Suspension System Terms
Access Hook – Used in concealed tee system to support a row of tile to be installed in a 4' x 4' module that also allows access to the
plenum above. Also called Saddle Spline.
Breather Spline – Spline used to link tiles in a concealed tee installation and to prevent air infiltration.
Bulb – The upper ridge of the main runner or cross tee with a rectangular, triangular or round configuration. Adds structural
load strength to the component.
Cap – The rolled covering on the flange of a T-Bar. T-Bars come with an aluminum or steel cap and in many colors.
Ceiling Suspension System – A system of metal members, designed to support a suspended ceiling, typically an acoustical ceiling. Also may be designed
to accommodate lighting fixtures or air diffusers.
Clips – Several clip designs are available to suit applications such as fire resistance, wind uplift and impact. Fire-resistance
rated designs have exact requirements, including the mandatory use of hold down clips for acoustical panels or tiles weighing
less than 4.9 kg/m2 (1.0 pound per square foot). For rooms with significant air pressure differential from adjacent spaces,
retention clips may be necessary to retain panels in place. Maintaining air pressure values may also require perimeter panel
seals, typically a closed cell foam gasket with adhesive on one side.
Concealed Mounting System – Tile suspension system using T-Bars and splines which fit into kerfs cut into tile edges. Unlike exposed-grid systems,
concealed mounting systems are not visible from below the ceiling. Inverted tee, "H and T," or "Z" profile grids are common
for these applications with provisions for full plenum access usually incorporated into the grid design.
Cross Runner, Cross Tee – The cross runner is the secondary or cross beams of a mechanical ceiling suspension system, usually supporting only the
acoustical tile. The cross tee is inserted into the main runner to form different module sizes. In some suspension systems,
however, the cross runners also provide support for lighting fixtures, air diffusers and other cross runners.
Deflection – Bending or deviation from a straight line or course. Used here as the standard by which allowable load for suspension system
components is measured.
Double Web – Indicates two layers of material in the construction of the vertical web of main runners and cross tees.
Downward Access System – Direct access is achieved by removing individual units by hand or may require an access clip or key. Multiple panels designed
as end- or side-pivoting units can also be used. The number of permissible access openings are fewer with an end pivot design.
Downward access may be desirable if tight plenum clearance is a problem. In fire-rated designs, the amount of each access
area and pan size is governed by testing criteria.
Duty Classification – Load carrying capability of grid main beams (per ASTM C635) pounds per lineal foot (Light: 5 lbs; Intermediate: 12 lbs;
Heavy: 16 lbs).
Electrogalvanized – A plating process that deposits a coating of zinc on a cold rolled steel substrate. Thickness or weight of coating can
be varied and is typically categorized as heavy-electro through standard-electro or "flash" electrogalvanized. Process providing
rust resistance for metal.
Environmental Systems – Grid systems that are made of base materials that withstand a variety of moist and corrosive conditions.
Exposed Grid System – Structural suspension system for lay-in ceiling panels. Factory-painted supporting members are exposed to view. Exposed
tee surfaces may be continuous or have an integral reveal. Reveals are typically formed as channel or rail profiles extending
down from the tee leg. Bolt-slot type reveal designs can accommodate partition attachment. The choice may be restricted by
appropriate tee width for panel selected and limitations on available panel edge details for the chosen grid profile.
Fixture Weight – Individual weight of mechanical services supported by ceiling grid members.
Flange – Horizontal surface on the face of the tee, visible from below the ceiling. The part of the grid to which the color cap
is applied. Most grid system flanges are either 15/16″or 9/16″.
Galvanized – A generic term used to describe a sheet or coil of steel coated with zinc applied in an electrogalvanizing or dipping process.
Gasketed Grid – Ceiling suspension system that has a gasketing attached to the top side of the flanges. Used in clean room ceilings to
seal the panels to the grid.
Gauge – Thickness of the steel used to make a grid member. May be expressed by a number designation (26 GA.) or in thousandths
of an inch (0.013).
Grid – Structural system of main beams, cross tees, and associated hardware which hangs from the deck above and supports lay-in,
concealed or surface attached ceiling panels.
Hanger Wires – Wire employed to suspend the acoustical ceiling from the existing structure. The standard material is 2.05 mm (12 gauge)
galvanized, soft annealed steel wire, conforming to ASTM A 641M or A 641. Heavier gauge wire is available for higher load
carrying installations, or situations where hanger wire spacing exceeds 1200 mm (4 feet) on center. Stainless steel wire and
nickel-copper alloy wire are frequently used in severe environment designs. Seismic designs or exterior installations subject
to wind uplift may require supplemental bracing or substantial hanger devices such as metal straps, rods or structural angles.
Heavy-Duty Systems – Primarily used for installations in which the quantities and weights of ceiling fixtures (lights, air diffusers, etc.)
are greater than those for an ordinary commercial structure.
