10
Install a Firestop Radiation Shield at each floor penetration above the ceiling support including the opening into
the attic. The Firestop Radiation Shield is installed from the bottom of the ceiling/floor rough opening with the
tube section of the Firestop pointing upwards. Secure the Firestop to the rough opening with a minimum of one
8-penny nail or one #8 x 1 ½” wood screw at each corner. Adjust the inner tube of the fire stop upward to cover
all framing of the floor/ceiling rough opening. Secure the inner tube to the outer tube using at least three sheet
metal screws.
Note: In the attic opening, a Firestop and an attic insulation shield extension will be used. A
Firestop is not to be installed at the roof penetration.
Step 5
The Roof Opening: Use a plumb bob to locate the center of the roof opening as it corresponds to the
center of the opening below. Mark the location on the underside of the roof sheeting. Drill a hole using a ¼” bit
through the sheeting and shingles in order to have an exterior visible reference. A reciprocating saw is helpful
in cutting the opening a minimum of 4-inches larger than the chimney’s outside diameter. This maintains the
required minimum of 2-inch air space clearance around the chimney.
Note: The opening is round for flat roofs,
but will be oval in shape for pitched roofs.
Enclosures: In a multi-story
installation, if the chimney passes
through an occupied space, which
includes closets and occupied
attics, an enclosure must be
constructed around the chimney.
The enclosure may be constructed
with standard framing and
sheeting materials such as sheet
rock or plywood. Be sure to
maintain 2-inches of air space
between the chimney and
combustibles.
Step 4
Frame Additional Openings
(for multi-story installations):
This is a required step for multi-floor
installations where the chimney must
pass through additional ceilings (floors).
Using dimensions from Table 1 (p.8),
frame out each ceiling (floor) opening
above the support box. Use a plumb bob
to assist in locating the corresponding
four corners of the opening above. (If
elbows are used to offset an obstruction
refer to page 12).
