3.7
LATHING INSTALLATION
3.7.1
Metal Lath on Vertical Surfaces
Metal lath shall be applied with the long dimension across the supports,
with true even surfaces, and without sags or buckles in accordance with
ASTM C 841. Metal lath on vertical surfaces shall be oriented to provide
maximum mechanical bond with plaster and the upper sheet shall be attached
to overlap the lower sheet. When paper-backed lath is used, the upper
sheet shall be attached to overlap the lower sheet. The lath shall be
secured to supports at intervals not exceeding 150 mm 6 inches. Nails or
staples shall be used for securing lath to wood supports. Tie wires,
rings, clips, or other approved fasteners having equivalent holding power
of the tie wires shall be used for securing the plaster base to metal
supports and to concrete or masonry. Side-laps or junction of sides of
plaster base shall be tied or otherwise secured at intervals not exceeding
225 mm 9 inches between supports, in addition to being secured to supports.
3.7.2
Metal Lath on Ceilings
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NOTE: Unrestrained ceilings and control joints will
be shown on the drawings. Control joints in
plasterwork will be indicated to continue control
joints in structural frame and to divide plastered
areas into not more than 13 square meters (144
square feet) for portland-cement plaster and 230
square meters (2500 square feet) for gypsum.
Interval between joints shall be no more than 4
meters (12 feet) for portland-cement plaster and 15
meters (50 feet) for gypsum plaster. Unrestrained
ceiling design will be mandatory when total ceiling
area exceeds interval limitations outlined above.
Information in brackets not applicable will be
deleted and brackets removed from applicable
information.
Provisions will be included for sealing edges of
unrestrained ceilings in sanitary areas having
medical, dental and food preparation facilities.
Appropriate details from TM 5-805-6, will be shown
on the drawings.
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Metal lath on ceilings shall be in accordance with ASTM C 841. [Lath on
unrestrained ceilings shall not be turned down at junction with wall or
tied to wall lath or furring.] [Lath on restrained ceilings shall be
turned down at junction with wall, or shall be applied to cornerite or
corner bead.]
3.7.3
Side and End Laps
Side and end laps of metal plaster bases shall be performed in accordance
with ASTM C 841 for flat lath and ribbed lath.
3.7.4
Chases and Recesses
Chases and recesses shall be lathed for plastering.
Openings over 300 mm
SECTION 09200A
Page 17
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