# Ceiling Systems

## Ceiling Type Selection

### Decision Tree
```
What is the use?
  Office/Commercial → ACT or drywall
  Residential → Drywall or exposed
  Industrial → Exposed structure
  Wet areas → Moisture-resistant

What is the budget?
  Economy → ACT (lay-in)
  Mid-range → Tegular ACT or basic drywall
  Premium → Specialty ACT, wood, or detailed drywall

Is MEP access needed?
  Frequent access → ACT (lay-in)
  Occasional → ACT tegular or access panels in drywall
  Minimal → Drywall
```

---

## Acoustical Ceiling Tile (ACT)

### Grid Systems
| Type | Reveal | Aesthetic |
|------|--------|-----------|
| Exposed tee (lay-in) | 15/16" or 9/16" | Standard commercial |
| Tegular | 15/16" | Shadow line, upscale |
| Concealed spline | 0" | Clean, minimal |
| Bandraster | Varies | Linear accent |

### Tile Sizes
| Size | Application |
|------|-------------|
| 2' × 2' | Office, institutional |
| 2' × 4' | Commercial, budget |
| 1' × 1' | Medical, specialty |
| Planks | Corridor, accent |

### Tile Types
| Type | NRC | CAC | Use |
|------|-----|-----|-----|
| Mineral fiber (standard) | 0.50-0.70 | 25-35 | General office |
| Mineral fiber (high NRC) | 0.70-0.90 | 30-40 | Conference, focus |
| Fiberglass | 0.80-1.0 | 25-35 | High absorption |
| Metal (perforated) | 0.50-0.80 | 20-30 | Modern, clean rooms |
| Wood (perforated) | 0.60-0.80 | 20-30 | High-end |
| Vinyl-faced | 0.50-0.60 | 25-35 | Food service, wet |

### Performance Ratings
| Rating | Description | Value Range |
|--------|-------------|-------------|
| NRC | Noise Reduction Coefficient | 0-1.0 (higher = more absorption) |
| CAC | Ceiling Attenuation Class | 25-45 (higher = better isolation) |
| LR | Light Reflectance | 0.75-0.90 typical |
| Humidity | Sag resistance | 70%-99% RH tolerance |

---

## Drywall Ceilings

### Assembly Types
| Type | Layers | Fire Rating |
|------|--------|-------------|
| Standard | 1 × 1/2" GWB | None |
| Fire-rated (1-hr) | 1 × 5/8" Type X | 1 hour |
| Fire-rated (2-hr) | 2 × 5/8" Type X | 2 hours |
| Moisture-resistant | Green board or purple | None |
| Abuse-resistant | 5/8" high-impact | None |

### Suspension Systems
| System | Span | Application |
|--------|------|-------------|
| Resilient channel | 16"-24" O.C. | Sound isolation |
| Hat channel | 16"-24" O.C. | Standard |
| Direct attach | N/A | Joists/deck |
| Grid (drywall grid) | 4' O.C. | Large spans, commercial |

### Level of Finish
| Level | Description | Use |
|-------|-------------|-----|
| Level 3 | Tape + one coat | Hidden areas |
| Level 4 | Tape + two coats | Standard (flat paint) |
| Level 5 | Skim coat | High gloss, critical lighting |

---

## Specialty Ceilings

### Wood Ceilings
| Type | Cost | Acoustic | Maintenance |
|------|------|----------|-------------|
| Solid wood planks | $$$$ | Poor (unless perforated) | Medium |
| Wood veneer panels | $$$ | Varies | Low |
| Perforated wood | $$$$ | Good | Low |
| Linear wood (grille) | $$$$ | Good | Medium |

### Metal Ceilings
| Type | Application | Cost |
|------|-------------|------|
| Lay-in metal | Modern office | $$$ |
| Linear metal | Corridor, retail | $$$ |
| Mesh/expanded | Industrial modern | $$$ |
| Tin/pressed | Historic, residential | $$ |

### Specialty Materials
| Type | Application |
|------|-------------|
| Fabric-wrapped panels | Auditorium, theater |
| Stretched fabric | Modern, colored |
| Acoustic baffles | Open ceiling, absorption |
| Acoustic clouds | Floating, design statement |
| Translucent (backlit) | Feature, wayfinding |

---

## Open/Exposed Ceilings

### When to Use
- Industrial/loft aesthetic
- High ceilings (14'+ economical)
- Sustainability (less material)
- Flexibility (exposed access)

### What to Address
- Structure painted or sealed
- MEP systems organized and painted
- Acoustic treatment (baffles, spray-on, clouds)
- Fire sprinkler coverage
- Lighting (pendant, track, surface)

### Acoustic Solutions for Open Ceilings
| Solution | NRC | Application |
|----------|-----|-------------|
| Spray-on acoustic | 0.70-0.90 | Deck underside |
| Acoustic baffles | 0.80-1.0 | Suspended linear |
| Acoustic clouds | 0.80-1.0 | Suspended horizontal |
| Wall panels | 0.80-1.0 | Perimeter walls |

