StuccoMetrics^®

Jeff Bowlsby CCS, CCCA

Exterior Wall and Stucco Consultant

Licensed California Architect

Stucco Lath Accessory Identification

Executive Summary

What is an #X-2 lath accessory? A #25 lath accessory? A #64N lath accessory? When a stucco craftsman refers to these lath accessories or a specifier specifies a lath accessory using these designations, what exactly is being referred to? Is a #7 lath accessory a defined industry standard lath accessory with an engineering drawing and an ASTM-type specification - the same from manufacturer to manufacturer in every respect? How are lath accessory variations designated such as longer flanges, ground dimensions, perforations, material or finish options? Where is the master list of stucco lath accessory numbers or designations for reference? This webpage explores and answers these questions.

Visit the StuccoMetrics Reference Archives webpage for cited references and further information.

Context

Observations

Discussion

The term ‘stucco lath accessory’ is widely used but not defined in the industry. For simplicity, I use the categories of lath, lath fasteners and lath accessory for clarity. ASTM stucco standards refer to stucco lath accessory as ‘accessories’ which is a very broad term used to describe a wide range of lath accessory components with different flange types, functions, installation requirements and more, and these distinctions are not always clearly presented in the ASTM standards. The term ‘stucco lath accessory’ is a better term for the purposes of this discussion and is used here because it is a more appropriate term when used so broadly and it avoids confusion and misinterpretations without getting into the finer points of each accessory and the stated requirements within the ASTM standards for accessories.

Certain sectors of the construction industry, generally by geographic regions or within trades, have become accustomed to using terminology that is not well-defined or universally agreed upon throughout the industry. Terms like ‘Boston ridge’, ‘French drain’, ‘hog valley’ and the like can be confusing or may have multiple meanings. Stucco too has its own language in the form of using certain lath accessory numbers that have come to mean certain things to certain people in the stucco industry. The problem is that the lath accessory number or name referenced by one person may mean something different to someone else because they may have different reference points, experiences or preferences. As an industry, we should seek to eliminate any potential misunderstandings by using a common language and this pertains to how stucco lath accessory items are referenced.

Stucco lath accessories developed over time based on stucco needs and were introduced to the market as early as the 1920’s by companies such as the Milwaukee Corrugating Co. (which became known as Milcor), and each company had their own catalog of stucco lath accessory products they brought to market. The first stucco lath accessory widely available was the corner bead such as produced by Milcor, so that lath accessory item became known as the #1 in their catalog and ultimately became a standard way of referencing this lath accessory component in the trade. As the various manufacturers catalogs grew, more lath accessories were added and more numbers. Each manufacturer used their own method of naming and numbering their products, sometimes using the common industry descriptors of well-established products such as ‘#1”, and sometimes using a different numbering or naming system. So a #X lath accessory by one manufacturer, could be different than a #X by another manufacturer, and in fact that is exactly what has happened.

A generic master coordinated stucco lath accessory designation list universal to all manufacturers, with engineering drawings or ASTM-style product standard for stucco lath accessories does not exist. Lath accessory designations as used today and in the past can be a number, a name, a number and name, or an alpha-numeric designation and vary widely between manufacturers with only limited consistency. Stucco trade traditions for the general descriptions of certain lath accessories by number or name have passed down through the generations, but this practice should be used with great caution because of the limited consistency throughout the industry. Consideration should be given to abandon this practice and replacing it with a universal lath accessory designation system. On a jobsite, craftsman casually referring to lath accessories by number is common trade practice and may not cause any heartburn, but for an Architect or specifier to use and rely on that same casual nomenclature in details or specifications is imprecise and does not communicate exact requirements.

Stucco lath accessory number designations are utilized in different ways by different manufacturers. Most commonly a manufacturer assigns a lath accessory number to a basic sectional profile configuration (e.g. Nos. 1, 7, 66), loosely based on tradition. Other times, a manufacturer will use a lath accessory number to designate size (e.g. Nos. 38, 50, 75, 100 Zinc Control Joint by Clark Western, or the Nos. 120, 140 by Superior). Making things more interesting, manufacturer’s today modify those base numbers with prefixes and suffixes to further describe and distinguish their product from competitors. An X-__ can be expanded flange, where an __–N can be a nailing flange, etc.

