Mastic (Deck O Seal)

Deck-O-Seal (also called mastic) is actually a
brand name of a product that is used in the
swimming pool industry. It is an expansion
joint sealant that is used to seal expansion
joints around swimming pools which are
subject to movement. The product provides a
firm, flexible, water proof seal over the
expansion joint that typically surrounds the
swimming pool—and is typically between the
pool coping and the concrete deck. It is
resistant to swimming pool chemicals. It is
available in three standard colors—tan, gray,
white. Black and redwood (dark brown) are
available on a special order basis.

The expansion joint that surrounds the
swimming pool is a very important interface
between the swimming pool and concrete
deck. Oftentimes there is also an expansion
joint between the concrete deck of the
swimming pool and the house foundation.
These expansion joints are in place so that
these structures can remain independent
from each other when movement occurs. 

The reason that it is necessary to seal the
expansion joint that surrounds the swimming
pool is to keep the water out. Allowing water
to enter the expansion joint area can cause soil
movement (which causes pool or deck
movement) and also the possibility of freeze
damage to the tile, coping and gunite beam. 

Typically every few years the Deck-O-Seal
material becomes dry and sometimes separates
from the coping or the concrete deck due to
movement. This separation allows water to
penetrate, which could cause further
movement or freeze damage to the tile, coping,
and gunite beam.

First the old Deck-O-Seal material must
be removed—even the sides of the
coping and the deck must be free of old
Deck-O-Seal material. Then the expansion
joint must be prepared to receive the
new product—this includes packing the
gap with silica sand. At that point the
Deck-O-Seal material is thoroughly mixed
(it is a two part product) and the new
material is poured into the gap. The cost
of this is $5.50-$6.00 per linear foot. The
complete job can usually be completed
within one day and the product usually
dries within 24 hours in normal conditions.  

Yes you can. We sell the Deck-O-Seal
product and we will be more than happy to
explain the process to you if you decide to
tackle the project yourself. Please be aware
that it is a fairly labor-in-tensive and timeconsuming
project.

Can Deck-O-Seal Be Painted?
No it cannot.

How Do I Clean Up Deck-O-Seal If
I Have Some on My Concrete
Deck or Coping?
If the Deck-O-Seal is still wet, you can remove
it from your concrete deck or coping by using
Toluene or Xylene—use a clean cloth with a
dabbing motion (a circular motion will spread
the product). Please be aware that this might
slightly discolor the deck. If the Deck-O-Seal
has dried, try using fine sandpaper and lightly
sand the area.

Contact us today for all of your Deck needs!