E. Construct the Chase
A chase is a vertical boxlike structure built to enclose the fire- place and/or its vent system. Vertical chimneys that run on the outside of a building must be installed inside a chase.
Construction of the chase may vary with the type of build- ing. These instructions are not substitutes for the require- ments of local building codes. Local building codes MUST be checked.
Chases should be constructed in the manner of all outside walls of the home to prevent cold air drafting problems. The chase should not break the outside building envelope in any manner. All outer walls need to be insulated.
Building codes require false ceiling and ceiling firestops at each floor of the chase or every 10 ft (3.05 m) of clear space to control spread of fire.
Walls, ceiling, base plate and cantilever floor at the first level of the chase should be insulated. See Figure 3.5. Vapor and air infiltration barriers should be installed in the chase as per regional codes for the rest of the home. Additionally, Hearth
&Home Technologies recommends that the inside surfac- es be sheet rocked and taped (or the use of an equivalent method) for maximum air tightness.
Round Termination Cap | |
Metal Chase Top | |
Ceiling | |
Firestop | |
False Ceiling | |
Figure 3.5 | Chase Assembly |
Gas line holes and other openings should be caulked with high temperature caulk or stuffed with unfaced fiberglass in- sulation. If the fireplace is being installed on a cement slab, we recommend that in cold climates, a sheet of plywood or other raised platform be placed underneath to prevent con- ducting cold up into the room.
Three examples of chase applications are shown in Fig- ure 3.6.
1.Fireplace and chimney enclosed in an exterior chase.
2.Chimney offset through exterior wall and enclosed in chase.
3.Chase constructed on roof.
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Figure 3.6 Chase Constructions
F. Chimney Requirements
When planning your fireplace location, the chimney con- struction and necessary clearances must be considered. The fireplace system and chimney components have been tested to provide flexibility in construction. Vertical distances are measured from the base of the fireplace as shown in Figure 5.2.
• | Minimum overall straight height | 14 | (4.27 m) |
• | Minimum height with offset/return | 16.5 ft | (5.03 m) |
• Maximum height | 90 ft | (27.43 m) | |
• Maximum chimney length between an offset | 20 ft | (6.1 m) | |
| and return |
|
|
• Maximum distance between chimney | 35 ft | (10.67 m) | |
| stabilizers |
|
|
• | Double offset/return minimum height | 20 ft | (6.1 m) |
• Maximum unsupported chimney length | 6 ft | (1.83 m) | |
| between the offset and return |
|
|
• Maximum unsupported chimney height above | 35 ft | (10.67 m) | |
| the fireplace |
|
|
• Maximum unsupported chimney above roof | 6 ft | (1.83 m) | |
Note: A maximum of two pairs of offsets and returns may be used.
12 | Heat & Glo • |
