The FAQs of Standing Seam Panel Clips
These questions and answers provide information about
standing seam panel clips
Structural standing seam panels mate a male
interlock into a female leg creating a clip to ensure a continuous
secure seam along the full length of a metal sheet. These metal
clips secure the panels, and are applied and fastened to the
purlins or building structure. It's a well-known industry
expression, but the truth is: a standing seam roof is only as
reliable as the clips that hold it together. To learn more, what
follows are some of the most important questions and answers that
provide a better understanding of standing seam panel clips.
What are Clips' Benefits?
By using clips, panel installation occurs without penetration
and produces a monolithic, weathertight system. Because they are
concealed, clips help give the appearance of a sleek and
But clips do much more than attach panels and make the roof look
nice. "Standing seam metal roof clips are specifically designed to
interact with their corresponding roof panels to accommodate design
loads, allow movement caused by thermal changes and minimize
deflection due to friction," says Duane Sailors, vice president of
engineering and sales, BPD, a LSI Group company, Logansport, Ind.
"Clips are designed to match the profile of the intended panel to
allow for a nested installation. This nesting allows necessary
movement as well as sealed seams and aesthetic appearance. It is
important to understand the necessary movement is due to thermal
influence: both interior and exterior." "Standing seam metal panel
clips are designed to enable dimensional change of the panel
without fatigue of its fastening, allowing for the thermal cycling
process," says Cindy DeBellis, sales director, SFS Group USA
Inc., Wyomissing, Pa. "They provide durability and protection
from the elements as well as improved aesthetics as they are a
concealed fastening system as opposed to throughfastened
Because standing seam panel clips are concealed, when compared
to through-fastened panel systems, "[They] are not subject to
fastener corrosion, seal deterioration and thermal-induced hole
elongation," says Bobby Marks Jr., staff engineer, Berridge
Manufacturing Co., Houston. "A standing seam panel in many
applications is a permanent roof, wherein a through-fastened panel
system has a limited life cycle."
What Clip Should I Use?
Not all clips are alike. There are one-piece clips and two-piece
clips. "One piece clips are typically only used on our
snap-together profiles," says Jeff Haddock, technical
representative, AEP Span, Fontana, Calif. "One-piece clips are
designed to allow the panel to expand and contract within the clip.
This allows for unlimited thermal movement of the panel while still
securing the panel to the substrate."
Two-piece clips are often referred to as floating clips. These
types of clips are generally used with mechanically seamed
profiles. This is due to the clip being seamed/folded into the
panel's vertical leg. "Seaming it into the panel's vertical leg
prevents the panel from expanding and contracting like a one-piece
clip would allow," Haddock says. "A twopiece clip system includes
the body of the clip and the base. The body is installed onto the
male leg of the panel and the base secured to the substrate. The
female leg of the next panel is installed over the male leg and
seamed into place. This locks the clip into position requiring the
main body and base to move independently of each other."
Small differences in clips can result in major performance
differences. "Having a clear discussion with the designer helps to
resolve any unexpected long-term performance differences," says
Joseph Mellott, vice president, Innovative Metals Co. Inc. (IMETCO), Norcross,
Ga. "An educated discussion with the manufacturer or designer can
reveal a lot about the design and performance differences of
What About Thermal Expansion?
Standing seam steel panels undergo a notable amount of thermal
expansion. Brian Gough, senior engineer, ASC Profiles,
West Sacramento, Calif., says this varies depending on climate,
panel coating, etc., but believes a good rule of thumb is around
1/8-inch of thermal expansion for every 10 feet of panel length.
This means that, "An 80-foot panel will need to accommodate a full
inch of expansion and contraction," he says. "Panel clips are key
to managing this thermal expansion and contraction.
"One-piece clips are designed to slide freely within the panel
seam. Two-piece clips are seamed into the panel hem, and have a
slotted upper- and lower-clip half to accommodate the thermal
expansion. It can vary based on panel design, but in general,
one-piece clips offer unrestricted thermal movement as they can
move freely within panel seam. Two-piece clips on the other hand
have a slotted interface between the two clip halves and have
limitations on maximum t These questions and answers provide
information about standing seam panel clips hermal movement."
What About Clip Spacing?
