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26 69D0023
VENT INSTALLATION
3. Cut a hole in the roof using the locating hole as a center point. (Cover any exposed open vent pipes before cutting hole in
roof). The 9
1
/2"x9
1/
2
" (241mm x 241mm) hole must be measured on the horizontal. Actual length may be larger depending
on the pitch of the roof. There must be a 1" minimum clearance from the vent pipe to combustible materials. (Insulation
should be considered a combustible material).
4. Connect a section of pipe and extend up through the hole.
NOTE: If an offset is needed to avoid obstructions, you must support the vent pipe every three (3) feet.
Use wall straps for this purpose. See Figure 28, page 23. Whenever possible, use 45° elbows instead of
90° elbows. The 45° elbow offers less restriction to the flow of the flue gases and intake air.
5. Place the flashing over the pipe section(s) extending through the roof. Secure the base of the flashing to the roof and
framing with roofing nails. Be sure roofing material overlaps the top edge of the flashing. There must be a 1" clearance
from the vent pipe to combustible materials.
6. Continue to add pipe sections until the height of the vent cap meets the minimum building code requirements.
NOTE: You must increase vent height for steep roof pitches. Nearby trees, adjoining roof lines, steep
pitched roofs, and other similar factors may cause poor draft or down-drafting in high winds. Increasing
the vent height may solve this problem.
NOTE: If the vent pipe passes through any occupied areas above the first floor, including storage spaces
and closets, you must enclose pipe. You may frame and sheetrock the enclosure with standard construction
material. Make sure to meet the minimum allowable clearances to combustibles. Do not fill any of the
required clearance spaces with insulation.
Figure 33 - Cathedral Ceiling Support Box
Installation
Figure 34 - Installed Cathedral Ceiling
Support Box
CATHEDRAL CEILING INSTALLATION
IMPORTANT: Review all information on previous
page before planning this installation. Cathedral
ceiling installations can be very tricky.
1. Remove shingles or other roof covering as necessary to
cut the rectangular hole for the support box. Mark the
outline of the cathedral ceiling support box on the roof
sheathing using the locating hole as a center point.
2. Cut the hole 1/ 8" larger than the support box outline. See
Figure 33.
3. Lower the support box through the hole in the roof until
the bottom of the box extends at least 2" ( mm) below
the ceiling. See Figure 33. Align the support box verti-
cally and horizontally using a level. Temporarily tack the
support box in place through the inside walls and into the
roof sheeting.
4. Using tin snips, cut the support box from the top corners
down to the roof line and fold the resulting flaps over the
roof sheeting. See Figure 34. Apply a bead of non-hard-
ening mastic around the top edges of the support box to
make a seal between the box and the roof. Nail in place
with roofing nails. Remove any combustible material that
might be inside the support box.
5. Complete the cathedral ceiling installation by following
the same procedures outlines in steps 2 through 6 for Flat
Ceiling Installation, page 25 and above.
Level
Cathedral
Ceiling
Support Box
2" Minimum
Below
Finished
Ceiling
Cut Hole 1/8"
Larger than
Support Box when
Projected onto
Roof line.
Apply Non-hardening
Mastic Under all Edges
of Support Box before
Nailing