Are Chimney Sealants a Good Idea?
The chimney is
one prominent part of the home that is constantly at the mercy of the
fluctuating weather. As weather patterns shift through the seasons, the baking
sun, rising humidity, driving rain, and deep freeze of the outdoor elements can
take a toll on the brickwork, and while bricks are a naturally resilient
building material, they can still take on a considerable amount of wear damage
over time. One common option for combating the threat of moisture and water is
a brick sealant — but, is a sealant the right idea? Here are the points to keep
in mind before committing to a sealant for your chimney.
Because bricks
are a porous stone material, they naturally have minute pores which can absorb
any moisture that comes into contact with the bricks. Once the liquid moisture
is in the bricks, and the temperature drops, the moisture freezes and expands,
causing larger cracks and spalling. Applying a waterproof sealant creates a
layer of the surface of the bricks that stops the moisture from absorbing into
the brick’s surface. This is the major pro of a sealant — preventing liquid
from entering the brickwork and causing cracks. From here, we need to focus on
the material being used in the sealant.
Circling back
to the porous nature of brick, the small crevices are a necessary element to
maintain the integrity of the material itself, because they allow the brick to
naturally pass water vapor through
the surface of the brick. Be careful about the type of sealant being used on
the chimney, because many types found in hardware stores will simply fill in
all of the natural pores in the brick, trapping water vapor within the
brickwork, without providing a natural escape or evaporation route. If water
vapor is trapped within the brick, it will find the path of least resistance out
of the brick in some fashion, which can lead to cracks and spalling, on the
exterior or interior of the brick. Naturally, this is a con, and should be
avoided.
That said,
there are sealants that are vapor permeable, which coat the exterior brickwork
with a layer of protection from liquids, but still allow the pores of the brick
to “breath”. These sealants provide the maximum amount of protection from
weather conditions, while creating a minimal amount of risk to the underlying
structure of your chimney. If adding an extra layer of protection against
liquids and weather sounds like a good idea for your chimney, a 100% vapor
permeable sealant is the best choice.
To ensure that
the best sealant is applied to your fireplace correctly, and for general
questions about keeping moisture out of your chimney, consult the professionals
at Lindemann Chimney & Fireplace at (847) 739-4199, or you can reach them online!
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