3.3
JOINT REINFORCEMENT
Reinforce all interior angles and flat joints prior to application of the
veneer plaster. Do not use self-adhering mesh. Reinforcement shall be a
special mesh reinforcing strip embedded in veneer plaster, or gypsum
wallboard joint tape embedded in joint compound.
3.3.1
Mesh Reinforcing
Embed the mesh reinforcing strip in veneer plaster, so that embedment
material is both under and covering the reinforcement. Allow areas of
reinforcement to preset, and leave rough enough for proper bonding of the
plaster coat. Reinforcement shall be set but not dry, before the
application of veneer plaster.
3.3.2
Paper Tape Reinforcing
Press the paper tape into a bedding coat of setting type joint compound,
and immediately cover with a skim coat of the same compound. After the
bedding and skim coats are set, apply a fill coat of joint compound. Set
the reinforcement and dry thoroughly before application of veneer plaster.
3.4
APPLICATION OF GYPSUM VENEER PLASTER
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NOTE: Veneer plaster may be applied to masonry or
concrete surfaces as well as to gypsum base.
Special conditioning and treatment are required for
masonry or concrete surfaces to receive veneer
plaster. Review ASTM C 843 and manufacturer's
literature to determine requirements applicable to
the project, and modify this section accordingly.
Note that any cracking of the substrate will result
in cracking of the plaster.
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Apply gypsum veneer plaster in accordance with ASTM C 843, and with the
manufacturer's approved installation instructions where such instructions
are additional to or more restrictive than the requirements of ASTM C 843.
Apply plaster as a [one-component] [two-component] system. Minimum plaster
thickness shall be as recommended by the manufacturer, but shall in no case
be less than [1.6 mm 1/16 inch for one-component system.] [1.6 mm1/16 inch
for base coat and 0.8 mm 1/32 inch for finish coat of a two-component
system.]
3.4.1
Mixing
Clean mixer between batches to avoid accelerating the setting time. Do not
add other plaster materials to modify the properties of the veneer plaster.
When extreme conditions so demand, small quantities of commercial retarder
or accelerator may be added to the mixing water to adjust setting time.
When used, the retarder or accelerator shall conform to the veneer plaster
manufacturer's recommendations.
3.4.2
Application
Trowel plaster on by hand. Apply with sufficient material and pressure to
develop bond and to provide the specified component thickness.
SECTION 09215
Page 11
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