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VCG Designer Series • DSR36 Installation Manual • 4012-130 • Rev A • 02/20/15
C. Construct the Chase
A chase is a vertical boxlike structure built to enclose the
fireplace and/or its vent system. Vertical chimneys that
run on the outside of a building must be installed inside a
chase.
In cold climates, Vermont Castings Group recommends
that the chase be well insulated using batt type insulation
between the joists.
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/
attic shields 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 3.3.)
Vapor and air infiltration barriers should be installed in the
chase as per regional codes for the rest of the home. Ad
-
ditionally, Vermont Castings Group recommends that the
inside surfaces be drywalled and taped (or the use of an
equivalent method) for maximum air tightness.
Holes and other openings should be caulked with high
temperature caulk or stuffed with unfaced fiberglass insu
-
lation.
Attic
Insulation
Shield
Chimney
Ceiling
Firestop
Tabs
False Ceiling
False Ceiling
Insulation
Insulation
Ceilng
Firestop
Metal Chase Top
Round Termination Cap
False Ceiling
Figure 3.3 Chase Assembly
1
2
1. Chimney offset through exterior wall and
enclosed in chase.
2. Chase constructed on roof.
Figure 3.4 Chase Constructions
• 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.
• In constructing the chase, several factors must be
considered:
-
Maintain a 2 in. (51 mm) air space around the
chimney.
- The chase top must be constructed of non-
combustible material.
- In cold climates, a firestop spacer and attic insulation
shield 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.
- In cold climates, the walls of the chase should be
insulated to the level of the false ceiling as shown in
Figure 3.3. This will help reduce heat loss from the
home around the fireplace.
Chase applications are shown in Figure 3.4.
WARNING! You must install false ceilings and ceil-
ing 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 min-
imum 2 in. (51 mm) air space clearance to insula
-
tion 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.
