7.5.1.1.

(1) Except as provided in Sentences (3) and (4), every trap shall be protected by a vent pipe.

(2) Drainage systems shall be protected by the installation of a system as provided in Subsections 7.5.4. and 7.5.5. by the installation of,

(a) additional circuit vents,

(b) branch vents,

(c) circuit vents,

(d) continuous vents,

(e) dual vents,

(f) fresh air inlets,

(g) headers,

(h) individual vents,

(i) offset relief vents,

(j) relief vents,

(k) stack vents,

(l) vent stacks,

(m) wet vents, or

(n) yoke vents.

(3) A trap that serves a floor drain or hub drain need not be protected by a vent pipe separately where,

(a) the size of the trap is not less than 3 in.,

(b) the length of the fixture drain is not less than 450 mm,

(c) the fall on the fixture drain does not exceed its size, and

(d) the trap is connected to a horizontal drainage pipe that terminates at its upstream end in a 3 in. stack.

(4) A trap need not be protected by a vent pipe,

(a) where it serves,

(i) a subsoil drainage pipe, or

(ii) a storm drainage system, or

(b) where it forms part of an indirect drainage system.