
EXTERIOR HORIZONTAL VENT TERMINATION CLEARANCE REQUIREMENTS
*See Item D in the Text Below.
  | Exterior Wall  | Center Line  | 
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  | of Termination  | 
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  | *18”  | 
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  | Horizontal  | V  | 
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  | Termination  | 
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  | 18”  | Ventilated Soffit  | 
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  | Inside Corner  | 
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  | Detail D  | 
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L  | 
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  | Fixed  | 
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  | Closed  | 
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  | F  | V  | Window  | 
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  | X = Air Supply Inlet  | V  | |
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  | NOTE: Local Codes Or Regulations  | 
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  | May Require Different Clearances.  | 
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  | NOTE: Location Of The Vent Termination  | 
Corner Detail  | 
  | Must Not Interfere With Access To The  | |
  | Electrical Service.  | ||
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A  | 
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  | A  | = 9” in U.S.  | |
  | = 12” in Canada  | ||
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  | H  | 
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  | 3 ft.  | 
B  | 
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V  | Operable  | 
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  | Window  | 
  | 3 ft.  | 
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B  | 
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B  | B  | 
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I
= Vent Termination 
 = Area where Termination is not Permitted
N ![]()
 P 
 N
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V
Q
D
V
M
V
  | Canadian Installation* | US Installation** | 
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A = Clearance above grade, veranda, porch, deck, or balcony.  | 12 inches (30cm)* | 12 inches (30cm)**  | 
B = Clearance to window or door that may be opened.  | 6 inches (15cm) for appliances | 6 inches (15cm) for appliances  | 
  | < 10,000 Btuh (3kW), 12 inches (30cm)  | < 10,000 Btuh (3kW), 9 inches (23cm)  | 
  | for appliances > 10,000 Btuh (3kW) | for appliances > 10,000 Btuh (3kW) and  | 
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  | < 50,000 Btuh (15kW), 12 inches (30cm)  | 
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  | for appliances > 50,000 Btuh (15kW)**  | 
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C = Clearance to permanently closed window | 12 inches (305mm) recommended to  | 9 inches (229mm) recommended to  | 
  | prevent window condensation | prevent window condensation  | 
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D = Vertical clearance to ventilated soffit located above the  | 18 inches (458mm) | 18 inches (458mm)  | 
termination within a horizontal distance of 18 inches (458mm)  | 
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from the center line of the termination  | 
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E = Clearance to unventilated soffit***  | 12 inches (305mm)  | 12 inches (305mm)  | 
F = Clearance to outside corner  | 5 inches (12.7cm) minimum  | 5 inches (12.7cm) minimum  | 
G = Clearance to inside corner  | 6 inches (15.2cm) minimum  | 6 inches (15.2cm) minimum  | 
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H = Clearance to each inside of center line extended above  | 3 feet (91cm) within a height of 15 feet  | 3 feet (91cm) within a height of 15 feet  | 
meter/regulator assembly | above the meter/regulator assembly*  | above the meter/regulator assembly**  | 
I = Clearance to service regulator vent outlet | 3 feet (91cm)* | 3 feet (91cm)**  | 
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J = Clearance to nonmechanical air supply inlet to building or  | 6 inches (15cm) for appliances  | 6 inches (15cm) for appliances  | 
the combustion air inlet to any other appliance  | < 10,000 Btuh (3kW), 12 inches (30cm)  | < 10,000 Btuh (3kW), 9 inches (23cm)  | 
  | for appliances > 10,000 Btuh (3kW)  | for appliances > 10,000 Btuh (3kW) and  | 
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  | < 50,000 Btuh (15kW), 12 inches (30cm)  | 
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  | for appliances > 50,000 Btuh (15kW)**  | 
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K = Clearance to a mechanical air supply inlet | 6 feet (1.83m)* | 3 feet (91cm) above if within 10 feet  | 
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  | (3m) horizontally** | 
L = Clearance above paved sidewalk or paved diveway located  | 7 feet (2.13m)‡ | 7 feet (2.13m)‡  | 
on public property | 
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M = Clearance under veranda, porch, deck or balcony  | 12 inches (30cm)*‡  | 12 inches (30cm)‡  | 
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N = Depth of Alcove (Maximum)  | 6 feet (1.83m)*  | 6 feet (1.83m)**  | 
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O = Clearance to Termination (Alcove)  | 6 inches (15.2mm)*  | 6 inches (15.2mm)**  | 
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P = Width of Alcove (Minimum)  | 3 feet (91cm)*  | 3 feet (91cm)*  | 
Q = Clearance to Combustible Above (Alcove)  | 18 inches (457mm)*  | 18 inches (457mm)**  | 
* In accordance with the current   | 
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** In accordance with the curent ANSI SZ223.1/NFPA 54 National Fuel Gas Codes.  | 
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*** Clearance required to vinyl soffit material - 30 inches (76cm) minimum.  | 
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‡ A vent shall not terminate directly above a sidewalk or paved driveway which is located between two single family dwellings and serves both  | ||
dwellings. | 
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*‡ Only permitted if veranda, porch, deck or balcony is fully open on a minimum 2 sides beneath the floor:  | 
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Figure 8  | 
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NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.  | 7  |