Venting Installation
Continued
Screws
B
A
Figure 9 - Elbow Offset
Firestop Spacers
Firestop spacers are required at each point where the chimney penetrates a floor space. Their purpose is to establish and maintain the required clearance between the chimney and the combustible materials. When the pipe passes through a framed opening into a living space above, the firestop must be placed onto the ceiling from below as shown in Figure 10.
Penetrating the roof
To maintain a 1" clearance to the pipe on a roof with a pitch, a rectangular opening must be cut.
1.Determine the center point through which the pipe will penetrate the roof.
2.Determine the center point of the roof. Pitch is the distance the roof drops over a given span, usually 12". A 6/12 pitch means that the roof drops 6" for each 12" one measure horizontally down from the roof rafters.
3.Use the roof opening chart (Figure 12) to determine the correct opening length and flashing required.
4.Remove the shingles around the opening measured. Cut out this section.
5.Add the next sections of the pipe until the end penetrates the roof line. Check to see that the proper clearances are maintained. Extend chimney by adding sections of double wall pipe until pipe is minimum of 30" above the highest point of the roof cutout. Termination and chimney must extend a minimum of 36" above the highest point where it passes through the roof.
They also provide complete separation from one floor space to another or attic space as required by most codes. When the double wall pipe passes through a framed opening into an attic space, the firestop must be placed into an attic floor as shown in Figure 11.
Existing
Ceiling
Frame
Firestop
Spacer
19.5" Min.
2" Min.
2" Min. 
30" Min.
2" Min.
Opening "A"
Screws or Staples (Min. of 8)
Figure 10 - Firestop Spacer with Living
Space Above Ceiling
Screws or Staples
Firestop(Min. of 8) Spacer 
Existing |
Ceiling |
Frame |
Figure 11 - Firestop Spacer with Attic
Space Above Ceiling
Pitch | Slope | Opening | Used Flashing | |
|
| "A" Max. | Model No. | |
Flat | 0° | 19.5" | ||
26.6° | 22" | |||
6/12- | 45.0° | 27" | ||
12/12 | ||||
|
|
|
Figure 12 - Roof Opening Measurements
Flashing installation
Determine the flashing to be used with the roof opening chart. Slide flashing over pipe until base is flat against roof. Replace as many shingles as needed to cover exposed area and flashing base. Secure in position by nailing through shingles (see Figure 13, page 10). DO NOT NAIL THROUGH FLASHING CONE.
