| On this page you will find answers
to many common questions about steel framing. These
FAQs are organized by subject but you may find the
subject you’re interested more quickly by
conducting a simple search. If you use Explorer
as your browser, just press Control and the
“F” key at the same time (Ctrl+F),
then type in the word or words that describe the
subject about which you would like more information.
|
| |
|
|
|
| |
 |
|
General Technical Questions |
|
| |
|
|
Floor Members and Systems |
|
| |
|
|
Wall Members and Systems |
|
| |
|
|
Roof Members and Systems |
|
| |
|
|
Truss and Component Assemblies |
|
| |
|
|
Fasteners and Connectors |
|
| |
|
|
Lateral Systems |
|
| |
|
|
Fire, Acoustic and Thermal |
|
| |
|
|
Cold Formed Steel (CFS)
with other materials |
|
| |
|
|
Corrosion |
|
| |
|
|
Definitions |
|
| |
|
|
Membership |
|
|
General Technical
Questions |
 Back
to top |
| |
|
| |
Question:
Does steel framing product
need to have some approval on them or anyone can
buy the production line and manufacture the studs
and track according to the building codes and materials
of let's say the city of Los Angeles CA? What does
it take to become a manufacturer of steel framing? |
| |
| |
|
Answer:
There is no specific
process for becoming a manufacturer of steel framing,
and there are several levels of manufacturers out
there. At one end of the spectrum are the manufacturers
who have bought a machine, and begin rolling material
from coils or forming material on a brake press.
Some of these manufacturers have no quality control
program, no testing program, and sometimes buy their
coils and sheets without mill certifications or
test reports. On the other end of the spectrum,
members of the Steel Stud Manufacturers Association
(SSMA) are required to maintain an in-house quality
control program, turn in annual audits, and have
all of their material either mill certified or tested.
Also, all material is required to be marked in accordance
with the applicable building code. The marking requirements
are different for different codes, but all require
some form of marking. The
real question is what sort of requirements are
in place in the specific jurisdiction where you
are interested in installing your framing members.
You mention the city of Los Angeles: they require
specific research reports and verification calculations
be submitted, and will issue a research report
such as the one issued to SSMA (http://www.ssma.com/cola_2004.pdf).
Other jurisdictions may require nothing other
than a manufacturer's material certification,
stating that the material complies with code.
The American Iron and Steel Institute has developed
a series of standards that have been adopted into
the building code. The AISI's Standard for Cold-Formed
Steel Framing - General Provisions gives a list
of some of the requirements for framing members:
compliance with specific ASTM standards, manufacturing
tolerances, marking requirements, and corrosion
protection. This is a start. From there, you should
check with the specific jurisdiction to see what
additional requirements are in place before framing
materials may be used in a structure.
Although not a code requirement
in all jurisdictions, I strongly urge you to set
up a quality control program for your incoming
material and manufacture, if you are considering
manufacturing steel framing. Guidelines for this
program are available from the International Code
Council Evaluation Service at http://www.icc-es.org/Criteria/index.cfm.
The Acceptance Criteria that apply to framing
members are AC10 and AC46. Note that the SSMA
does not provide guidelines for setting up framing
operations, and in fact does not admit members
unless they have already been manufacturing and
selling steel framing for at least two years.
There is an association for rollformers that may
be able to give you additional information on
equipment and manufacturing: the Fabricators &
Manufacturers Association, at www.fmanet.org.
|
|
|
Floor Members and Systems |
Back
to top |
| |
|
|
|
|
|
| |
|
|
|
|
|
| |
|
|
|
|
|
|
|
Wall Members and Systems |
Back
to top |
| |
|
| |
Question:
Where can one find additional information regarding
header design? |
| |
|
Answer:
For addition information regarding header design,
additional design information can be found by contacting
the Center for Cold-Formed Steel Structures, ccfss@umr.edu
or the Steel Framing Alliance technical hotline,
1-800-79 STEEL. |
| |
|
| |
Question:
Are there specific provisions in the 2003 IBC for
the anchorage of load bearing exterior and non load
bearing exterior light gage metal walls to the foundation?
What do you recommend? |
| |
|
|
| |
|
Answer:
There are not specific provisions in the
International Code Council's International Building
Code (IBC) for anchorage of cold-formed steel framed
walls; but there are provisions in the International
Residential Code (IRC) for these walls. The IRC
not only has details for this connection, but references
the Standard for Cold-Formed Steel Framing - Prescriptive
Method (AISI 2001) for anchorage, which is typically
anchor bolts through the bottom track at 4' on center.