Stucco lath accessories may and often do serve multiple functions. Similar but different stucco lath accessories may have the same number designation but have different installation requirements or function differently. For example, a casing bead lath accessory terminates the stucco mortar, and its ground functions as stucco thickness gauge and provides a surface to seal to an adjacent window or door. If the casing bead lath accessory has an XSM flange, it is appropriate and performs best to install it over lath, wire-tied to the lath edge, allowing the stucco mortar to key the lath accessory with the lath, so that when the stucco shrinks the casing bead goes with it preventing a gap between the stucco and casing bead lath accessory. If the casing bead has a solid flange, it is required to install it under the lath, fastened to the framing. When the stucco shrinks a small gap may occur between the casing bead lath accessory and the edge of stucco with solid flange lath accessories fastened to the framing.

Lath accessories with differences in flange types – solid or XSM – should be installed differently. XSM flanged lath accessories if screwed or nailed in place over a WRB, can damage the WRB and cause water intrusion, and so are best wire tied over lath. Solid flanged lath accessories are best placed directly over the WRB and fastened to framing.

A major point of this website is that the common practice of designating lath accessories by a traditional number or name has diluted the understanding in the industry of the distinction between simply identifying a lath accessory component and the functional and performance characteristics of the assembly the lath accessory component helps create. In other words, by itself a corner bead lath accessory is not an arris assembly, it is one component in a configuration of several components, including the framing, WRB, lath, lath fasteners, corner bead lath accessory, lath accessory fasteners, stucco mortar that fills and surrounds the corner bead lath accessory, and the stucco finish coat, that each contribute to making an arris assembly. Similarly, all by themselves, a control joint lath accessory is not a control joint assembly and a weep screed lath accessory is not a drainage assembly, without considering the other related components in the assembly.

It is more clear and correct when referencing stucco lath accessory items to reference them using a complete manufacturer name and catalog number. To be complete and accurate, a lath accessory specification requires the lath accessory manufacturer name and complete lath accessory description including material, critical dimensions and variations specified that are available by that manufacturer to minimize errors when designing, specifying, ordering, purchasing and installing stucco lath accessories. This website avoids the designation of stucco lath accessories by number, name or alpha-numeric designation to avoid any misunderstanding.

A new replacement standard lath accessory referencing convention is needed that is universal among lath accessory manufacturers that will more accurately describe lath accessories and reference associated installation requirements and reduce misunderstandings.

Best Practice: The current practice of referencing lath accessories only by number, name or alpha numeric designation is flawed and obsolete and should be abandoned because no standard universal comprehensive lath accessory designation system exists.

Further Research: This would help to promote communication, prevent inconsistencies and errors in the industry. Consider categorizing assemblies and lath accessories suggesting the function of the assembly, as a possible preliminary designation using the 2-4 letter acronym lath accessory categories I have used in the index.

References

· Cemco catalog, 2009

· Clark Western catalog, 2006

· Milcor Manual, 1924

· Milcor Partition Handbook, 1940

· Milcor catalog, 1960

· Stockton catalog, 2004, 2005

· Superior catalog, 1977, 2001, 2004

· PennMetal catalog, 1959

· Western Metal Lath catalog, 2005

Conclusions

Suggestions

Consultation with licensed and experienced stucco professionals is recommended for stucco-related endeavors. No liability is accepted for any reason or circumstance, specifically including personal or professional negligence, consequential damages or third party claims, based on any legal theory, from the use, misuse or reliance upon information presented or in any way connected with StuccoMetrics.com.

