the "crown." Wash and cap are two other terms. The way I describe
this part of the chimney to my customers, when talking to them on the
phone, is to "think of a chimney as a shape of a birthday cake. The
layers of the cake are the 'chase', or bricks of the chimney. The
candles are like the flue tiles that stick out of the top of the chimney,
and the crown is like the icing on the cake."
The purpose of the crown is to seal the opening between the edges of
the bricks. It needs to be in good condition to keep water out. Even
though crowns are made of mortar or concrete, they do tend to wear
over the years. Cracks develop from expansion and contraction due to
changes in weather and the use of the chimney. Once a crack starts,
water can enter during the winter, freeze in the crack, and cause
further expansion of the crack. (Remember how powerful ice is? How
about the Grand Canyon?) If you catch the cracks in the early stages,
they can be filled with material that will expand and contract with the
weather while keeping the water out.
There are also various coatings that can be used on the existing crown
surface to waterproof the entire surface of the crown. This can extend
the life of the existing crown for several years.
The way to repair a badly deteriorated crown, would be to remove it
and the wood we almost always find under it, and replace the mortar
with a "floating crown". I describe our floating crown as " a piece of
work that will outlast us, our children, and our grandchildren. We will
rarely install one of our floating crowns if the liners are in poor
condition,or unusable condition. It is much too difficult to remove one of
our crowns in order to replace the liners later.
Call Abbey Road to find out more about our floating crowns.