For non-prescriptive construction, there are several
different methods for wall anchorage that are acceptable
depending upon the load and the seismic zone. The
most common method is powder actuated pins. Companies
like Hilti and ITW Ramset have technical data on
the holding power in structural steel and concrete;
for the bearing in cold-formed steel, use the bolt
bearing equations in chapter E of the North American
Specification for the Design of Cold-Formed Steel
Structures (AISI, 2001). These also may be used
for other anchorage to concrete, such as expansion
bolts, threaded anchors (such as Tapcon and Kwik-Con,)
Spike anchors by Powers Rawl, and others. Recent
developments in epoxy anchors have made them very
popular with cold-formed steel framing; they can
be installed in the exact location required, and
the edge distance and spacing restrictions are less
than the expansion anchors. |
| |
|
| |
Question:
Must an L-header extend over and be attached to
each king stud if there are multiple king studs? |
| |
|
Answer:
No. The Standard for Cold-Formed Steel Framing -
Header Design only requires that the L-header lap
over one bearing stud at each end. |
| |
|
| |
Question:
In certain applications, such as with two adjacent
windows, it is desired to run one header over both
openings. How would such a multi-span header be
designed? |
| |
|
Answer:
The Standard for Cold-Formed Steel Framing - Header
Design applies only to single-span conditions. Multi-span
headers would need to be designed in accordance
with the AISI North American Specification for the
Design of Steel Structural Members. |
| |
|
| |
Question:
How do I calculate the deflection of a header beam? |
| |
|
Answer:
According to the Commentary on the Standard for
Cold-Formed Steel Framing - Header Design, a conservative
estimate of the vertical deflection of back-to-back
or box headers can be based on the full moment of
inertia of the two C-shape sections alone. The procedure
to calculate the vertical deflection of an L-header
is undefined because the L-header is an indeterminate
assembly consisting of two angles, cripple studs,
and track sections interconnected by self-drilling
screws. However, the test results indicate that
the measured deflections at an applied load that
equal to the design load was less than L/240, which
should be acceptable in most applications. |
| |
|
| |
Question:
What load combinations are appropriate for the design
of a header? |
| |
|
Answer:
The Commentary to the Standard for Cold-Formed
Steel Framing - Prescriptive Method for One and
Two Family Dwellings provides a detailed description
of the loads, load combinations and design checks
that are appropriate for headers. The appropriate
load combinations are:
| Gravity |
Uplift |
| 1.4D |
0.9D - 1.6W |
| 1.2D + 1.6L + 0.5(Lr or S) |
1.2D + 0.5(Lr or S) + 0.5L - 1.6W |
| 1.2D + 0.5L + 1.6(Lr or
S) |
1.2D + 1.6(Lr or S) - 0.8W |
|
| |
|
| |
Question:
When assembling a back-to-back or box header, must
the track directly beneath the C-shaped sections
face up or down? |
| |
|
Answer:
The Standard for Cold-Formed Steel Framing - Header
Design allows the track directly beneath the C-shaped
sections to face either way. Typically, the track
would face down when cripple studs and a head track
are used to frame the opening and would face up
when the opening extends to the bottom side of the
header beam and no cripple studs and separate head
track are needed. |
| |
|
| |
Question:
When using steel framing in fire rated wall systems,
is the thickness of the steel the minimum, or the
maximum? I understand that steel transmits heat,
so I thought that the thickness shown might be the
maximum. |
| |
|
Answer:
Each type of header offers certain advantages and
disadvantages; however, the relatively new L-header
offers significant material, fabrication and installation
savings. Due primarily to the limitations of the
testing that has been performed; the Standard for
Cold-Formed Steel Framing - Header Design limits
L-headers to a maximum span of 16 feet. L-headers
also have limited uplift capacity and, therefore,
may not be suitable for certain high wind areas. |
| |
|
| |
Question:
Can the moment capacity of the header beam be based
on a composite section of the C-shape sections plus
the track above the header beam, the track beneath
the header beam, and/or the cripple studs and head
track beneath the header beam? |
| |
|
Answer:
The Standard for Cold-Formed Steel Framing - Header
Design requires a track section above and beneath
the C-shape sections and prescribes their connection
to the C-shape sections with 2 No. 8 screws at 24"
on center. Intentionally, this screw spacing does
not provide adequate restraint to sufficiently engage
the track sections to act compositely with the C-shape
sections. This would require a much closer and cost
prohibitive screw spacing and would need to be designed
in accordance with the AISI North American Specification
for the Design of Steel Structural Members. |
| |
|
| |
Question:
Why doesn't the Standard for Cold-Formed Steel Framing
- Prescriptive Method for One and Two Family Dwellings
seem to require a check for wind uplift on back-to-back
or box headers? |
| |
|
Answer:
Within the applicability limits of the Prescriptive
Method, uplift due to wind was checked and was found
to never control the selection of back-to-back or
box headers. Therefore, the tables only consider
gravity loads. |
| |
|
| |
Question:
Must my header design conform to the design rules
contained in the Standard for Cold-Formed Steel
Framing - Header Design? |
| |
|
Answer:
Yes. The Standard for Cold-Formed Steel Framing
- Header Design has been adopted by reference in
the 2003 ICC and NFPA building codes and thus is
legally required when the local building code adopts
the these building codes. Headers that fall outside
the applicability limits of the limitations of the
Header Design standard must be designed in accordance
with the AISI North American Specification for the
Design of Steel Structural Members. |
| |
|
| |
Question:
When using steel framing in fire rated wall systems,
is the thickness of the steel the minimum, or the
maximum? I understand that steel transmits heat,
so I thought that the thickness shown might be the
maximum. |
| |
|
Answer:
The thickness shown in the UL listings is the minimum.
