WALL PASS-THROUGHS
When your installation unavoidably requires the
chimney connector to pass through a combustible wall
to reach the chimney, always consult your local
building officials, and be sure any materials to be used
have been tested and listed for wall pass-throughs.
In the U.S.
The National Fire Protection Associations publication,
NFPA 211,
Standard for Chimneys, Fireplaces,
Vents and Solid Fuel Burning Appliances
permits
four methods for passing through a combustible wall.
Before proceeding with any method be sure to consult
with your local building officials to discuss any local
code requirements.
Common Method
When passing through a combustible wall to a
masonry chimney this method requires the removal
of all combustible materials from at least 12 around
the chimney connectors proposed location. With a 6
round liner the minimum area required would be 31
x 31 square.
The space is then filled with at least 12 of brick
around a fireclay liner. Remember, the liner must be
ASTM C35 or equivalent, with a minimum wall
thickness of 5/8.
It is important to remember to locate the pass-through
at least 18 from the ceiling for proper clearance to
combustibles.
It will be necessary to cut wall studs, install headers,
and construct a sill frame to maintain the proper
dimensions and to support the weight of the brick.
The bricks must be solid brick with a minimum of
3 ½ thick (4 nominal).
Refractory mortar must be used at the junction of the
chimney and the pass-through liner. The pass-through
liner must not penetrate the chimney liner beyond the
inner surface of the chimney liner. Use extreme care
when constructing the hole in the chimney liner, the
tiles can shatter easily.
See figure 3.
The manufacturers installation instructions must be
followed precisely. Always maintain the proper
clearance to combustibles as established by the pipe
manufacturer. This clearance is usually a minimum
of 2, although it may vary by manufacturer or for
certain chimney components.
Chimney Height
Whether a masonry chimney or prefabricated metal
chimney is used it must be the required height above
the roof line.
The requirement is:
The chimney must be at least 3 feet higher than the
highest point where it passes through the roof and at
least 2 feet higher than the highest part of the roof or
structure that is within 10 feet of the chimney,
measured horizontally.
See figure 2.
Chimneys shorter than 14 feet may not provide
adequate draft. This could result is smoke spilling
into the room from the stove when loading the stove,
or when the door is open. In addition, inadequate
draft can cause back puffing, which is a build up of
gases inside the firebox.
Other times, chimney height can create excessive
draft which can cause high stove temperatures and
short burn times. Excessive drafts can be corrected
by installing a butterfly damper.If you suspect you
have a draft problem, consult your dealer.
6
FIGURE 2