---

## Heights and Clearances

### Minimum Ceiling Heights
| Space | Min Height |
|-------|------------|
| Residential habitable | 7'-0" |
| Residential bathroom | 7'-0" (may be lower over fixtures) |
| Commercial office | 8'-0" |
| Commercial corridor | 7'-6" |
| Assembly (theater) | Varies, typically 10'+ |
| Mechanical room | 7'-0" or per equipment |
| Restroom | 7'-0" |

### ADA Clearances
- 80" min clear height along accessible route
- Protruding objects: max 4" if above 27" AFF
- Objects below 27" may project any amount

### Clearance to Structure
| System | Min Clearance |
|--------|---------------|
| ACT grid | 4" min (6" preferred) |
| Drywall on furring | 1.5" min |
| Sprinkler head | 1"-12" below ceiling |
| Light fixture | Per fixture requirement |
| Diffuser | Per duct requirement |

---

## Reflected Ceiling Plans (RCP)

### What to Show
- Ceiling material/type boundaries
- Grid layout (start point, orientation)
- Light fixtures (type mark)
- Diffusers/registers
- Sprinkler heads
- Access panels
- Speakers/AV
- Exit signs
- Smoke detectors
- Ceiling heights (if varying)
- Soffits/bulkheads

### RCP Notes
```
CEILING NOTES:
1. ALL CEILING TILES: 2'×2' MINERAL FIBER,
   NRC 0.70 MIN, WHITE, SQUARE EDGE
2. GRID: 15/16" EXPOSED TEE, WHITE
3. LAY OUT CEILING GRID FROM CENTER OF ROOM
4. ALL TILES FULL SIZE AT PERIMETER UNLESS
   NOTED (MIN TILE SIZE: 12")
5. COORDINATE LIGHTS, DIFFUSERS, AND
   SPRINKLERS FOR CENTERED PLACEMENT
6. VERIFY CEILING HEIGHT WITH STRUCTURAL
```

### Coordination Checklist
- [ ] Grid aligned with walls/columns
- [ ] Light fixtures centered in tiles
- [ ] Diffusers centered in tiles
- [ ] Sprinklers centered in tiles (or between tiles)
- [ ] Access panels located per MEP needs
- [ ] Speakers coordinated with acoustics
- [ ] Exit signs on egress path
- [ ] Smoke detectors per code

---

## Fire-Rated Ceiling Assemblies

### Common Assemblies
| UL Design | Description | Rating |
|-----------|-------------|--------|
| L501 | Mineral fiber on steel grid | 1-hr |
| L514 | Mineral fiber on steel grid | 2-hr |
| L528 | GWB on steel framing | 1-hr |
| P-series | GWB on wood framing | Varies |

### Requirements
- All materials listed in assembly
- Penetrations properly firestopped
- Hold-down clips if required
- Sprinklers if specified

### Ceiling Membrane Penetrations
| Item | Treatment |
|------|-----------|
| Recessed light | Listed for use in fire-rated assembly |
| Sprinkler | May penetrate if listed |
| Diffuser | Listed boot or rated ceiling diffuser |
| Access panel | Listed fire-rated panel |
| Speaker | Listed for use in fire-rated assembly |

---

## Wet/High Humidity Ceilings

### Moisture-Resistant Options
| Material | Max RH | Application |
|----------|--------|-------------|
| Vinyl-faced ACT | 95% | Food service, locker |
| Fiberglass ACT | 99% | Pool, spa |
| Aluminum | 100% | Exterior soffit, pool |
| Fiber cement | 100% | Exterior, wet |
| Green board GWB | 70% | Residential bath |
| Glass mat GWB | 95% | Commercial wet |
| Cement board | 100% | Shower, tub surround |

### Pool/Natatorium
- Fiberglass or aluminum tiles
- Stainless steel or aluminum grid
- Anti-corrosive finishes throughout
- Vapor barrier above
- Dehumidification required

---

## Acoustical Planning

### Space-by-Space NRC Goals
| Space | Target NRC |
|-------|------------|
| Open office | 0.70-0.85 |
| Private office | 0.60-0.75 |
| Conference | 0.70-0.85 |
| Classroom | 0.60-0.75 |
| Corridor | 0.50-0.60 |
| Cafeteria | 0.75-0.90 |
| Lobby | 0.60-0.75 |

### Space-by-Space CAC Goals
| Space | Target CAC |
|-------|------------|
| Private office | 35-40 |
| Conference | 40+ |
| Healthcare exam | 40+ |
| Hotel room | 45+ |
| Classroom | 35-40 |

### Sound Masking
- 40-48 dBA typical target
- Speakers above ceiling or integrated
- Uniform coverage
- Adjustable zones
