The Ontario Building Code | Lath and Reinforcing

9.28.1.2. Lath and Reinforcing

(1) stucco lath or reinforcing shall be used to attach stucco to any substrate other than masonry.

(2) stucco lath or reinforcing shall be used to attach stucco to masonry where,

(a) the masonry is soft-burned tile or brick of less strength than the stucco, or

(b) the masonry surface is not sound, clean and sufficiently rough to provide a good key.

(3) stucco applied over masonry chimneys shall be reinforced.