DuraVent DuraTech 10-24 Installation - Manual (Page 9)

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properly). Level the Support Box and secure
it to the framing using at least three 8-penny
nails per side (min. of 12 total). Wrap the
straps of the Support Box around the framing
members (Fig 4), and secure with (2) 8-penny
nails per side (eight nails total). Alternatively,
you may use 1-1/2” #8 wood screws (min. of
12 total for the Support Box, and 8 total for
the straps), instead of nails. Next, secure
the round or square Trim Collar to the ceiling/
framing members using (4) 1” long, round-
head wood screws.
4. Frame Openings: Frame openings in
each ceiling or floor above the Support Box
(Fig 6). These openings are to hold the
Firestop Radiation Shield and Attic Insulation
Shield. Locate each opening by dropping a
plumb bob to the four corners of the opening
below. Maintain the minimum clearances and
dimensions as specified in Table 2. If Elbows
must be used to avoid an obstruction, refer to
the Offset Elbow Installation section.
5. Cut Roof Opening: Cut an opening in the
roof directly above the opening below, and
at least 4 inches larger than the chimney’s
outside diameter to provide at least a
2-inch clearance all around the chimney.
The chimney must be centered within this
Figure 7
Table 2
Inside Square Framing Dimensions
(X" x X")
Chimney Diameter 10" 12" 14" 16" 18" 20" 22" 24"
ceiling SuppoRt Box
16 1/4" 18 1/4" 20 1/4" 22-1/4" na na na na
wall thimBle
16" 18" 20" 22" na na na na
FiReStop Radiation Shield
16" 18" 20" 22" 24 1/4" 26 1/4" 28 1/4" 30 1/4"
attic inSulation Shield
16 1/4" 18 1/4" 20 1/4" 22 1/4" 24 1/4" 26 1/4" 28 1/4" 30 1/4"
opening and maintain the 2-inch clearance to
combustibles.
6. Install Firestop Radiation Shield: A Firestop
Radiation Shield is required in multistory
installations at each floor penetration above
that where the Support Box is located.
Example: in a multistory home where the
appliance is on the ground floor (Support
Box is in the 1st floor ceiling), you would
need a Firestop Radiation Shield at the 2nd
floor ceiling, and at the 3rd floor ceiling, etc.,
FRAMING
FIRESTOP
RADIATION
SHIELD