Installation Guide
PG 10 
attic areas where this shield cannot fit, a Square Ceiling Support Box, (which are 
available in heights of 11”, 24”, and 36”), can be used instead of an Attic 
Insulation Shield, provided it reaches through the roof; refer to the Roof 
Supported Installation section on page 14. If the chimney is fully enclosed 
through the attic, an Attic Insulation Shield is not required. 
Where the chimney passes into the attic, install the Attic Insulation Shield as 
follows: 
a. If the Firestop Radiation Shield extends above the attic floor, no 
modifications are necessary. The Firestop Radiation Shield will fit inside 
the Attic Insulation Shield. If the Square Ceiling Support Box extends into 
the attic above the framing you will need to trim the box down. 
b. Assemble Chimney Sections until at least 18 inches of chimney extends 
above the Firestop Radiation Shield or Square Ceiling Support Box. 
c. When applicable extend the Firestop Radiation Shield tube extension 
(keep at least 1” overlap), and secure in place using sheet metal screws. 
d. Slip the Attic Insulation Shield over the chimney pipe until the base sits 
squarely on the framed opening (Fig 6 & 9). 
e. Secure the Attic Insulation Shield to the top of the framed opening using at 
least (3) 8-penny nails or (3) #8, 1-½” wood screws per side (Fig 9). 
f. Wrap the Collar of the Attic Insulation Shield around the chimney and 
fasten it loosely with the supplied hardware. Slide the Collar down to meet 
the Attic Insulation Shield. Tighten the hardware to secure the Collar. 
9. Attach Roof Flashing: In new construction, assemble the Chimney Sections to 
a point above the roof, then slip the Roof Flashing over the chimney. On an 
existing roof, center and install the Roof Flashing before extending the chimney 
above the roof. Allow space to permit sliding the next Chimney Section up 
through the Roof Flashing. Always ensure the chimney remains vertical (use a 
level), and that at least a 2 inch clearance to combustible materials is maintained 
all around. Install the upper edge of the Roof Flashing under the roofing material 
(shingles). Nail to the roof along the upper edge and down each side with 1 inch 
roof nails. Do not nail the lower edge of the Flashing. Be sure to follow local 
building practices as needed. Seal all nail heads with a non-hardening 
waterproof sealant. On flat or tarred and gravel roofs, nail and seal the Flat Roof 
Flashing to the roof on all sides of the roofing compound. Do not put screws 
through the Roof Flashing into the Chimney Pipe. 
10.Finish Top: Apply a high-temperature (500℉), non-hardening waterproof sealant 
around the chimney at the point where the Storm Collar will meet the chimney 
just above the Roof Flashing, and also along the vertical seam of the chimney 
AllFuel HST Inc    www.allfuelhst.com  Toll Free: (833) 326-8368 










