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Continue to assemble chimney sections as
outlined above, making sure that both the
inner and outer pipe sections are locked
together.
When installing double wall snap-lock chimney
together, it is important to assure joint between
chimney sections is locked. Check by pulling
chimney upward after locking. Chimney will not
come apart if properly locked. It is not neces-
sary to add screws to keep chimney together
(exception, see Figure 12, page 8).
ADjUSTABLE FIRESTOP THIMBLE
(FST-A)
The adjustable firestop thimble assembly (FST-A)
is used to provide the necessary air space and
clearance between the chimney pipe and insula-
tion in the attic space of a manufactured home.
To install thimble assembly, determine dis-
tance between ceiling joist and roof framing.
Attach adjustable thimble to firestop spacer so
that assembly will cover the distance. Adjust-
able thimble should be even with or above the
roofline (see Accessories, page 14, for thimble
Insulation
Barrier
Firestop
Adapter Plate (If Needed)
Figure 8 - Attaching Firestop/Thimble
Assembly to Ceiling
56149J
VenTing inSTallaTion
Continued
Roof Line
Thimble Extension
(If Needed)
Adjustable Thimble
Existing
Ceiling Frame
Firestop Spacer
Screws or Staples
(Min. of 8)
Thimble (Open End)
12"
Min.
Screw Holes
Provided
for Thimble
Firestop
Thimble
(Closed End)
www.fmiproducts.com
extensions if a longer thimble is needed).
Sheet metal screws or staples may be used
to attach thimble to firestop spacer.
An opening large enough to allow insertion of
firestop thimble assembly will be required in
the ceiling. Attach firestop/thimble assembly
to ceiling/ceiling joist using screws or staples
as shown in Figure 8. A minimum of 8 screws
or staples should be used.
The firestop thimble assembly should also
be used where there is a cathedral ceiling,
insulation barrier and roof, all in one assembly
in a manufactured home (see Figure 8 and
Figure 7). The FST-A thimble can be used in
any one of three common ceiling pitches; flat,
12"/96" and 30"/144".
An opening big enough to allow the insertion
of the firestop thimble assembly will be re-
quired. This opening depends on the pitch of
your ceiling. If your ceiling is a flat or 12"/96"
pitch, you must use the adapter plate provided
to seal unwanted openings. For 30"/144"
pitch, discard adaptor.
If adapter is needed, secure it onto firestop
using holes provided (see Figure 9). The row
of holes on sides of thimble is provided to allow
for pitch variances. Position firestop assembly
and thimble to desired angle and secure with
screws provided. Insert thimble and firestop
into prepared opening and secure to ceiling
by nailing through firestop flanges. The thimble
should be even with or above the roofline.
Thimble extensions are available (as an option)
when required. See Accessories, page 14.
Use for Flat
Firestop
Pitch Ceiling
Figure 9 - Use a Firestop Thimble
Assembly for Cathedral Ceiling,
Insulation Barrier and Roof
Thimble
12"/96" Pitch
12"
7.13"
96"
30"/144" Pitch
30"
11.77"
144"
Adapter Plate
(For Flat and
12"/96" Pitch
Ceilings Only)
Use for 12"/96"
Pitch Ceiling
7
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