# Acoustic Ceiling Tile [ACT]

> ACT (acoustic ceiling tile) is a lay-in ceiling panel set in a suspended grid. Tile sizes, edge types, NRC vs CAC ratings, materials and installation checks.

- URL: https://essential.construction/academy/glossary/acoustic-ceiling-tile/
- Author: Kyle Parry (https://essential.construction/about-us/kyle-parry/, https://www.linkedin.com/in/kyleparry/) - Kyle Parry is the founder of Essential Construction. He has worked in construction for more than 20 years, leading projects across Canada for the country's largest contractors and developers.
- Publisher: Essential Construction (https://essential.construction/)
- Last updated: 2026-11-03

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**Acoustic ceiling tile (ACT)** is a lightweight lay-in ceiling panel set into a suspended metal grid that hangs from the structure above. ACT absorbs sound, hides ducts, pipes and wiring, and can be lifted out for access, which makes it the standard ceiling in offices, schools and other commercial buildings.

## How an ACT ceiling is built

- **Hanger wires** tie the grid to the structure above.
- **Main runners** (main tees) span the room and hang from the wires.
- **Cross tees** clip between the mains to form the grid modules.
- **Wall angle or moulding** supports the grid at the perimeter.
- **Tiles** drop into the grid, along with lights, diffusers and sprinkler heads.

In North America, ASTM C635 covers the grid and ASTM C636 its installation (hanger wires are typically 12 gauge at no more than 4 ft on centre). In higher seismic areas, ASTM E580 and the building code add bracing and wider perimeter supports.

## Tile sizes and edge types

| Option | Details |
| --- | --- |
| Common sizes | 2x2 ft and 2x4 ft; metric projects use 600x600 and 600x1200 mm |
| Grid width | 15/16 in standard face; 9/16 in narrow face |
| Square lay-in edge | Tile sits flush on the grid; cheapest and easiest |
| Tegular edge | Stepped edge drops the tile face below the grid for a shadow line |
| Concealed edge | Kerfed edges hide the grid for a near-monolithic look |

## Ratings to know

- **NRC (noise reduction coefficient):** how much sound the tile absorbs, usually expressed from 0 to 1. Higher means less echo in the room.
- **CAC (ceiling attenuation class):** how well the ceiling blocks sound passing between rooms through the plenum. Higher is better.
- **Fire performance:** surface burning class, and whether the ceiling is part of a rated floor or roof assembly.
- **Humidity and sag resistance, light reflectance and cleanability** for washrooms, kitchens and healthcare.

ASTM E1264 classifies acoustical ceiling products by type, pattern and fire class.

## Materials

Mineral fibre is the most common. Fibreglass tiles give high sound absorption, metal and wood panels suit feature ceilings, and vinyl-faced or washable tiles suit food and healthcare spaces.

## Installation and coordination tips

- Coordinate the reflected ceiling plan with ducts, sprinklers, lights and [access](https://essential.construction/academy/glossary/access-panel/) needs before the grid goes up.
- Hang wires from the structure, not from ducts or pipes, and support heavy fixtures independently.
- Install tiles only after the building is closed in and humidity is controlled, or they can sag.
- Handle tiles with clean gloves and leave spare "attic stock" for the owner.

## Related terms

- [Access Panel](https://essential.construction/academy/glossary/access-panel/)
- [Ductwork](https://essential.construction/academy/glossary/ductwork/)
- [Fan Coil Unit](https://essential.construction/academy/glossary/fan-coil-unit/)
- [Mockup](https://essential.construction/academy/glossary/mockup/)

## Related templates and guides

- [QA/QC Checklist: Acoustic Ceiling Tile (ACT)](https://essential.construction/files/construction/quality/qaqc-checklist-acoustic-ceiling-tile-act/)
- [Suspended Ceiling Installation Productivity Monitoring Form](https://essential.construction/files/construction/scheduling/suspended-ceiling-installation-productivity-monitoring-form/)
- [Deficiency Log Template](https://essential.construction/files/construction/quality/deficiency-log-template/)
- [Interior Finishes: Designing With Use in Mind](https://essential.construction/academy/tutorials/interior-finishes-designing-with-use-in-mind/)

## Frequently asked questions

### What does ACT stand for in construction?

ACT stands for acoustic (or acoustical) ceiling tile: the lay-in panels in a suspended grid ceiling. On drawings and finish schedules, 'ACT-1', 'ACT-2' and so on identify each tile and grid combination specified for the project.

### What size are ACT tiles?

The common sizes are 2x2 ft and 2x4 ft in North America, and 600x600 mm and 600x1200 mm on metric projects. Larger and plank formats exist for feature ceilings, but they need matching grid and more careful handling.

### What is the difference between NRC and CAC?

NRC measures how much sound a tile absorbs inside the room, which reduces echo. CAC measures how well the ceiling stops sound travelling over a wall through the plenum into the next room. Open offices care about NRC; private offices need CAC too.

### What is a tegular ceiling tile?

A tegular tile has a stepped edge so its face sits slightly below the grid. That creates a shadow line around each tile and hides minor grid imperfections. Tegular tiles cost a little more than square lay-in tiles and need careful cutting at walls.