ASTM C 1063-08 Metal Lath Installation Guide
- June 12, 2024
- ASTM
Table of Contents
ASTM C 1063-08 Metal Lath Installation Guide
How to Install Metal Lath
These installation recommendations are intended to be instructional and accurate. This is first a guideline, providing a general overview and also equips the lather with specific installation details, based on ASTM C 1063-08 Standard Specification for Installation of Metal Lath. Always consult your area building official before beginning any project to familiarize yourself with any local code requirements. This guide should not replace the designs and judgments of a qualified engineer and/or architect.
Lath Installation
Begin at the right-hand bottom corner of the wall. If paper backing behind the lath is required, leave the paper overhanging at the top and to the left of the sheet. Offset paper backing has the paper overlap-ping 1-1/2” on one end and one side and corresponding retracted on the opposite end and side, the sheets should always be installed in a horizontal application perpendicular to the framing. Laps: Minimum of 1” at edges with ends nested paper to paper, metal to metal. Apply the second sheet to the left of the first sheet lapping paper over paper and lath over lath. Place the third sheet centered above the first two sheets. This process is similar to that of laying bricks. This staggers the vertical butt joint seams and allows a more uniform dispersal of stress.
Nailing Methods
On horizontal applications, all nails shall be driven flush with base. On vertical applications, nails shall be bent over to engage at least 3 strands over and through rib on rib lath and bridge ribs with staples.
Lath Fasteners (per ASTM C-1063)
- Concrete/CMU: use (3/8” diameter shank, 3/4” minimum length).
- 6 power or powder actuated fasteners, 4 in the corners and 2 in the middle of the long edge.
- Wood framing: use 11 gauge 1-1/2” length, 7/16” head nails (roofing nails 4d 1-1/2” x1/4 head)
- Sheathing on wood framing: use 14 gauge, 1-1/2” leg, 3/4” crown staples
- Metal framing: use self-drilling, self-tapping #12 x 3/4” wafer head screws. Use of powder-actuated or power-actuated fasteners is acceptable, but may cause spalling when shot to the substrate; follow the manufacturer’s instructions carefully.
- ICF: Consult specific ICF manufacturer.
Fastener Spacing
The spacing of nails, staples, or screws is not more than 7” on the center
along the framing member (horizontal or vertical).
Concrete: 6 power-actuated fasteners, 4 in corners, 1 on each side of the
long edge in the center.
Span Limitations
Every finish material is subject to span limitations, which is the maximum
distance between frame members. When sheathing is not required, 16” on center
is the maximum spacing of framing to prevent undue sagging. Then a minimum
2.5# self-furring lath is installed over a sheathing or solid surface, and the
maximum spacing of supports maybe 24” on center.
Note: Lath shall be furred away from vertical supports or solid surfaces
at least ¼”. Self-furring lath “dimples” “V-grooved” or “ribbed” lath meets
these furring requirements. See chart “Support Spacing for Metal Lath” on page
3 (bottom) of this catalog.
Cut and Trim to Fit
Standard sheet shears or metal cutting scissors are effectively used for
notching and snipping. A conventional circular saw equipped with a metal
cutting blade easily zips through steel lath to cut to desired lengths.
Wire Tie (0.0475”, 18-gauge)
Lath is to be wire tied at 9” on center at edges, ends, and at laps between
framing members. On plywood sheathing only, lath may be nailed or stapled in
lieu of tying at the same center spacing noted above.
Accessories
Corner beads shall be used to protect all external corners with a plumb and true edge. Casing beads shall be used to terminate stucco or stone around doors, windows, or other openings. Flashing shall be used where lath and stucco are to be applied on walls.
The intersection of the roof plane
(i.e.: bulkheads, sidewalls, headwalls), a stucco stop, flashing/ counter
flashing shall be carried over the flashing to terminate the stucco and/or
stone. AMICO recommends zinc alloy or vinyl for exterior applications.
Important Installation
Note
Lath accessories are designed to make plaster jobs easier, more effi-client,
and provide the final product a more professional look. To ensure this,
accessories should be attached every 18” with nails, staples, or tie wires.
For control joint, corner, and casing beads, the nose can be used as a screed
for the stucco brown coat but must be embedded by 1/8 inch thickness of
plaster on the final coat.
Jointing for Cracking Control
It is difficult to anticipate or prevent plaster cracks, but they can be
largely controlled by means of expansion joints. The expansion joints should
be installed between laths. The lath is to be broken underneath the expansion
joint to function properly. Fasten the joints to the lath using the info found
under the “Lath Fasteners” section. Walls and ceilings that use metal lath for
the plaster base should be divided into rectangular panels with control joints
at least every 18 feet or at the juncture of a dissimilar wall, or in either
direction in a length-to-width ratio of 2½ to or in ceilings exceeding 100 sq.
ft. or walls exceeding 144 feet in area. Control Joints shall be formed by
installing a single-piece Griplock J™ or #15 VV-Type accessory. Install the
M-SlideTM 2-piece expansion joint where an expansion joint occurs in the base
exterior wall, or dissimilar substrates align next to each other. M-Slide
Vertical is for vertical applications and M-Slide Horizontal is for horizontal
applications used within floor-to-floor framing, etc.
Installation Detail Photos
Attachment of Lath to studs
- Wafer head screws are power-driven to allow quick and easy attachment of Diamond Mesh Lath to frame members.
- Diamond Mesh Lath can be cut to size with hand tools.
Attachment to solid surfaces
- Self-Furred Diamond Mesh Lath is secured to masonry surfaces with hardened concrete nails and power-driven fasteners at the furring dimples. Paper-backed lath is often used in this type of application as a bond breaker.
- The scratch coat is applied with the complete embedment of the self-furred lath in the plaster.
- The scratch coat is fully embedded in the lath and is isolated from the supporting structure. Water-resistant backing paper allows controlled and uniform curing of this plaster foundation.
Attachment of Rib Lath to ceilings
High (3/8”) Rib Lath is attached to a ceiling joist, spaced at 24” o/c max.
Flat Rib Lath can span up to 16” o/c.
Attachment of trims/joints
- Type “M” Expansion Joint is installed vertically over the window opening allowing for expansion and contraction.
- AMICO X-1 Corner Bead provides protection for outside corners and a reliable straight ground for screeding.
- X-66 Expanded Casing Bead is typically installed at door and window openings as a plaster stop.
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