ceilings abutting plastered surfaces. At the perimeter of unrestrained
suspended ceilings, the casing bead shall be secured to the ceiling to
provide a 10 mm 3/8 inch opening between the abutting surfaces. The
opening shall be sealed prior to plastering with sealant as specified in
Section 07920 JOINT SEALANTS.
3.10.5
Expansion and Control Joint Beads
Expansion joint beads shall be installed as control joints in plasterwork
at the locations indicated. Plaster base shall not be run continuous
through control joints. Additional supports shall be installed as required
to support the beads.
3.10.6
Trim
Trim shall be installed where indicated and as required to complete the
plaster work.
3.11
PLASTER THICKNESS AND SURFACE EVENNESS
Plaster thickness and surface evenness shall be controlled by grounds or
screeds of metal, wood, or plaster. Wood grounds are specified under
Section 06100A ROUGH CARPENTRY. Plaster thickness shall be as shown.
3.11.1
Grounds and Screeds
Grounds shall be used for securing trim items, and for finished corners and
terminations. Screeds shall be installed for base screeds when wood or
metal grounds are not required. Temporary screeds shall be installed when
permanent screeds or grounds cannot be used. On completion of approved
base coats, temporary screeds shall be removed and voids immediately filled
with plaster.
3.11.2
Plaster Screeds
Plaster screeds shall be used within the plastered areas to supplement wood
and metal grounds and screeds.
3.12
PLASTER GROUT
Plaster grout shall be scratch-coat material mixed to a non-fluid
consistency. Plaster grout shall be used to fill steel door frames and
partition bases. Grout shall be placed and grooved prior to gypsum lathing
operations. Heads and jambs of frames shall be filled solid with grout,
and 13 mm 1/2 inch deep grooves shall be formed in the grout, while
plastic, to receive gypsum lath.
3.13
3.13.1
Portland Cement Plaster Base Coat
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NOTE: Select base coat L or C from table 2 of ASTM
C 926. Specify base coat L for general use and for
aesthetic finish, and base coat C for optimum impact
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Base coat shall be proportioned and mixed in accordance with ASTM C 926
SECTION 09200A
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