18 45D0028
VENT INSTALLATION
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 18, page 17. 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 ashing over the pipe section(s) extending through the roof. Secure the base of the ashing to the roof and
framing with roong nails. Be sure roong material overlaps the top edge of the ashing as shown in Figure 18, page
17. 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 air spaces with insulation.
Figure 21 - Cathedral Ceiling Support Box
Installation
Figure 22 - 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 21.
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 21. 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 rooine and fold the resulting aps over the
roof sheeting. See Figure 22. 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 roong 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 17 and above.
Level
Cathedral
Ceiling
Support Box
2" Minimum
Below
Finished
Ceiling
Cut Hole 1/8"
Larger than
Support Box when
Projected onto
Roofline.
Apply Non-hardening
Mastic Under all Edges
of Support Box before
Nailing
To Next Page
Loading...
