9
plumbing down to the center of the chimney. Drive a
nail into the roof to mark the center.
E. Measure to all sides of the nail and mark the re-
quired opening, and then cut a hole in the roof. Re-
member that the hole is measured on the horizontal,
and then projected to the roof. The hole may then be
larger, depending on the pitch of the roof. See Fig-
ure 21.
F. Frame the opening, ensuring that the recom-
mended minimum clearance to combustibles by the
chimney pipe manufacturer exists between the roof
and the chimney, ensuring that distance is maintained
all the way around.
WARNING: DO NOT PACK REQUIRED AIR
SPACES WITH INSULATION OR
OTHER MATERIALS.
G. Continue to add pipe sections, extending the
chimney through the roof.
H. A wood chase may be constructed around the
exposed chimney for aesthetic effect. Ensure the
minimum recommended clearances to combustibles
specified by the metal chimney pipe manufacturer
are maintained inside the chase.
I. Install roof flashing appropriate to the roof pitch,
and any other pipe accessories, per the pipe manufac-
turer’s instructions.
J. Install the appropriate chimney cap for the pipe
being used.
4.3 Height of Chimney
Figure 25 illustrates the proper height of the chimney
top. Correct height depends on the chimney’s location
on the roof and distance from the peak of the roof.
Surrounding trees, other buildings and hills may also
be a consideration.
If the chimney top is not high enough, unusual
downdrafts may occur, resulting in undesired smoke
Figure 24. Metal Chimney Construction
Figure 25. Chimney Height
Summary of Contents for NA36IND
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