomplished at least 500 ft above the
circuit altitude.
(iv) All descents should be made on the upwind side or
well clear of the circuit