Cutting the Hole
Cover fireplace collar opening and cut proper sized chimney hole in chimney. (Fig. 10 & 11)
Framing the Ceiling Hole
Frame the ceiling chimney hole as shown in Figure 11. It is good practice to use framing lumber that is the same size as the ceiling joists; this is a requirement at attic level.
The following table gives firestop spacer model num- bers:
CHIMNEY HOLE SIZE | FP548b | ||
| Angle of Chimney at Ceiling | ||
Size of Chimney |
|
| |
Vertical | 30˚ | ||
11" CF | FS2A | FS6A | |
17 ¹⁄₂" x 17 ¹⁄₂" | 17 ⁷⁄₈" x 29 ⁵⁄₈" | ||
| |||
|
|
| |
Fig. 10 Ceiling chimney hole size necessary for installing firestop spacer.
The inside dimension of the frame must be the same as the hole size selected from Figure 10 in order to provide the required 2 inches of air space between the outside diameter of the chimney and the edges of the framed ceiling hole.
ODSHR Series
Existing | 17¹⁄₂" | 17¹⁄₂" | |
Ceiling | |||
|
| ||
Joists |
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| |
|
| Chimney | |
|
| Hole | |
New Framing |
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| |
Members |
|
| |
|
| FP551b |
Fig. 11 Typical frame for ceiling chimney hole.
20002264 | 9 |