The Ontario Building Code | Ducts

9.32.3.10. Ducts

(1) ventilation ducts shall conform to the requirements of Part 6 for supply ducts, except that exhaust ducts that serve only a bathroom or water closet room may be of combustiblematerial provided the duct is reasonably airtight and constructed of a material impervious to water.

(2) Exhaust ducts shall not discharge into heated or unheated enclosed spaces.

(3) Where an exhaust duct passes through or is adjacent to unheated space, the duct shall be insulated to not less than RSI 0.5.

(4) Where a duct carrying outdoorref ="http://thehandyforce.com/doors/" title ="Toronto Door installer">door air that is not tempered or not mixed with indoor air passes through heated space, it shall be insulated to not less than RSI 0.5 except that, where such a duct is exposed in the heated space for more than 3 m of length in the heated space, it shall be,

(a) insulated to not less than the values listed in Table 9.32.3.10.A., and

(b) provided with a vapour barrier.

Table 9.32.3.10.A.
insulationhttp://thehandyforce.com/insulation/" title ="Toronto home insulation">insulation of Ducts Carrying outdoorref ="http://thehandyforce.com/doors/" title ="Toronto Door installer">door Air

Forming Part of Sentence 9.32.3.10.(4)

Item	Column 1 Outside Winter design Temperature as per MMAH Supplementary Standard SB-1, "Climatic and Seismic Data"(1), °C	Column 2 Minimum Thermal Resistance, RSI
1.	–7 to –11	0.5
2.	–12 to –17	0.9
3.	–18 to –24	1.2
4.	–25 to –29	1.4
5.	–30 to –34	1.8
6.	–35 and colder	2.1

Notes to Table 9.32.3.10.A.:

⁽¹⁾ The outside winter design temperatures shall be those listed for the January 2.5 percent values.

(5) A kitchen exhaust duct not equipped with a filter at the inlet end shall be designed and installed so that the entire duct can be cleaned.

(6) Ductwork for cooking appliance exhaust fans shall,

(a) be of noncombustible, corrosion-resistant material, and

(b) lead directly to the outdoorref ="http://thehandyforce.com/doors/" title ="Toronto Door installer">doors without connection to other exhaust fans or ducts.

(7) Ductwork for cooking appliance exhaust fans shall be equipped with a grease filter at the intake.

(8) All ductwork shall be permanently supported or clipped to prevent sagging, excessive movement and vibration.

(9) All ducting connected to supply and exhaust fans shall be constructed so as to inhibit air leakage at joints.

(10) Where rectangular duct is used in place of round duct, it shall be selected according to Table 9.32.3.10.B.

Table 9.32.3.10.B.
Equivalent Duct Sizes

Forming Part of Sentence 9.32.3.10.(10)

Item	Column 1	Column 2	Column 3	Column 4	Column 5
	Required Round Duct Size, mm	Permitted Equivalent Rectangular Duct Size, mm
		Stack Duct	100 mm Depth	125 mm Depth	150 mm Depth
1.	75	82 × 250	57 × 100
2.	100	82 × 250	89 × 100	75 × 125	75 × 150
3.	125	82 × 250	125 × 100	100 × 125	89 × 150
4.	150	82 × 300	200 × 100	150 × 125	125 × 150
5.	175	82 × 350	275 × 100	200 × 125	175 × 150
6.	More than 175	Part 6 design	Part 6 design	Part 6 design	Part 6 design