Lath Accessory Identification
Photos – Right click on photos for larger image	Mfr. Lath Accessory Code	Proposed Lath Accessory Code	Description
Photos – Right click on photos for larger image	Mfr. Lath Accessory Code	Proposed Lath Accessory Code	Description	Catalog Source
	1		Expansion corner bead for outer angle	1924 Milcor
	1		Expansion Corner Bead-Small Nose	1960 Milcor
	1		Base Ground and Screed	1977 Superior
	2		Expansion Corner Bead Inner Angles	1924 Milcor
	2		Casing Clip	1940 Milcor Partition Handbook
	2		Artisan Wing, Arch Bead	1959 PennMetal
	2		Base Ground Screed	1977 Superior
	2		Drip	2004 Stockton
	2		Narrow V Screed	2004 Stockton
	2		Small V Screed	2004 Superior
	3		Expansion Flush Base Screed	1924 Milcor
	3-X		Standard Expansion Flange Base Screed	1959 PennMetal
	3		Expansion Flush Base Screed	1960 Milcor
	3		Flashing Screed	2009 Cemco
	4		Quarter Round	1924 Milcor
	4		Casing Bead Quarter Round XSM flange	1940 Milcor Partition Manual
	4		Casing Bead Quarter Round XSM Flange	1960 Milcor
	4		Expansion Casing Bead	1960 Milcor
	4		Short Flange Corner Bead	2005 Western Metal Lath
	4X		Quarter Round Expansion Flange	1959 PennMetal
	5		Drip	2005 Stockton
	5		Soffit Corner Drip Mould	2004 Superior
	5		Standard Bullnose Bead	1959 PennMetal
	6		Drip Head	2009 Cemco
	6		OG Casing Bead OG XSM Flange	1940 Milcor Partition Manual
	6		OG Expansion Casing	1924 Milcor
	7		Bullnose Expansion Corner Bead	1960 Milcor
	7		Expansion Flashing	1924 Milcor
	7		Foundation Sill Screed	2006 Clark Western
	7		Weep Screed	2001 Superior
	7		Weep Screed	2004 Superior
	8		Bullnose Expansion Corner Bead	1960 Milcor
	8		OG 24 Gauge	1924 Milcor
	8X		Expanded Flange Bullnose Bead	1959 PennMetal
	9		Casing Bead Quarter Round XSM FLange	1940 Milcor Partition Manual
	9		Transition Control Joint	2009 Cemco
	10		Blind Stop Drip Mould	2004 Superior
	10		Bullnose Expansion Corner Bead	1960 Milcor
	10		Casing Short Flange	1960 Bostwick
	10-X		Expanded Flange Bullnose Bead	1959 PennMetal
	11
	12
	12
	12
	15

	15
	15
	15
	15
	15
	15
	15
	15

	16
	16
	16
	17

	17
	17
	17

	18
	20
	20
	24
	25
	30
	30
	30
	32
	33
	36
	38
	38
	40
	40
	40
	40
	50
	50
	50
	60

	60
	60
	60
	60
	60

	66
	66
	66
	66
	66
	66
	66
	66
	66

	70
	70
	73
	74
	75
	75
	77
	77
	90
	100
	115
	115
	120

	120
	120

	138
	138
	140

	140
	140

	222
	222
	224
	224
	235
	501
	701
	704
	705
	745

	A-4
	A-5
	A-6
	A-7
	A-8
	A-9
	A-12

	Arch Bead
	Casing Bead
	Casing Expanded Flange – Square Flange
	Double J Expansion Control Joint
	Expanded Base Bead
	Foundation Weep Screed

	J-1
	J-1
	J-2
	J-2
	J-3
	J-4-U
	J-5-7
	J-5-7
	J-6
	J-8
	J-8
	J-11
	J-11
	J-12
	J-13
	N-4
	N-60
	N-66
	N-66
	Rigid Bead-Small Nose Corner Bead
	SST
	Super-Ex-Small Nose Corner Bead
	X-1

	X-1
	X-1

	X-2
	X-3
	X-4
	X-10
	X-20
	X-60
	X-66
	X-66
	XJ15
	XJ-15-3

Consultation with licensed and experienced stucco professionals is recommended for stucco-related endeavors. No liability is accepted for any reason or circumstance, specifically including personal or professional negligence and consequential damages, based on any legal theory, from the use, misuse or reliance upon information presented or in any way connected with StuccoMetrics.com.

Home Page Contact Me Disclaimer