# Roof Assemblies - Types and Applications

## Decision Logic

### Roof Type Selection
```
What is the building type?
  Residential → Typically pitched (shingles, tile, metal)
  Commercial → Often flat (built-up, TPO, EPDM)

What is the climate?
  Florida/Coastal → Impact-rated, wind uplift resistance
  Heavy snow → Steeper pitch, stronger structure
  Desert → Cool roof, reflective

What is the budget?
  Economy → Asphalt shingles, TPO
  Mid-range → Metal panel, modified bitumen
  Premium → Standing seam, tile, slate
```

---

## Pitched Roof Assemblies

### Type PR-1: Asphalt Shingle (Standard Residential)
**Use when:** Budget residential, 4:12 to 12:12 pitch
```
Top to Bottom:
- Asphalt shingles (30-year or better)
- Synthetic underlayment (or 30# felt)
- 1/2" plywood or 7/16" OSB sheathing
- Roof trusses or rafters @ 24" O.C.
- R-30 to R-38 insulation (at ceiling)
- Ceiling GWB
```
**Min Pitch:** 4:12 (2:12 with special underlayment)
**Wind Rating:** 110-130 mph standard, 150+ available

### Type PR-2: Metal Panel (Residential/Light Commercial)
**Use when:** Longer lifespan, modern aesthetic, 3:12 to 12:12
```
Top to Bottom:
- Standing seam or exposed fastener metal
- Synthetic underlayment
- 1/2" plywood or OSB sheathing
- Roof trusses or rafters
- R-30 to R-38 insulation
- Ceiling GWB
```
**Min Pitch:** 3:12 (standing seam), 1:12 possible with sealant
**Lifespan:** 40-70 years
**Wind Rating:** Up to 180 mph (standing seam)

### Type PR-3: Concrete/Clay Tile (Florida/Coastal)
**Use when:** Hurricane zones, Spanish/Mediterranean style
```
Top to Bottom:
- Concrete or clay tile
- Tile underlayment (2-ply or peel-stick)
- 30# felt or synthetic
- 5/8" or 3/4" plywood (required for tile weight)
- Roof trusses (designed for tile load)
- Hurricane clips at every truss
- R-30 to R-38 insulation
- Ceiling GWB
```
**Min Pitch:** 4:12
**Weight:** 9-12 psf (design structure accordingly)
**Wind Rating:** Up to 180 mph

### Type PR-4: Standing Seam Metal (Premium)
**Use when:** High wind, long lifespan, minimal maintenance
```
Top to Bottom:
- Standing seam panels (24 ga min for wind)
- High-temp ice & water shield
- 5/8" plywood sheathing
- Engineered trusses or rafters
- Continuous ridge vent
- R-38+ insulation
- Ceiling GWB
```
**Min Pitch:** 1:12 possible, 3:12 recommended
**Lifespan:** 50+ years
**Wind Rating:** 180+ mph (with proper clips)

---

## Flat Roof Assemblies

### Type FR-1: Built-Up Roof (BUR)
**Use when:** Commercial, budget, roof traffic expected
```
Top to Bottom:
- Gravel or cap sheet
- 3-4 plies of felt + bitumen
- Base sheet
- Rigid insulation (tapered for drainage)
- Cover board
- Vapor barrier
- Metal deck or concrete deck
```
**Slope:** 1/4" per foot minimum
**Lifespan:** 15-30 years

### Type FR-2: TPO/PVC Single-Ply
**Use when:** Commercial, white roof, energy efficiency
```
Top to Bottom:
- TPO or PVC membrane (60-80 mil)
- Adhered, mechanically attached, or ballasted
- Cover board (1/2" HD ISO or gypsum)
- Polyiso insulation (tapered)
- Vapor barrier
- Metal deck
```
**Slope:** 1/4" per foot minimum
**Lifespan:** 20-30 years
**Cool Roof:** Yes (high reflectivity)

### Type FR-3: Modified Bitumen
**Use when:** Commercial, some residential flat, good durability
```
Top to Bottom:
- Modified bitumen cap sheet (torch or cold-applied)
- Modified bitumen base sheet
- Rigid insulation (tapered)
- Vapor barrier
- Metal or concrete deck
```
**Slope:** 1/4" per foot minimum
**Lifespan:** 20-25 years

### Type FR-4: EPDM Rubber
**Use when:** Commercial, budget, easy repair
```
Top to Bottom:
- EPDM membrane (45-60 mil)
- Adhered or mechanically attached
- Cover board
- Polyiso insulation
- Vapor barrier
- Deck
```
**Slope:** 1/4" per foot minimum
**Lifespan:** 20-25 years

---

## Roof Insulation Requirements

### Florida Climate (Zone 1-2)
| Roof Type | Minimum R-Value |
|-----------|-----------------|
| Attic (ceiling insulation) | R-30 |
| Roof deck (no attic) | R-25 |
| Metal building | R-19 |

### Insulation Types
| Type | R-Value per inch | Use |
|------|------------------|-----|
| Fiberglass batt | R-3.2 | Attic floors |
| Blown cellulose | R-3.5 | Attic floors |
| Polyiso board | R-6.0 | Roof decks |
| XPS board | R-5.0 | Below membrane |
| Spray foam (closed) | R-6.5 | Cathedral ceilings |

---

## Drainage Requirements

### Minimum Slopes
| Roof Type | Minimum Slope |
|-----------|---------------|
| Flat (membrane) | 1/4" per foot |
| Low slope metal | 1/2" per foot |
| Shingle | 4:12 (with provisions at 2:12) |
| Tile | 4:12 |

### Drainage Calculation
For flat roofs:
- Primary drains: 1 per 10,000 SF (or per code)
- Overflow: 2" above primary or scuppers
- Scupper size: 4" minimum height
- Gutter: 1" per 100 SF roof area (5" gutter per 500 SF)

---

## Florida/Hurricane Specific

### Wind Uplift Zones
| Zone | Location | Pressure |
|------|----------|----------|
| Zone 1 | Field | Lowest |
| Zone 2 | Perimeter | Medium |
| Zone 3 | Corners | Highest |

### Required Uplift Resistance
| Wind Speed | Field | Perimeter | Corner |
|------------|-------|-----------|--------|
| 130 mph | -45 psf | -67 psf | -90 psf |
| 150 mph | -60 psf | -90 psf | -120 psf |
| 180 mph | -90 psf | -135 psf | -180 psf |

### Miami-Dade Requirements
- Product must have NOA (Notice of Acceptance)
- Testing to TAS 100/105/107
- Impact resistance if within 30' of grade

### Secondary Water Barrier
Florida Building Code requires for:
- Shingle roofs in HVHZ
- Peel-and-stick or spray foam under shingles
- Covers entire deck

---

## Roof Penetrations

### Standard Penetrations
| Item | Flashing Type | Notes |
|------|---------------|-------|
| Plumbing vent | Lead or rubber boot | Flash 4" min all sides |
| HVAC curb | Raised curb + counter-flash | 8" min curb height |
| Skylight | Integral flange | Cricket if >30" wide |
| Chimney | Step flashing + cricket | Cricket if >30" wide |

### Best Practices
- Minimize penetrations
- Group penetrations together
- Keep away from valleys and ridges
- Cricket behind any penetration >30" wide