Hold Down Clip – Mechanical fastener that snaps over the bulb of a grid system to hold ceiling panels in place.
Hook Tee – Cross tee with an end tab that hooks through the rout hole and rests on the vertical web of the main runner.
Hot Dipped Galvanized – Process to coat steel to offer environmental resistance to corrosion. Cold rolled steel is submerged (dipped) into a molten
zinc bath. A heavy coating of zinc is applied to the steel substrate. Zinc coating thickness varies and is designated by a
"G" series, such as G-60 or G-90.
Integral Splice – Connects the mains or tees together and is formed from the base metal of the components.
Intermediate-Duty Systems – These are used primarily for ordinary commercial structures where some ceiling loads, due to light fixtures and air diffusers,
L/360, Span/360 – The distance between support points of a suspension system member divided by 360. The result of this mathematical equation
is the maximum amount of deflection that is allowed under ASTM C 636.
Light-Duty Systems – Used primarily for residential and light commercial structures where ceiling loads other than acoustical tile or lay-in
panels are not anticipated.
Load – Amount of force (weight) that is applied to a lineal foot of any load bearing member of a ceiling system.
Main Beam, Main Runner, Main Tee – Primary or main beams of the type of ceiling suspension system in which the structural members are mechanically locked
together. Provide direct support for cross runners and may support lighting fixtures and air diffusers, as well as the acoustical
tile. Supported by hanger wires attached directly to the existing structure; or installed perpendicular to carrying channels
and supported by specially designed sheet metal or wire clips attached to the carrying channels. Typically a 12′piece located
4' on center.
ML – Cross tee end detail that is a "hook" insertion contrasted with the XL that is "stab" insertion. The ML end detail is quick
and easy to install; however, it does not meet most seismic requirements greater than IBC Seismic Design Category C.
Override – Offset on the end of some cross tees that rests on top of the supporting member’s flange. Increases stability and moves
cut edge of tee out of the visible plane of the ceiling.
PeakForm – An improvement in the main beam bulb design from a rectangular shape to one that culminates to a point, or peak. Unique
profile increases strength and stability of grid during installation.
Rotary Stitching – Process by which two vertical layers (double web) of steel are stitched or bonded together to form a more homogeneous component
exhibiting increased column strength, torsional strength and overall handleability. Armstrong is the only grid manufacturer
to employ this technology.
Semi-Concealed Installation System – Installation system in which tile kerfs are shallow enough to leave gaps between the tiles in one direction, exposing the
grid on two sides. Usually an inverted grid. Two opposing panel edges are fabricated for a concealed grid profile.
Seismic Compression/Tension – The capability of a grid member connection to carry a mean ultimate test load in compression/tension.
Shadow Molding – A W-shaped molding that will produce a reveal or space between the ceiling and the wall when fastened to the wall.
Slotted Systems – Either bolt-slot or screw-slot systems, both of which offer a dimensional look to an otherwise flush ceiling using 9/16″exposed
components. Typically feature a 1/8″or 1/4″groove that runs down the center of the components.
Spline – A strip of metal or fiber inserted in the kerfs of adjacent acoustical tile to form a concealed mechanical joint seal.
Stab End Detail – Provides a tee to tee lock. Designed to be inserted with a forward motion.
Stabilizer Bar – U-shaped channel, either 24′long or 48′long, designed to maintain cross tee spacing at the perimeter. Used in seismic installations
to help prevent cross tees and panels from falling from the suspension system during an earthquake.
Stiffening Brace – Used to prevent uplift of grid caused by wind pressure in exterior applications.
Stitching – Dimples impressed in grid members to knit the webs together. (See Rotary Stitching)
Superlock – Main beam end detail that is a staked-on clip to splice main beams together. This clip provides a strong, secure connection
that is easy to remove and relocate.
Suspension System – A metal grid suspended from hanger rods or wires, consisting of main beams and cross tees, clips, splines and other hardware
which supports lay-in acoustical panels or tiles. The completed ceiling forms a barrier to sound, heat and fire. It also absorbs
in-room sound and hides ductwork and wiring in the plenum.
T-Bar – Any metal member of "T" cross section used in ceiling suspension systems.
UL 580 – Wind uplift test (Class 15 – 15 lbs/sf; Class 90 – 90 lbs/sf).
Wind Uplift – Resistance to wind uplift forces may be necessary for exterior
ceiling and soffit designs. A substantial hanger system design, incorporating rods or straps, plus acoustical unit retention
clips, is commonly required. Verify code requirements for wind uplift force resistance and manufacturer’s recommendations
for ceiling installations based on these values.
XL - Cross tee and detail that is staked on and provides a secure lock connection; tee to tee stab insertion, easy to remove,
reuse and relocate. Meets IBC Seismic Design Category DEF.
Z-Bar Concealed – Metal strips which are attached to a 1-1/2″carrying channel, one foot on center and at right angles to the channel. Also
called Zee runners.