Recent innovations in the manufacturing and design of steel studs have produced studs that use less steel yet perform as well and better than traditional smooth-faced studs. This article addresses the challenge architects face when designing and specifying metal stud framing.

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Providing: STEEL STUDS: THRU THICK & THIN
Specifications, Quality Assurance,
Inspections & Investigations Randal J. Reifsnider, AIA, CSI, CCS, LEED AP, SCIP
for your Construction Projects
Dimpled Stud have been tested by a 3rd party in
ABSTRACT: Dilemma accordance with ICC-ES-AC86 and
Recent innovations in the conform to the maximum height
manufacturing and design of steel Recent innovations in the design tables in ASTM C754.
studs have produced studs that and manufacturing of steel studs
use less steel yet perform as well have produced studs that use less Maximum heights are determined
and better than traditional
steel yet perform as well and by stud properties including size,
smooth-faced studs. This article
addresses the challenge architects better than traditional smooth- spacing, metal thickness, yield
face when designing and faced studs. strength, section modulus, and
specifying metal stud framing. moment of inertia. Design criteria
Although these advances are good affecting maximum height include
FILING: for the economy, construction the deflection limit and uniform
UniFormat™ industry, and environment; they load applied to the stud. By code,
C1010 - Interior Partitions have created a problem for the uniform load applied typically
architects and specifiers trying to to interior walls is 5 psf (240 Pa).
MasterFormat™ cope with all the new variables. For elevator and duct shafts the
09 22 16 - Non-Structural Metal uniform load is 10 psf (480 Pa). If
Framing "Dilemma" is the wrong word to the load is more than 10 psf,
describe the situation. "Trilemma" ASTM C645 no longer considers
KEYWORDS: may be more appropriate since the studs to be non-structural.
Metal Studs, Steel Studs, Stud there are now 3 categories of steel
Framing, Interior Framing, studs from which to choose: The values in the Effective
Gypsum Panel Assemblies. Properties portion of Table2 in
 Traditional Smooth ASTM C645 are based on a
REFERENCES:  Dimpled Minimum Yield Stress (Fy) of 33
ASTM C645 - 09a Standard
 High-Performance
ksi. Therefore, these properties
Specification for Nonstructural will not apply to studs composed
Steel Framing Members
ASTM A653/A653M - 09a
ASTM C645 of a higher strength steel.
Standard Specification for Steel ASTM C645 covers cold-formed,
Sheet, Zinc-Coated (Galvanized) or Traditional Smooth
steel framing members for interior
Zinc-Iron Alloy-Coated
construction. This standard, These studs are rolled to form
(Galvannealed) by the Hot-Dip
Process although updated in 2009, does structural shapes with smooth, flat
ASTM C754 - 09a Standard not specifically address dimpled surfaces. They may also have cut
Specification for Installation of and high-performance studs; outs or punch-outs to reduce their
Steel Framing Members to Receive however it does allow for them. weight and to provide for things
Screw-Attached Gypsum Panel like conduit to be run through
Products ASTM C645 requires the minimum them. Traditional studs are
ICC-ES-AC86 Acceptance Criteria coating for all studs to be G40 typically made from 33 ksi steel,
for Cold-Formed Steel Framing according to ASTM A653/A653M but can be made using 50 ksi
Members—Interior Nonload-
Bearing Wall Assemblies and the minimum metal thickness steel. Until a few years ago, these
to be 0.0179 inch (0.455 mm). were the only studs available.
The standard does provide an Now, the construction trend is
exemption for the minimum metal moving away from using
thickness provided the members traditional smooth studs.

