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For Vertical Terminations - To locate the vent and install
the vent sections:
• Locate and mark the vent centerpoint on the underside
of the roof, and drive a nail through the centerpoint.
• Make the outline of the roof hole around the centerpoint
nail.
• The size of the roof hole framing dimensions depend on
the pitch of the roof. There MUST BE a 1-inch (25.4mm)
clearance from the vertical vent pipe to combustible mate-
rials.
• Mark the roof hole accordingly.
• Cover the opening of the installed vent pipes.
• Cut and frame the roof hole.
• Use framing lumber the same size as the roof rafters
and install the frame securely. Flashing anchored to the
frame must withstand heavy winds.
• Continue to install concentric vent sections up through
the roof hole (for inside vent installations) or up past the
roof line until you reach the appropriate distance above
the roof (for outside terminations).
WARNING: MAJOR U.S. BUILDING CODES
!
SPECIFY MINIMUM CHIMNEY AND/OR VENT
HEIGHT ABOVE THE ROOF TOP. THESE MINIMUM
HEIGHTS ARE NECESSARY IN THE INTEREST OF
SAFETY. SEE THE FOLLOWING DIAGRAM FOR
MINIMUM HEIGHTS, PROVIDED THE TERMINA-
TION CAP IS AT LEAST 20 INCHES FROM A VER-
TICAL WALL AND 2-FEET BELOW A HORIZONTAL
OVERHANG.
NOTE: This also pertains to vertical vent systems in-
stalled on the outside of the building.
PV-FLEX
PIPE
Figure 20.
B-VENT
COMPONENT
To seal the roof hole, and to divert rain and snow from the
vent system:
• Attach a flashing to the roof using nails, and use a non-
hardening mastic around the edges of the flashing base
where it meets the roof.
• Attach a storm collar over the flashing joint to form a
water-tight seal. Place non-hardening mastic around the
joint, between the storm collar and the vertical pipe.
• Slide the termination cap over the end of the vent pipe
and snap into place.
2 FT.
MIN.
TERMINATION
CAP
Roof Pitch
flat to 6/12
6/12 to 7/12
over 7/12 to 8/12
over 8/12 to 9/12
over 9/12 to 10/12
over 10/12 to 11/12
over 11/12 to 12/12
over 12/12 to 14/12
over 14/12 to 16/12
over 16/12 to 18/12
over 18/12 to 20/12
over 20/12 to 21/12
Figure 21. Minimum Height from Roof to
Lowest Discharge Opening
21
HORIZONTAL
OVERHANG
20 INCH MIN.
VERTICAL
WALL
LOWEST
DISCHARGE
OPENING
X
12
ROOF PITCH
IS X/ 12
H (MIN.) - MINIMUM HEIGHT FROM ROOF
TO LOWEST DISCHARGE OPENING
H (min.) ft.
1.0
1.25
1.5
2.0
2.5
3.25
4.0
5.0
6.0
7.0
7.5
8.0
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