Putting The Spark Back Into Your Fireplace:
By definition, a "nonworking" masonry fireplace
doesn't have a chimney lining; while it actually
could "work," its operation would be beneath
modern safety standards. (A bare flue provides
poor heat containment and increases the chances
of a chimney fire burning through weak mortar
joints and igniting the framing of a building.)
Double check by sighting down the chimney from
the roof. Occasionally you will find a chimney
with a few liner sections near the top and
bottom. To be more sure that your lining is
complete, lower a drop light from the top of the
chimney.
Get professional help if your roof is made of
slate, terracotta or any other brittle
substances that might crack easily. Likewise,
stay off steep or wet roofs. Also, beware of
electrical entrance wires, wires through trees
and TV antennas. (A chimney sweep or a fireplace
mason will check a chimney lining for about $25.
Be sure to ask that a drop light be used during
the inspection.)
Terra-Cotta Lining:
Terracotta (a type of baked clay) is the
traditional masonry, chimney lining material.
Retrofitting (installing a lining after the
fact) requires breaking into the old chimney
from inside the house and setting in the liners
a messy, expensive job requiring professional
masonry skill.
The liners come in sections that are generally
2feet long and 5/8 -inch thick. The
cross-sectional dimension of the liner is
determined by the square-inch opening of the
fireplace it will serve. The ratio is 10to1 for
a chimney height of 30 feet or less and 12to1
for a height over 30 feet. For example, a
fireplace 30inches wide and 24 inches high
totaling 720 square inches would require a flue
with at least 72 square inches of opening if the
chimney was 30 feet or less in height. (Flue
linings that are installed using a more
restrictive ratio often cause smokey fireplace
operation.)
Lining a fireplace with terracotta also could
involve rebuilding the firebox and smoke chamber
and fitting in a damper ring and plate as well.
You should expect to pay a minimum of about
$1,500 for the masonry work for a two-story
chimney naturally, any framing or plaster
repairs would be extra but sometimes it's
possible to find a relining specialist in a
renovation area who can do the job for
considerably less. In any case, of course, be
sure that whomever you hire can provide you with
a list of previously satisfied homeowners.
Metal Lining (Old School):
Old chimneys can be relined with stainless steel
pipe lowered down the flue (stainless steel is
the only material that will resist the corrosive
effects of creosote.) The sections range in
length from 6 to 36 inches and come in diameters
of 5 to 10 inches. Each section must be held
together with metal screws. This method is only
practical when the chimney is very straight, but
most chimneys have offsets and bends that make
this method a poor consideration.
Metal Lining (New School):
A flexible stainless steel liner is now
available for retrofitting old chimneys. It
comes in diameters from 5 to 8 inches and is fed
down the flue, making it the practical solution
for a sound chimney with bends and offsets. Once
the flue liner is in position, vermiculite
insulation is poured around it from the top and
a cap is secured above the chimney. (This is the
desired lining for any flue servicing a wood
stove since the insulation around the liner
provides a warmer flue with a better draw and
less creosote condensation.) For installation,
expect to pay a professional at least $600 for a
two-story chimney.
WARNING:
No metal lining will resist the corrosive
effects from burning coal. Only terracotta or
masonry will do.
"English" Lining: The so-called English method
involves dropping a cylindrical, inflatable bag
down the flue and sealing off the base of the
chimney. Spacers are set around the bag to keep
it centered and the bag is inflated. A cement
slurry is then pumped in around the bag and
allowed to cure before the bag is deflated and
removed. Expect to pay about from $1,000 to
$1,300 for a two story flue. (This system has
the added benefit of adding strength to the
chimney itself.)
"Aherns" has a chimney lining system that is
somewhat like the English system except that a
metal bell with a vibrator inside it is winched
up through the chimney as special mortar is
poured down on top of it. A ceramic-like second
liner is then applied over the newly set mortar
mix. This would appear to be very effective and
is reported to have been done more than a
million times.
Self Help:
Here is something you can do yourself that costs
a little but takes a lot of energy. First, brush
the chimney very clean and then drop a rope down
to the hearth. Attach the rope to a burlap bag
filled with tire chains (on the bottom of the
bag) and tightly balled newsprint (on top of the
chains), making sure the bag is just large
enough to fit snugly into the flue. As the bag
is inched up, shovel mortar (refractory cement)
on top of it; the cement should adhere to the
sides of the flue. Multiple lifts are required
and the final job should be checked with a drop
light lowered down the flue. Have the local fire
marshal or a qualified chimney sweep survey your
work prior to lighting the first fire.
Final Touch:
Whether you do it yourself or hire a
professional, the best way to check if your
chimney is completely sealed is to light a smoke
candle above the damper, cover the top of the
flue with a wet blanket and survey inside and
outside the house for smoke leaks.