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VENTING INSTALLATION
Continued
4. Connect a section of pipe and extend
up through hole. If an offset is needed to
avoid obstructions, you must support vent
pipe every 3 feet. Use wall straps for this
purpose (see Figure 24, page 17). When-
ever possible, use 45° elbows instead of
90° elbows. The 45° elbow offers less
restriction to the flow of flue gases and
intake air.
5. Place flashing over pipe section(s) ex
-
tending through roof. Apply a bead of
silicone or roof sealer to the bottom flange
of flashing and secure base of flashing
to roof and framing with roofing nails. Be
sure roofing material overlaps top edge of
flashing as shown in Figure 24, page 17.
There must be a 1" clearance from vent
pipe to combustible materials.
6. Continue to add pipe sections until the
height of vent cap meets the minimum
building code requirements described in
Figure 14, page 12.
Note: You must increase vent height for
steep roof pitches. Nearby trees, adjoin-
ing roof lines, steep pitched roofs, and
other similar factors may cause poor
draft or down-draft condition (see Figure
24, page 17). Increasing vent height may
solve this problem.
7. Apply a bead of sealer to the upper edge
of flashing collar. Slide storm collar over
pipe and down to top edge of flashing.
Apply a second bead of silicone or roof
sealer around remaining seam of storm
collar. Twist-lock vent cap onto last section
of vent pipe. Finish sealing flange around
roofing material with roofing sealer.
Note: If vent pipe passes through any oc-
cupied areas above the first floor, including
storage spaces and closets, you must enclose
pipe. You may frame and sheetrock enclosure
with standard construction material. Make
sure and meet the minimum allowable clear-
ances to combustibles. Do not fill any required
air spaces with insulation.
Figure 27 - Cathedral Ceiling Support
Box Installation
Cut hole 1/8"
larger than
support box when
projected onto roof line
2" minimum below
finished ceiling
Cathedral
ceiling
support box
Level
Cathedral Ceiling Installation
1. Remove shingles or other roof covering as
necessary to cut rectangular hole for sup-
port box. Mark outline of cathedral ceiling
support box on roof sheathing using the
locating hole as a center point.
2. Cut hole 1/8" larger than the support box
outline (see Figure 27).
3. Lower support box through hole in roof
until bottom of box extends at least 2"
below ceiling (see Figure 27). Align sup-
port box vertically and horizontally using
a level. Temporarily tack support box in
place through inside walls and into roof
sheathing.
4. Using tin snips, cut support box from
top corners down to roof line and fold
resulting flaps over roof sheathing (see
Figure 28). Apply a bead of non-hardening
mastic around top edges of support box to
make a seal between box and roof. Nail
in place with roofing nails. Remove any
combustible material that might be inside
of support box.
5. Complete cathedral ceiling installation
by following the same procedures out-
lined in steps 2 through 7 for
Flat Ceiling
Installation,
page 18
.
Non-hardening
Mastic under all
edges of support
box before nailing
Figure 28 - Installed Cathedral Ceiling
Support Box
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