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56131H
17
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 15). 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 15.
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 10.
.
Note: You must increase vent height for
steep roof pitches. Nearby trees, adjoining
rooflines, steep pitched roofs, and other
similar factors may cause poor draft or
down-draft condition (see Figure 24, page
15). 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 roofline
".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.
.. Cut.hole.1/8".larger.than.the.support.box.
outline.(see.Figure.7).
3.. Lower. support. box. through. hole. in. roof.
until. bottom. of. box. extends. at. least. ".
below.ceiling.(see.Figure.7)..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 roofline and fold result
-
ing flaps over roof sheathing (see Figure
8)..Apply.a.bead.of.non-hardening.mas-
tic. 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.outlined.in.
steps..through.7.for.
Flat Ceiling Installa-
tion,
page.16
.
Non-hardening.
Mastic.under.all.
edges.of.support.
box.before.nailing
Figure 28 - Installed Cathedral Ceiling
Support Box