See the info from the UL website below on cold-formed
steel framing. |
| |
|
| |
Question:
In the UL listings for fire ratings, the thickness
is given in gauge. I know that some of the tests
were done many years ago, and thicknesses and tolerances
may have changed. Are the thicknesses still current? |
| |
|
Answer:
In the UL listings for fire ratings, the thickness
is given in gauge. I know that some of the tests
were done many years ago, and thicknesses and
tolerances may have changed. Are the thicknesses
still current?
| 2. |
Steel Studs |
| |
The dimensions and gauge of steel studs
are minimums. The hourly ratings apply when
the steel studs are of a heavier gauge and/or
larger dimensions than specified in a Design.
The superimposed load of bearings walls
utilizing steel studs shall be based on
the capacity of the studs as determined
by the 1986 edition of the AISI Specification
for the Design of Cold Formed Steel Structural
Members with the December 11, 1989 Addendum. |
| 3. |
Metal Thickness |
| |
Unless otherwise indicated in the
individual designs, the following minimum
metal thickness tables shall apply where
a metal gauge designation is stated. Metal
gauges are no longer referenced in ASTM
Standards. It is still an industry practice
to specify steel components by gauge.
Because many of the designs contained
herein refer to metal gauge the following
information is to be used as a guide where
field questions occur. The tables shown
herein are to be used as a reference and
the local Authority Having Jurisdiction
shall be consulted if discrepancies exist
between these tables and a local code
requirement. Due to structural considerations
and fire performance considerations the
minimum thickness tables are different
for steel deck (floor or roof), load bearing
studs and non-load bearing studs.
The minimum thickness for load bearing
steel studs is based upon ASTM C955-96,
"Load-Bearing (Transverse and Axial) Steel
Studs, Runners (Tracks) and Bracing or
Bridging for Screw Application of Gypsum
Panel Products and Metal Plaster Bases".
The color code denoted by the ASTM Standard
is also shown below. For load bearing
steel studs, the minimum bare metal thickness
shall be as follows:
| Gauge |
Color
Code |
Min
ThknsBare Metal In. |
| 20 |
White |
0.0329 |
| 18 |
Yellow |
0.0428 |
| 16 |
Green |
0.0538 |
| 14 |
Orange |
0.0677 |
For non-load bearing studs, the minimum
thickness is based upon the gauge conversion
table found in the 1997 Uniform Building
Code. For non-load bearing steel studs,
the minimum bare metal thickness shall
be as follows.
| Gauge |
Min ThknsBare Metal In. |
| 25 |
0.018 |
| 24 |
0.021 |
| 22 |
0.027 |
| 20 |
0.033 |
| 18 |
0.044 |
| 16 |
0.055 |
For additional information
on steel-framed wall and floor-ceiling
assemblies, there is a searchable directory
on the Steel Framing Alliance website,
at www.steelframing.org. Also, for additional
information on the details and limitations
of these systems, go to the UL web information
page on these assemblies: |
|
|
| |
|
|
|
|
|
Roof Members and Systems |
Back
to top |
| |
|
|
|
|
|
|
Truss and Component Assemblies |
Back
to top |
| |
|
|
|
|
|
|
Fasteners and Connectors |
Back
to top |
| |
|
|
|
|
|
|
Lateral Systems |
| |
|
|
|
Back
to top |
|
|
Fire, Acoustic and Thermal |
Back
to top |
| |
|
|
|
|
| |
Question:
Can mold grow on steel studs? |
| |
|
Answer:
That's a good question, and one that requires
a little background for the answer.
