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What is Hard-Coat
Stucco?
History
As far back as civilizations existed, traces of
plastering appear. From the oldest known civilization (Sumerian, ~
4,000 years B.C.) who built the first known city - Uruk (top
left) - to the Egyptians Pyramids (~ 2,500 years B.C.), mixtures
of different minerals resulting in some form of plaster were
found. In earlier times, limestone was the main ingredient but as
time passed and technology improved, Portland cement became the
ingredient of choice.
As seen on the photos, exterior plaster is still present
on these pyramids, standing thousands of years of weathering from the
beaming desert sun, torrid temperatures and freezing nights
From ~ 800 to ~ 400 B.C., Greek and Roman civilizations
continued to improve the use of limestone for wall plastering.
However, Plaster saw a sharp decline in interest during the Middle Ages
(~1200 to ~1500 A.D.).
It was not until the ~1600 that the interest for
plastering/cement resurfaced. And in 1779, Bry Higgins was issued
a patent for hydraulic cement (stucco) for exterior plastering
use. Then, in 1810, Edgar Dobbs received a patent for hydraulic
mortars, stucco, and plaster; although they were of poor quality due to
lack of kiln precautions.
Subsequently, in 1824, Joseph Aspdin of England invented
Portland cement by burning finely ground chalk with finely divided clay
in a lime kiln until carbon dioxide was driven off. The sintered product
was then ground and he called it Portland cement named after the high
quality building stones quarried at Portland, England.
Stucco has stood the test of time through thousand of
years. Through research and development, Sider-Oxydro
is committed to continue to improve our products to stand against modern
day environmental factors to last for years to come.
The application of Hard-Coat Stucco:
Past & Present
Hard-coat
stucco is applied either by hand or machine to exterior and interior
wall surfaces in two or three coats. It may be applied directly to a
solid base such as masonry or concrete walls, or it can be applied to a
metal lath attached to frame construction, solid masonry, or concrete
construction. Applied directly to concrete masonry, hard-coat stucco
provides a tough finish that is integrally bonded with the masonry
substrate. When applied to metal lath, two to three coats of stucco are
applied. A vapor-permeable, water-resistant building paper
separates the plaster and lath from water sensitive sheathing or
framing. Hard-coat stucco has high impact resistance, sheds water but
breaths, allowing water vapor to escape. It is a proven system that
works in all climates.

Today, Sider-Oxydro
has taken traditional stucco steps further. We now manufacture
premixed, integrally-colored stucco's and decorative coatings, only
requiring the addition of water at the site. This process insures
a high quality product from every bag and eliminates the labor
intensive addition of masonry sand to the cement. More importantly,
due to our latest state-of-the art automated manufacturing process, it insures an
excellent color consistency, eliminating the addition of color packets on the
job.
As technology improves, new
forms of substrates are developed such as AAC (Autoclaved Aerated
Concrete), ICF (Insulated Concrete Forms) and many more for which
Sider-Oxydro
manufactures
a complete line of specially formulated products.
As well, our
hard-coat stucco's no longer contain just cement, lime and sand.
Through research and development, they are formulated with many
different additives to render exceptional properties such as increased
hardness, better flexibility to prevent cracking, water resistance yet
remaining vapor permeable, better color retention, better workability
and many more!
The final
appearance of the finish coat can be varied by utilizing different techniques
of application by the plasterer's skill in manipulating the finish
and/or using different application tools and equipment.

Hard-Coat Stucco vs. EIFS
(Synthetic Stucco)
Portland cement
plaster (sometimes called traditional stucco) should not be confused
with the Exterior Insulation and Finish System (EIFS) or synthetic
stucco systems that have become popular but more recently have been the
subject of controversy as a result of performance problems, including
water leakage and low impact resistance.
Exterior
Insulation & Finish System is a system composed of several layers
installed directly over exterior sheathing such as plywood. EIFS
consists 1/8” layers of acrylic applied over an insulation board such
as polystyrene.

Traditional
Portland cement plaster (hard-coat stucco) is a time-tested exterior
breathable finish. It consists of Portland cement and sand mixed with water to form a workable plaster. Portland cement, the same
material that is the basis for the hardened properties of concrete used
to build super-highways, bridges, and skyscrapers provides strength,
durability, and toughness in Portland cement plaster.
While the
acrylic coatings repel water very effectively, problems arise when
moisture gets behind the synthetic stucco and is trapped inside the
wall. Trapped moisture eventually rots insulation, sheathing, and wood
framing. It also corrodes metal framing and metal attachments. There
have been fewer problems with EIFS used over solid bases such as
concrete or masonry because these substrates are very stable and are not
subject to rot or corrosion.
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