Page 336 - Masonry and Concrete

Masonry Garden Walls

335
MASONRY GARDEN WALLS

for larger projects will probably be damp or wet. The sand should be
kept covered so that the moisture content will not change drastically
because of rain or drying. Within the first two hours after mixing, the
plaster mix can be retempered with water to replace evaporated mois-
ture and restore proper consistency. In hot and dry weather, the time
limits on retempering may need to be shorter. Plaster that has begun to
harden must be discarded.
Before plastering begins, the wall should be moistened by misting
it with a garden hose sprayer and the surface moisture then allowed to
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dry. The scratch coat should be applied and screeded to about a 8-in.
thickness, then scratched to improve bond with the finish coat. Cure
the scratch coat for at least 24 hours before proceeding, but keep the
wall damp by misting with a garden hose. This will assure a strong
surface and minimum shrinkage and is particularly important on hot
or windy days. Plaster that dries out too quickly will have a lot of ran-
dom surface cracks.
The finish coat uses the same ingredient proportions as the scratch
coat. If the scratch coat is dry, moisten it again with a garden hose mist
and let the surface moisture evaporate before beginning the finish coat
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work. Trowel on a finish coat of plaster that is about 8 in. thick, work-
ing up to the edges of the metal control joints, corner beads, and drip
screeds. For a smooth finish, trowel the surface several times as it
becomes progressively harder until you have achieved the texture you
want. Decorative textures can be applied to produce a variety of looks.
Keep the stucco moist for several days while it cures. If the stucco will
be painted, allow about a month for curing first. Choose a porous or
“breathable” type of coating such as acrylic house paint, cement-based
paint, or an acrylic elastomeric coating. Follow the paint or coating
manufacturer’s instructions for cleaning, priming, and painting over
stucco.
To produce a bright white finish coat that will not need paint, sub-
stitute white portland cement and white sand in the mix. This will be
more expensive than painting initially, but the stucco will never need
recoating. To produce colored stucco, add liquid or powder pigments
to the finish coat plaster mix. Measure the amounts carefully and
exactly and make sure each batch of plaster is mixed the same or you
will get uneven coloring. With white portland cement, the colors will
be brighter, but the mix will be more expensive. When using colored

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