alternate courses.] [Wall joints shall not coincide with the ceiling
joints.] [Each sheet shall overlap the lead extension on the adjacent
sheet, providing an effective lead lap.] [Lead-lined lath shall be applied
with long edges parallel to supports and with lead linings placed next to
supports. Blocking shall be provided at end joints. Sheet-lead strips,
not less than the lath thickness and not less than 40 mm 1-1/2 inches wide,
shall be applied on blocking and on supports at joints. Lead strips shall
be secured to blocking and supports at outer edges of strips.] Lath shall
be close fitted and uniformly secured to supports. Approximately 6 mm 1/4
inch shall be allowed between horizontal joint to form key for plaster.
3.5.2
Frames and Corners
Lath shall extend into frames of openings effectively lapping with lead
frames or frame linings. Unless otherwise approved, lath shall be arranged
around openings such that neither horizontal nor vertical joints occur at
corners of openings. External corners shall be reinforced with corner
bead. Internal corners, except at unrestrained suspended ceilings, shall
be reinforced as required and shall be installed with lead-headed nails or
tie wires and lead tabs. At unrestrained ceilings, square-nosed casing
beads shall be installed at the junction of walls and suspended ceilings.
3.5.3
Wood Supports
Lath shall be uniformly nailed to wood supports at approximately 175 mm 7
inches on centers with lead-headed nails. Nail heads shall be flush with
lath surface.
3.5.4
Metal Supports
Lath shall be uniformly secured to [wood furring strips which are secured
at right angles to the metal supports with bolts or screws. Lath shall be
secured with lead-headed nails with the nail heads flush with lath surface]
[metal supports with 25 mm 1 inch screws or tie wire and lead tabs folded
over the fasteners].
3.6
LEAD-LINED GYPSUM WALLBOARD
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NOTE: A nonlead-lined finish ply of gypsum
wallboard may be installed where required by design
requirements. Style 1, butt-joints, will be used
for the base ply of two-ply construction. The
finish ply shall be bonded to the first ply with
laminating adhesive applied as recommended by the
manufacturer of the wallboard. A shoring system
shall be used to hold the finish ply in place during
the adhesive drying period. Shoring shall be left
in place at least 24 hours. Nailing of the finish
ply will not be permitted. Joint and corner
treatment shall be as specified in Section 09250
GYPSUM BOARD.
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Lead-lined gypsum wallboard shall be applied over supports specified in
Section 06100A ROUGH CARPENTRY and Section 09200A LATHING AND PLASTERING.
Method of predrilling or drilling pilot holes shall not cause deformation
of the fastener and shall not cause distortion of wallboard. Wallboard
shall be applied vertically, with long edges parallel to supports, and with
SECTION 13090
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