The myth I am trying to bust is that old
lime and sand plaster is
not gypsum plaster which is super
I worked for years on hospitals, schools, jails,
government buildings, etc.
which required durable walls for resistance
to abuse. In applications like hospitals,
cheap drywall is pound foolish. The
basecoat plaster we used was "hardwall"
or gypsum plaster
and sand. Lightweight aggregate
such as perlite and vermiculite
wasn't permitted because it is too weak.
The basecoat plaster you see at Home Cheapo (structolite
or gypsolite) is gypsum plaster with
perlite premixed, just add water and
This is for convenience for Handy Andy and Harry
Homeowner, but is too weak to be used on
commercial work. The instructions on the bag
even say it is not to be used on metal lath.
I didn't even mention that hardwall and sand is
four times cheaper than pre-mixed plaster.
On most lime and sand stucco
houses we work on
the sheathing and framing
lumber is still in
good condition AFTER SITTING WITH
GAPING HOLES FOR YEARS.
is good shape on this 1920 wood lath
and lime and stucco house that
had fallen into
disrepair over the years.
EVEN THE WOOD LATH WAS IN GOOD
Note how our forefathers wrapped
the window openings with
homemade tarpaper, and left a
gap between each sheathing board.
Lime and sand plaster almost always was
reinforced with hair. This is referred to mostly
horse hair plaster. Another Mythbuster:
Hair used in lime and sand plaster was mostly
cow hair and even human hair,.
A couple of generations ago, back in rural
America, animals were shaved
to prepare the skin for making leather. Farmers
would accumulate this hair and sell it in the
market for use in lime plaster. Human hair from
barber shops was also used. Hair was sold for
in Richmond, Virginia up until the early 1950's.
Mel Gibson's great movie, Apocalypto,
showed the Mayan Indians making lime, and
with lime plaster.
The Mayan method was inefficient. Limestone
rocks were piled on firewood and heated, instead
being heated in a lime kiln. This
explains the mass deforestation in the Mayan
empire. The trees were
used for making lime. The Mayans had an advanced
construction industry, as shown by their
The ancient Romans discovered that by
adding volcanic ash, or pozzolan, or
brick dust, dramatically
increased the strength and water resistance of lime
stucco and lime cement. The
testimony for this
is the buildings and aqueducts that are still
there. I went to an art exhibit at the National
Gallery of Art
showing the art of Pompeii, and I was amazed
that stucco frescoes were still in good
that had been under water and and
volcanic ash since 79 AD.
Ancient people in India and Egypt also
discovered and used lime.
Even though Portland cement was invented in the
1820's, it wasn't used much in stucco until
the 1890's. Lime and sand was mostly used in
stucco until about 1930, when almost all
was Portland cement. Speaking from my own
observation, I have only worked on
5 buildings built between 1890 and 1930 that had
cement stucco. Everything else is lime and sand.
I have yet to work on a building built after
1930 that was lime and sand, all I have seen
From the job:
I took this picture at the job yesterday.
This shows an observation that I have
made. Note how the
1921 sheathing is still in good
condition. Usually when we tear off lime and
sand stucco, the sheathing and framing are
in like new condition. Please note how
our forefathers left a gap between the
to allow for building movement.
| Another observation from
Even though the metal lath isn't galvanized,
signs of corrosion but not bad deterioration.
Not bad after 90+ years.
This is due to the thickness, an honest 3/4".
When we find failure due to badly deteriorated
the stucco was put on way too thin.
BTW: If you are wondering why the wall failed,
the original copper flashing was put on backwards,
that is angled back to the wall, instead of away from
the wall. The water infiltration after 90 years caused
the stucco to delaminate. Please read what I have to say
about backwards flashing here and here.
Another Mythbuster: Ostriches don't stick their
heads in the sand when they are scared.
The just run away like any other animal.