M&G DuraVent DuraTech® 5-8 - Manual (Page 15)

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ceiling and roof exists, as shown in Figure
18 (Low Attic), first cut and frame a ceiling
opening as described in Ceiling-Supported
Installations (Step 2). Refer to Table 2 for
clearance and framing specifications. If it is
desired to install through a cathedral ceiling
(Fig 19), then the hole is cut in the roof.
3. Install Support Box: Slip the Square
Support Box, Reduced Clearance Support
Box, or the CAS Ceiling Support into the
framed opening so the square portion projects
at least 2 inches below the finished ceiling and
rafters (bottom of round portion is 5” below),
and extends above the ceiling to framing or
decking materials to which it can be nailed.
Level the Support Box, and slit the corners
to the roofline where they extend beyond it.
Bend the flaps (created by the slitting) flush
with the roof, and nail the Support Box to the
roof or framing with at least three (3) 8-penny
nails, or (3) 1-1/2”, #8 screws, per side (Fig
20). Be sure to keep the Support Box level.
Screw the trim sections into the ceiling (Fig 6).
4. Complete Installation: Refer to Steps 7,
9 & 10 in the Ceiling Supported Installation
section to complete the Roof Supported
installation.
Figure 20
Figure 21
(2) A Roof Support is also used in installations
where there is a cathedral ceiling, and a
Square Ceiling Support is not desired. The
Roof Support allows the DuraTech chimney
to come down into the room below the level
of the ceiling (Fig 21). The Roof Support can
support a maximum of 45 feet of DuraTech
Chimney total, and maximum of 20 feet below
the support. If a taller stack of DuraTech
Chimney is required, you must use a Square
Ceiling Support Box instead.
1. Cut and frame opening to provide a
minimum 2” clearance on all sides of the
chimney pipe. Note: Opening in finished
ceiling should be circular/oval in order for it to
be covered by Trim Collar.
2. Bolt on the Roof Support Brackets to
the Roof Support Band using the supplied
ROOF SUPPORT
TRIM COLLAR
FINISHING COLLAR
DURABLACK
SLIP CONNECTOR
USE 4 NAILS (OR
SCREWS) ON
EACH SIDE OF
SUPPORT
ROOF SUPPORT
(SUPPORT
BRACKETS AND
BAND)
SECURE ROOF
SUPPORT BAND TO
CHIMNEY USING
4 SHEET METAL
SCREWS
TIGHTEN BOLT
ON ROOF
SUPPORT BAND.