Relining Old Chimneys, continued
Safety is a key consideration in our chimney restoration
projects. We've learned that taking a little extra time during
setup to provide solid scaffolding and good access allows us to
work in a more relaxed manner, helping us to concentrate on the
tasks at hand. During the restoration process, a lot of effort
goes into gaining safe access to roofs and chimney tops. We try
not to nail anything into the roof itself; instead, we hang the
majority of our scaffolding from ridges and peaks using systems
like the Ultimate Ridge Hooks (Deer Hill Enterprises,
800/588-9660) and Vanguard Chimney Brackets (Lynn Ladder
& Scaffolding, 800/225-2510). If necessary, we will
build up beams to span valleys, anchor them to lumber or
ladders hung from ridge hooks, and bolt our scaffolding to the
beams (Figure 3).
Figure 3.Solid, well-thought-out scaffolding
provides a sense of security as well as a safe place to work.
The chimney has been wrapped with plastic stretch wrap to help
it resist the pressure of the fluid mortar that will be pumped
around the inflatable formers.
Dust control. Most of our
projects take place in occupied houses, so we also take care to
protect both the house and its contents with well-placed
runners and drop cloths. To control dust, we screen off our
work areas with poly Zip Walls (800/718-2255,
www.zipwall.com) and use powerful
dust-collection vacuums while doing demolition or other dusty
work. We've had very good results with the August West
Sootsweeper II (available from Copperfield Chimney Supply,
800/247-3305, www.copperfield.com), which is a
high-powered vacuum manufactured for chimney sweeps. Although
it isn't listed as a HEPA system, the manufacturer claims that
it will filter out particles as small as .5 microns and move
350 cfm. We use it by putting the hose inside the fireplace so
it sucks up the dust laden air before it has a chance to
spread. To reduce indoor noise, as well as to prevent any dust
particles that may make it past the filter from being exhausted
in the house, we keep the vacuum itself outdoors whenever
possible, running a 3-inch or larger flexible hose to the work
area. To protect ourselves during chimney sweeping and
demolition, we wear full-face respirators and disposable
coveralls (Figure 4).
Figure 4.Tyvek coveralls and full-face respirators
protect workers from potentially carcinogenic
Demolition and Temporary
Many of the older, unlined chimneys in our area were built in
the early 1900s and are separated into multiple flues with
freestanding brick wythes that aren't keyed into the chimney
walls in any way. Weathering and erosion of the mortar leave
them very unstable. Homeowners often realize they have a
problem when they start finding loose bricks from a collapsing
wythe in their fireplaces. These deteriorated wythes must be
removed before any liners can be installed.
Take it from the top. We
remove as much of the wythes as we can from above. This is easy
at first, because the topmost courses can be reached by hand.
Once we get beyond arm's length, we use a variety of hand tools
that can be mounted on bull-float handles. We also use the
Chamber Chipper tool from Golden Manufacturing (800/446-5354,
www.chimneys.com/goldenflue), which is an
inline air hammer mounted on a shaft of 3/4-inch galvanized
pipe. The piston is lowered into the chimney, and the control
stays at the top (see photo at top of page 1). The chipper can
be extended as long as 40 feet, although we find it difficult
to control when it's asked to reach beyond 20 feet or so.
The deteriorated bricks that are chipped loose simply fall to
the bottom of the chimney into the fireplace firebox, which is
padded with plywood, temporarily closed at the front, and
fitted with a vacuum hose to control dust (Figure 5).
Figure 5.A plywood covering over the front of the
fireplace contains broken masonry that falls from the chimney
during demolition, and an efficient vacuum filters out dust
before it can infiltrate the living space (top). The
accumulated brick and mortar fragments are removed once the
demo phase is complete (bottom).
In a two- or three-story house, it can be difficult to get all
the way from the roof to the ground floor. If the firebox in an
upstairs chimney is deteriorated, we'll often remove it and
work our way down through the fireplace opening. When the
demolition phase is done, we build a solid new firebox.
Ho, ho, ho. If the chimney
is large enough, it's often easiest to climb into the chimney
from the rooftop by extending the scaffolding out over the
chimney and then hanging a steel fire escape ladder from it
(Figure 6). Workers entering the chimney wear respirators, hard
hats, and safety harnesses. A vacuum in the fireplace below
pulls fresh air down the chimney around the worker and removes
dust to allow better visibility.
Figure 6.If the size of the chimney permits, a
worker can climb into it from above to dislodge deteriorated
wythes, providing the space needed for the new poured liner
(top). A metal fire escape ladder fastened to the rooftop
scaffolding provides safe and convenient access (bottom).
Openings in the chimney wall, like the unused stovepipe thimble
visible in the photo at left, must be bricked up before the
liner is poured, or a disastrous blowout can
During this part of the job, we also keep an eye out for
hidden openings in the chimney. Occasionally, for example,
we'll find an old stovepipe thimble that was never bricked up
but got covered with wallpaper. Such problem areas have to be
repaired before the liner mix is poured, or it will blow out
into wall cavities or living spaces.
Strapping and wrapping.
During the pour, the chimney is subject to a great deal of
hydraulic pressure from the wet liner mix. Unless that's taken
into account, the result can be a disastrous blowout. Because
the upper portion of a chimney is exposed to the weather, it's
often much weaker than the lower portion. We frequently tear
deteriorated old chimneys down to the roofline and rebuild them
in the original style. Where weakened sections are accessible
from inside the house, we reinforce them with sheets of plywood
cut to the dimensions of the chimney and secured with
ratcheting cargo straps (Figure 7).
Figure 7.The freshly poured liner mix exerts
considerable pressure on the surrounding brick, so tender old
masonry is compressively reinforced with plywood and ratcheting
cargo straps. Plywood and straps will be removed once the new
poured liner has set up.
Another method we often use is to wrap the chimney with
several layers of stretch-wrap film -- the same material used
for securing material to shipping pallets. We buy this from a
safety products supplier in 18-inch-wide rolls. When tightly
wound around the chimney, it provides enough compression to
resist the outward pressure of the wet liner mix.