Mold requires three things to grow:
- The mold spores, which exist everywhere
there is air; every breath we take, unless
we are in a medical clean room, contains thousands
of mold spores.
- Moisture.
- Organic material, which provides the food
for the mold.
Steel does not contain any organic
material, and therefore cannot support mold growth.
However, if someone or something has left a residue
of organic material on the steel framing, there
is a chance that given the right conditions, mold
could grow.
As with any framing material, the
best practice is to keep the steel studs dry.
Even if they get wet during construction, or there
is a one-time event such as a pipe bursting in
a wall, there should be no long-term problem if
the cavity is dried out properly. It is persistent
wetting, such as a steady plumbing or roof leak,
which causes the greatest risk of supporting mold.
Even then, the mold will most likely grow on organic
surfaces, such as the paper facing of the gypsum
board or wood framing members, rather than steel.
In steel framing, when everything is clean and
dry, there will be no opportunity for the mold
to grow.
Note that the Steel Framing Alliance
has an excellent publication on this issue: listed
under the - About Steel Framing - bar on the home
page, go to -Issue Papers - for a free download
of the issue paper on mold. |
| |
|
|
|
|
| |
|
|
|
|
|
|
Cold Formed Steel (CFS) with other
materials |
Back
to top |
| |
|
|
|
|
|
|
Corrosion |
Back
to top |
| |
|
|
|
Question:
Wouldn't enamel coated steel provide better rust
protection for a steel frame home rather than galvanized
steel. |
| |
|
|
Answer:
Enamel painted steel without a galvanized coating
below does not provide a better protection. The
reason is that zinc, through its sacrificial galvanic
action, can "heal" cuts, scratches, and abrasions
in the steel. With the rough handling that construction
products receive, as well as the cutting, drilling,
shearing, and fastening of members, the coating
gets cut and scraped away. The galvanized coating
works better than the enamel at covering areas
that are cut or scratched.
Some of the very best coatings for
steel products are painted over galvanized. The
automotive industry has come a long way over the
past 20 years in providing better coatings, and
this is what they use in several applications.
If for some reason the paint is cut or scratched,
the zinc below the paint can help provide protection,
and reduce the chance of blistering where moisture
gets below the paint surface and rust progresses.
Enamel over galvanized would be
a very effective coating for steel framing. However,
due to the cost, not many manufacturers make such
a product. There are some specialty coil coaters
that will paint material to be rolled into framing
members. As part of the interior exposed drum
wall in the Georgia Dome, studs were galvanized,
painted, and then covered with a thin sheet of
protective plastic before they were rolled into
the "C" shape. As installers put the framing into
place, they removed the plastic. After over 10
years of exposed, in-place service, these studs
(which can be seen from the seating area and playing
field) are still in excellent condition.
Please see "Corrosion
protection for life." |
| |
|
|
|
|
| |
|
|
|
|
| |
|
|
|
|
|
|
Membership |
Back
to top |
| |
|
|
|
|
|
|
Definitions |
Back
to top |
| |
|
|
|
|
| |
|
 |
AISI
American Iron and Steel Institute |
| |
|
|
ASCE
American Society of Civil Engineers |
|
| |
|
|
AWCI
Association of the Wall and Ceiling Industry |
|
| |
|
|
CASE
Council of American Structural Engineers |
|
| |
|
|
CCFSS
Center for Cold-Formed Steel Structures |
|
| |
|
|
COFS
Committee on Framing Standards |
|
| |
|
|
COS
Committee on Specifications |
|
| |
|
|
CSSBI
Canadian Sheet Steel Building Institute |
|
| |
|
|
LGSEA
Light Gauge Steel Engineers Association, a Council
of the Steel Framing Alliance |
| |
|
|
MBMA
Metal Building Manufacturers Association |
|
| |
|
|
MCA
Metal Construction Association |
|
| |
|
|
NAAMM
National Association of Architectural Metal Manufacturers |
|
| |
|
|
NAHB
National Association of Home Builders |
|
| |
|
|
NCSEA
National Council of Structural Engineers Associations |
|
| |
|
|
SFA
Steel Framing Alliance |
|
| |
|
|
SSMA
Steel Stud Manufacturers Association |
|
| |
|
|
STCA
Steel truss and Component Association |
|
| |
|
|
WTCA
Wood Truss and Component Association |
|
| |
|
|
|
|
