lead linings placed next to supports.
Blocking shall be provided at end
joints.
3.6.1
Joints
Sheet-lead strips not less than the lead thickness used for wallboard and
not less than 38 mm 1-1/2 inches wide shall be installed on blocking and
supports at all joints.
3.6.2
Corner joints shall consist of 45 x 45 mm 1-3/4 x 1-3/4 inch lead angle.
3.6.3
Wood Supports
The sheet-lead strips shall be secured to blocking and supports at outer
edges with wire nails. Edges of wallboard shall then be butt-jointed and
fastened to supports with lead-headed nails at approximately 200 mm 8 inches
on centers at joints and 300 mm 12 inches on center at intermediate
supports with nail heads driven slightly below the surface of wallboard.
3.6.4
Metal Supports
Edges of gypsum wallboard at metal studs shall be fastened with 25 mm 1 inch
long lead-headed screws. Heads shall be covered with 13 mm 1/2 inch
diameter lead disc cemented to wallboard and installed flush with surface
of wallboard.
3.6.5
Finish Ply
Gypsum wallboard not scheduled to be plastered shall receive a finish ply
of gypsum wallboard bonded to the first ply with laminating adhesive as
recommended by the wallboard manufacturer. Nailing the finish ply will not
be permitted. A shoring system shall be used to hold finish ply in place
during adhesive drying period. Shoring shall be left in place at least 24
hours. Joint and corner treatment shall be as specified in Section 09250
GYPSUM BOARD.
3.7
SUSPENDED LEAD-LINED CEILINGS
Suspended lead-lined ceilings shall consist of lead-lined lath, ceiling
bars, and hangers. Continuous bars shall be spaced approximately [315]
[415] mm [12-1/2] [16-1/2] inches on center and supported by steel hangers
from overhead structure. Lead in the ceiling shall lap lead in the wall by
not less than 38 mm 1-1/2 inches.
3.8
LEAD DOOR THRESHOLDS
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NOTE: Drawings should indicate type of threshold
for each specified radiographic or therapy room.
Thresholds will be included in installations where
floor lining is not installed and if required by
design conditions.
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Thresholds shall be installed in accordance with approved detail drawings.
Prior to installation, lead threshold surfaces in contact with concrete
shall be painted with a coat of asphalt paint or latex material.
SECTION 13090
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