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Dimpled
These studs are rolled through
presses with small, alternating
indentations producing a dimpled
surface on the stud. Forming the
surface in this manner reduces the
amount of steel needed to achieve
the same structural capacity of a
traditional smooth stud of the
same overall dimensions. The
dimpled studs are typically made
from 40 ksi steel. To try and help
architects and engineers deal with
the thinner metal, manufacturers
have developed what they call the
Effective Metal Thickness, i.e. the
actual metal thickness may be less
than specified; but because of its
improved design and higher
strength, it will perform as if it is
the same thickness as a typical
stud.
High-Performance
Studs
These studs are made from 50 ksi
to 70 ksi steel and are rolled with Example of Dimpled Stud
a unique form that improves its
structural performance. They are
also made from thin sheets of their studs in slightly different
steel and intended for interior use. forms and may assume slightly  Unbraced walls
different values for variables in the  Sheathing materials other than
Load Tables calculations, table results will vary generic gypsum board, e.g.:
from manufacturer to
All steel stud manufacturers o Wood paneling
manufacturer.
provide load tables. However, care o Cement board
should be taken when using these Tables do not address such things o Impact resistant panels
load tables for design or as:  Point loading for
comparison purposes.
 Multiple and uneven number o Shelving
The load tables are generic in of gypsum board layers. o Cabinets
nature. They cannot take into
 Gypsum board that does not o Grab bars
account the specific and special
go the full height of the o Toilet partitions
conditions of any project. They
framing. o Countertops
can only deal with the simplest
and most common wall conditions.
Because each manufacturer makes

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Specifying Steel for the specific conditions. For and critical stud spacings have
Studs simple wall conditions, the load changed. Of course, when relying
tables may be used. For more on delegated design
The traditional way of specifying
complex wall conditions, a responsibilities for designing the
studs was to provide a minimum
structural engineer and a steel stud framing, the appropriate
base metal thickness that was
stud manufacturer's representative submittals need to be requested
required. In the past, this
should be consulted. which document compliance with
thickness was expressed in terms
the performance requirements.
of a gage. Because gage is not a
Avoid calling out metal
precise measure and varies in
actual thickness from one metal to
thicknesses on the drawings. Additional
Allow an engineer familiar with
another, the system of gages has
framing to determine metal
Information
been replaced by calling for the
thickness and the minimum yield The Steel Stud Manufacturers
actual thickness measured in
stress that are appropriate for Association (SSMA) publishes a
decimals of an inch.
each framing condition. This is a document (ICBO ER-4943P) with
design responsibility that can be useful information and tables
Since there are now a variety of
delegated to the contractor. regarding steel studs. However,
different minimum yield stresses
and deformation patterns used, this document has not been
If stud spacing is uniform updated since 2001 and it only
the actual structural performance
throughout the building, indicate addresses traditional smooth
of steel studs is not governed by
the standard stud spacing in the studs made from 33 ksi and 50 ksi
the base metal thickness alone.
specifications. If there are 2 or steel.
Therefore, base metal thickness is
more different stud spacings used,
no longer an effective way of
indicate each and the extent of Also see "Navigating Non-
specifying steel stud framing.
each on the drawings. structural Metal Framing" by Larry
Specifying that steel studs must Nordin, CSI, CDT, AIA in the
comply with ASTM C645 sets a Submittal Review November 2009 issue of The
minimum standard that allows the Construction Specifier.
If the specifications call out a base
contractor to select the framing
metal thickness assuming a
based on performance, so the
certain ksi value and stud type and
most efficient and cost effective
the contractor submits a different Add Your Comments
framing can be used.
stud type with a higher ksi, the
architect will have a hard time We invite your comments. Visit our
So What Size Stud Do trying to determine whether to blog and add your comments to this
I Need? accept the change. Providing a article's announcement.
performance specification based www.conspectusinc.com/blog
During the DD and CD phase of a on ASTM C645 and project specific
project, stud selection should be loading conditions, makes things
determined based on wall The information contained in this
much easier for the architect to document is offered for educational
thickness desired, span, and handle. The engineer with the purposes, only, and not as technical
loading conditions. It is not delegated design responsibilities advice suitable for any particular
necessary to do a detailed can design the system based on project or specific condition. Technical
engineering analysis at this point. performance, and the architect consulting is unique to the facts of a
It is only necessary to be only needs to review the particular condition, and Conspectus
reasonably sure the wall thickness engineering drawings to make
recommends that a specialist be
indicated is appropriate for the consulted to determine solutions for
sure no critical wall thicknesses
each specific condition.