Haddock says spacing is the most common question he receives
about clips. "Clip spacing can vary drastically based on project
application, substrate, wind speed, uplift pressure and panel
performance to name a few," he says. "Unfortunately, there isn't a
one-size-fits-all spacing. Quality manufacturers should have ample
testing such as UL, FM and ASTM that have tested the panel systems
with specific clip spacing based on substrate application. When in
doubt it's best to use the spacing of a qualified test result."
Mellot agrees that correct wind uplift calculations need to be
performed to establish clip spacing based on panel widths, building
type, and exposure and geographic requirements. "Quality
manufacturers and designers perform wind uplift calculations on
every job," he says.
What About Clip Size?
Manufacturers should have predetermined clip sizes for use with
their roof systems. There are a few factors that determine the clip
size. "For snap seam clips, it is primarily the height of the male
panel leg and to a lesser extent the shape of the panel rib," says
Robert Harris, technical specialist and senior purchaser, Marco
Industries, Tulsa, Okla. "A drawing of the panel [can] be
consulted to verify the clip dimensions needed. For mechanically
seamed panels it is both the height of the panel rib and the width
of the seam. The panel name of the rollformer is usually sufficient
to determine the size requested."
Clip height can range from low profile, where the panel sits
directly on the substrate, up to 1/2- inch or 1-inch taller than
the panel profile. Haddock says using a taller clip creates an air
gap between the substrate and the panel system. This gap can be
used to ventilate the panel and prevent condensation build-up under
the panel system.
What Fastener Goes with the Clip?
Most fastener standards are based on a load test (ASTM E1592,
UL580/1897) that defines panel capacity and sets the fastener
parameters for the panel application. "Knowing the project design
loads and the load capacity of the panel system, defined by a load
test, will direct one to the correct fastening method," Marks says.
"The panel system manufacturer should be able to assist. On
applications with job-specific load calculations, then the engineer
of record designs the fastener size and frequency."
DeBellis says fastener determination for clips is a result of
what substrate (clips, metal) is being clipped and the material
thickness that the fastener is going into. "This would determine if
they need a type A point or a self-drill point," she says. "You
would also need to determine the alloy, i.e., carbon steel or
How Do I Reduce Visible Clip
With some installations, the panels hang from the clips and
there is an air gap between the panel surface and the top of the
clip base and fastener heads. In other assemblies the panels sit
on, or just above the fasteners and clip base. In these
applications the fasteners or clips may show (or read-through) to
the panel surface.
"Quite often, clips in these applications utilize embossments on
either side of the fastener holes to assist in providing an added
bearing surface to reduce chance of fastener read-through," says
Gough. "It is also important for installers to avoid walking on
installed panels near the clip locations to help prevent this from
occurring. Clips with embossments usually have restrictions on
maximum fastener head height. Quite often, these panels require
clip fasteners to be low, pan-head fasteners to reduce chances of
How Do I Install a Clip?
When installing standing seam metal roof clips, it's important
to follow the manufacturer's directions, and use only
manufacturer-supplied or specified components. "Variations in how
the roof is assembled and secured to the building can have
significant implications on its manufacturer warranty as well as
code compliance," says Kevin Hutchings, product training manager,
Manufacturing, Kansas City, Mo.
According to DeBellis, standing seam metal panel clips should be
installed in such a manner that the panel fit with the clip is as
accurate dimensionally as possible to fit over the male leg
component. The female leg must fit securely over the top without
having the fit too snug resulting in objectionably aesthetical
read-through of the clip through the panel (commonly known as panel
transfer). "In the case of a snap-lock profile, there would be no
need for additional seaming," she says. "However, if the panel
profile is a mechanically seamed profile, the use of either a hand
crimper or mechanical seaming device if further required to
complete the seaming process."
Marks says galvanized steel clips are compatible and acceptable
for galvanized or Galvalume metal roof panels. "Aluminum roof
panels require stainless steel clip systems," he adds. "All
fasteners should be zinc coated as a minimum. Some fastener
manufacturers have rust-resistant coatings that can be
Clips are critically important to ensure standing seam metal
roofs function as intended, but they are just one part of the
whole. "It's important to look at each component of the roof as a
system, and even still, it really comes down to modularity,"
Hutchings says. "Always ensure the buildings' structurals are
square and plumb before laying the panels. With a misaligned
building, the clips may not facilitate adequate roof movement.
Proper modularity is imperative for adequate movement and a
weathertight roof. Misaligned modularity can lead to leaks because
the panels stretch and tear when roof movement is hindered."