18
Quadra-Fire • Topaz • 7009-113 Rev. Q • 6/14
2. Cathedral Ceiling
Level
Cathedral Ceiling
Support Box
2 in. (51mm)
Min. below
finished ceiling
Cut hole 1/8 in. (3mm)
greater in size than
pattern of support box
as it is projected onto
roof line
Figure 5.17
Figure 5.18
Step 1.
Follow installation Steps 1 and 2 under vertical installation
section, page 15.
Step 2.
Using the plumb-bob, mark the center line 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. Cut the hole 1/8 in.
(3mm) larger than the support box outline.
Step 4.
Lower the support box through the hole in the roof until the
bottom of the support box protrudes at least 2 in. (51mm)
below the ceiling (
Figure 5.17
). 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 roofline, and fold the resulting flaps over the
roof sheathing (
Figure 5.18
). Before nailing it to the roof,
run a bead of non-hardening mastic around the top edges
of the support box to make a seal between it and the roof.
Clean out any combustible material from inside the support
box.
Step 6.
Complete the cathedral ceiling installation by following the
same procedures outlined in steps 7 through 9 for vertical
installations, pages 16-17.
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 sections. Continue to add pipe sections
until you are above the roofline.
Cathedral
Ceiling
Trim Collar
Screws
Support
Box
Step 8.
Install the black trim collar around the outside of the cathedral
ceiling support box (
Figure 5.19
). The two pieces of the trim
collar slide over one another to allow for easy adjustment
around the support box. Using the six screws provided,
secure the four corners and the overlapping sections of the
trim collar to the ceiling. You may want to predrill the holes for
the overlapped sections for ease of installation.
Figure 5.19
