Galvanizing Lath – Standards & Specifications

Issued: June 2015




Corrosion protection of metals including lathing for  cement  plaster  (stucco)  is  governed  by  building codes. Corrosion protection is prescribed as galvanization.

The  following  outlines  the  standards  and requirements for galvanization that are now in effect in the US states that have adopted the IBC and IRC codes: 

In Table 2507.2 titled “Lath, Plastering Materials and Accessories”, the International Building Code (IBC) cites ASTM C847 – Metal Lath; ASTM C933 – Welded Wire lath; and ASTM C1032 – Woven wire plaster base. In Table 2511.1 titled “Installation of Plaster Construction”, the IBC cites ASTM C1063 – Lathing and furring (cement plaster)

Similarly, the International Residence Code (IRC) cites the same ASTM standards in section R702.2.2 – Cement plaster.

In C1063 in paragraph 6.4, the requirement for wire is ‘Wire – as specified in Specification A641, with a Class 1 zinc-coated (galvanized), soft-temper steel.’

ASTM standard A641 is “Standard Specification for Zinc-Coated (Galvanized) Carbon Steel Wire”. In the standard, the various minimum zinc coating requirements are given for Class 1 coatings by wire size.

In C1063 in paragraph 6.2.3, the requirements for sheet steel items is : ‘Steel – Specification A653 and shall have a G60 coating’.

Standard A653 is a specification for steel sheet, zinc coated (galvanized) or zinc-iron alloy-coated (galv-annealed) by the hot-dip process.

Further in C847 for metal lath in paragraph 3.1, the requirement is ‘Galvanized metal lath shall have a G60 coating in accordance with Specification A653′.



Specifications for stucco reinforcing lath are as follows:

Lath Type: Welded & Woven Wire

Zinc Coating Requirement: ASTM Class 1


Lath Type: Expanded Metal

Zinc Coating Requirement: G60


The building code specification recognizes that the principal long-term condition for corrosion protection is achieved by full stucco embedment of the stucco metal base.

The distinct embedment characteristics of wire lath and expanded metal reflect the differential zinc coating weight requirements.


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