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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.
In cold climates, it is recommended that the chase be well
insulated using batt type insulation between the joists.
Construction of the chase may vary with the type of building.
These instructions are not substitutes for the requirements 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 (3048 mm) 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 9.1. 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 surfaces be
sheet rocked and taped (or the use of an equivalent method)
for maximum air tightness.
Holes and other openings should be caulked with high tem-
perature caulk or stuffed with unfaced fiber glass insulation.
Ceiling
Firestop
Metal Chase Top
Round Termination Cap
False Ceiling
Insulation in the
outside walls
of the chase
Attic
Insulation
Shield
Chimney
Ceiling
Firestop
Tabs
False Ceiling
False Ceiling
Insulation
Insulation
Storm Collar
Figure 9.1 Chase Assembly
1
2
3
All outside walls should be insulated.
Figure 9.2 Chase Constructions
1. Fireplace and chimney enclosed in an exterior chase.
2. Chimney offset through exterior wall and enclosed in chase.
3. Chase constructed on roof.
b.
In constructing the chase, several factors must be consid-
ered:
1)
Maintain a 2 in. (51 mm) air space around the chimney.
2)
The chase top must be constructed of non-combustible
material.
3)
In cold climates, a firestop spacer should be installed in an
insulated false ceiling at the 8 ft. (2438 mm) level above
the fireplace assembly. This reduces heat loss through
the chase.
4)
In cold climates, the walls of the chase should be insu-
lated to the level of the false ceiling as shown in Figure
9.1. This will help reduce heat loss from the home around
the fireplace.
9
Chase Installations
A. Construct the Chase
a.
The chase is constructed using framing materials much
the same as the walls in your home. A variety of siding
materials may be used including brick, stone, veneer
brick, or standard siding materials.
Three examples of chase applications are shown in Figure 9.2
WARNING!
You must install false ceilings and ceiling
firestops at each floor of the chase or every 10 ft (3.05 m)
to control spread of fire.
WARNING! Risk of Fire! DO NOT
seal area between fire
stop opening and chimney pipe except where they enter the
attic or leave the warm air envelope of the home (use 600
°
F sealant).
WARNING! Risk of Fire!
You must maintain a minimum
2 in. (51 mm) air space clearance to insulation and other
materials surrounding the chimney system.
• Insulation and other materials must be firmly secured to
prevent accidental contact with chimney system.
• The chase must be properly blocked to prevent blown
insulation or other combustibles from entering and
making contact with fireplace or chimney.
• Failure to prevent contact between insulation or other
materials and chimney system may cause overheating
and fire.
