User guide

17
the centerline of the venting system
on the ceiling and drill a small hole
through the ceiling and roof at this
point. From the roof, locate the drill
hole and mark the outline of the
Cathedral Ceiling Support Box.
Step 3. Remove shingles or other
roof covering as necessary to cut the
rectangular hole for the Support Box
(refer to Table 1 for dimensions).
Cut the hole 1/8-inch larger than the
Support Box outline.
Step 4. Lower the Support Box
through the hole in the roof until
Support Box protrudes at least
2-inches below the low side of the
ceiling (Fig. 20). Align the Support
Box both vertically and horizontally
with a level. Temporarily tack the
Support Box in place through
the inside walls and into the roof
sheathing.
Step 5. Using tin snips, cut the
Support Box from the top corners
down to the rooine, and fold the
resulting aps over the roof sheathing.
The aps may be trimmed as needed
(Fig. 21). Before nailing it to the roof,
run a bead of non-hardening sealant
around the Support Box, to make a
seal between the Support Box and
the roof. Clean out any combustible
material from inside the Support Box.
Step 6. Follow Steps 4 and 5
(page 14) of the Vertical Installation
Instructions.
Step 7. Place the Support Clamp
(provided with the Support Box) inside
the Support Box (at the bottom),
and secure to the Pipe Section.
The Clamp allows the Support Box
to support the weight of the Pipe


SUPPORT
BOX
CATHEDRAL
CEILING
SCREWS
TRIM
CEILING
OVERLAP

LEVEL
CATHEDRAL
CEILING
FINISHED
CEILING
2' MIN
BELOW
CUT HOLE 1/8"
LARGER THAN
SUPPORT BOX
SUPPORT BOX