(1) Except as provided in Sentence (2), chimneys shall be braced in accordance with Subsection 4.3.2. to provide stability under wind loads.
(2) A chimney need not be laterally braced provided,
(a) no horizontal outside dimension is less than 400 mm, and
(b) the chimney extends not more than 3.6 m above a roof or the masonry wall of which it forms a part.