Ceiling Grid Components Guide

Every part of a suspended ceiling grid system explained — what it does, how it connects, and what to specify. A reference for architects, GCs, and facility managers who need to understand what's holding the ceiling up.

How the System Works

A suspended ceiling grid is a network of metal tees hung from the structure above by wires. Main tees run the length of the room, cross tees snap into the main tees to create a grid pattern, and wall angles support the grid at the room perimeter. Ceiling tiles drop into the openings formed by the grid. The entire assembly hangs below the structural deck, creating a plenum space above for HVAC, electrical, and plumbing systems.

    STRUCTURAL DECK (concrete, metal, wood)
    ═══════════════════════════════════════════════
         │              │              │
         │ Hanger       │ Hanger       │ Hanger
         │ Wire         │ Wire         │ Wire
         │              │              │
    ─────┼──────────────┼──────────────┼───── ← Main Tee (12' lengths)
         │              │              │
    ─────┤    TILE      ├──────────────┤───── ← Cross Tee (2' or 4')
         │              │              │
    ─────┼──────────────┼──────────────┼───── ← Main Tee
         │              │              │
    ┌────┘              └──────────────┘────┐
    │                WALL ANGLE              │ ← Perimeter support
    └───────────────────────────────────────┘
                    WALL

Main Tees (Main Runners)

The backbone of the grid system. Main tees are T-shaped metal runners that span the room in one direction, typically the long direction. They carry the weight of the entire ceiling — tiles, cross tees, light fixtures, and diffusers.

Standard lengths: 12 feet, spliced together for longer runs
Spacing: 4 feet on center (for 2×4 layout) or 2 feet on center (for 2×2 layout with main tees in both directions)
Face widths: 15/16" (standard) or 9/16" (narrow/architectural)
Profiles: Inverted T-shape. The vertical web provides structural depth; the horizontal flanges support tiles
Splicing: Main tees connect end-to-end with locking splice joints. In seismic zones, splices may require rivets
Duty rating: Standard, intermediate, or heavy-duty based on steel gauge and web depth

Cross-Section:

    ┌─┐
    │ │ ← Web (1" to 1-1/2" deep)
    │ │
  ──┴─┴──
  Flange  ← 15/16" or 9/16"

Cross Tees

Cross tees snap into slots in the main tees at right angles, creating the grid openings that hold tiles. They're shorter than main tees and don't carry as much load.

4-foot cross tees: Span between main tees (which are 4' apart). Create 2×4 openings. Required in every grid layout.
2-foot cross tees: Snap into the midpoint of 4-foot cross tees, dividing 2×4 openings into 2×2 openings. Only needed for 2×2 tile layouts.
Connection: Tab-and-slot or hook-and-slot that clicks into main tee slots. In seismic zones, connections may need to be riveted for positive attachment.
Face width: Matches main tees (15/16" or 9/16"). All grid components in a system must have the same face width.

Key detail: Cross tee tabs and main tee slots are system-specific. You can't mix cross tees from one manufacturer with main tees from another — the connections won't engage properly.

Wall Angle (Wall Molding)

An L-shaped metal angle attached to the wall around the room perimeter. The grid rests on the wall angle at the edges. Think of it as the shelf that supports the grid at the walls.

Standard size: 7/8" × 7/8" with 12-foot lengths
Installation: Screwed or shot-pinned to the wall at the ceiling height line. Must be level — any variation shows as a visible dip or hump at the ceiling edge.
Seismic consideration: In California, the grid cannot simply rest on the wall angle — it needs seismic clips that allow lateral movement while preventing the grid from falling off the angle. A 3/4" gap between the grid end and the wall face allows movement during an earthquake.
Shadow molding: An upgraded perimeter detail where the wall angle creates a deliberate shadow gap between the ceiling plane and the wall. More architectural than a standard butt joint.

Hanger Wire

Steel wire that suspends the main tees from the structural deck or framing above. The wires carry the dead load (weight) of the entire ceiling assembly.

Wire gauge: 12-gauge galvanized steel wire is standard. Heavy ceilings or seismic applications may require 10-gauge.
Spacing: Maximum 4 feet on center in each direction. Closer spacing for heavy loads (large fixtures, heavy tiles).
Attachment above: Wire wraps around structural members, inserts, shot pins, or concrete anchors in the deck above. Three tight wraps minimum at each end.
Attachment below: Wire passes through a hole in the main tee web and wraps back on itself with three tight turns.
Verticality: Wires must hang within a 1:6 slope ratio — no more than 1 foot of horizontal offset per 6 feet of wire length. Excessively angled wires don't support load properly.

Seismic Components

Required in California (all seismic design categories C-F)

Compression Struts

Rigid posts between the grid and structure that resist upward movement during seismic events. Hanger wires only resist downward forces — they go slack when the ceiling bounces up. Compression struts prevent this upward displacement that can disconnect grid components. Typically spaced every 12 feet and within 2 feet of expansion joints.

Splay Wires (Lateral Bracing)

Diagonal wires at approximately 45 degrees from the grid to the structure, resisting horizontal movement. Installed in opposing pairs to brace against forces in both directions. Required at perimeters and at regular intervals across the ceiling field.

Seismic Clips

At the wall perimeter, clips connect the grid to the wall angle while allowing controlled lateral movement. They prevent the grid from sliding off the wall angle during shaking. The 3/4" gap between grid end and wall accommodates this movement.

Pop Rivets

Used at main tee splices and cross tee connections to create positive mechanical connections that won't pull apart during shaking. Friction-fit connections alone are not reliable in seismic events.

For complete seismic requirements, see our seismic ceiling requirements guide and California seismic bracing blog post.

Accessories

Hold-Down Clips

Spring clips that hold tiles down in the grid, preventing uplift from air pressure differentials or vibration. Common in return air plenum ceilings and above HVAC equipment.

Stabilizer Bars

Metal bars that stiffen the grid at light fixture locations, preventing sagging from heavy recessed fixtures. Required when fixture weight exceeds the grid's load capacity at that span.

Grid Covers / Caps

Snap-on covers that change the appearance of exposed grid. Available in colors, wood grain, and wider profiles. An upgrade option without replacing the entire grid.

Transition Moldings

Used where the ceiling changes height, meets a soffit, or transitions between different ceiling types. Creates a clean joint between ceiling planes.

Grid Duty Ratings

Rating	Load Capacity	Use Case
Standard Duty	Up to 16 lb/LF of main tee	Non-seismic zones, light tile, minimal fixtures
Intermediate Duty	Up to 24 lb/LF	Standard California installations, moderate fixtures
Heavy Duty	Up to 32+ lb/LF	High seismic zones, heavy tiles/fixtures, essential facilities