The Ontario Building Code | Flashing Installation
220.127.116.11. Flashing installation
(1) Except as provided in Sentence (2), flashing shall be installed at,
(a) every horizontal junction between claddings elements,
(b) every horizontal offset in the cladding, and
(c) every horizontal line where the cladding substrates change and where,
(i) the substrates differ sufficiently for stresses to be concentrated along that line, or
(2) Flashing need not be installed as described in Sentence (1),
(a) where the upper cladding elements overlap the lower cladding elements by not less than 25 mm,
(i) the cladding above and below the joint is installed outboard of a drained and vented air space, and
(ii) the horizontal detail is constructed so as to minimize ingress of precipitation into the air space, or
(c) at horizontal construction joints in stucco, where,
(i) the joint is finished with an expansion-contraction strip, and
(ii) the cladding is installed outboard of a drained and vented air space.
(3) Flashing shall be installed over exterior wall openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings where the vertical distance from the bottom of the eave to the top of the trim is more than one-quarter of the horizontal overhang of the eave.
(4) Flashing described in Sentences (1) and (3) shall,
(a) extend not less that 50 mm upward inboard of the sheathing membrane or sheathing installed in lieu of the sheathing membrane,
(c) terminate at each end with an end-dam,
(i) with a height in millimetres not less than 25 mm or 1/10 of the value of the 1 in 5 driving rain wind pressure in Pa, and
(ii) at the height defined in Subclause (i), extending to the face of the adjacent cladding,
(d) lap not less than 10 mm vertically over the building element below, and
(e) terminate in a drip extending not less than 5 mm outward from the outer face of the buildingelement below.
(5) Where the sills of windows and doors installed in exterior walls are not self-flashing, flashing shall be installed between the underside of the window or door and the wall construction below.