# Roof Construction Templates
### Roof Type 1: Vented Attic with Asphalt Shingles
**Most common residential roof system in North America**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| ------------------------ | ---------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | ------------------ |
| Exterior | Asphalt shingles | 1/8" | 3 mm | k = 0.43 Btu/(hr·ft·°F)\
λ = 0.74 W/(m·K) | Negligible |
| Underlayment | Felt or synthetic (Class III) | - | - | - | - |
| Sheathing | OSB or plywood | 1/2" | 13 mm | k = 0.077 Btu/(hr·ft·°F)\
λ = 0.133 W/(m·K) | R-0.6 (RSI-0.11) |
| **Ventilation** | **Attic space (vented)** | **Variable** | **Variable** | **-** | **-** |
| Insulation (attic floor) | Blown fiberglass or cellulose | 14" | 356 mm | k = 0.027 Btu/(hr·ft·°F)\
λ = 0.047 W/(m·K) | R-49 (RSI-8.6) |
| Air/vapor control | Ceiling gypsum acts as air barrier | - | - | - | - |
| Interior | Gypsum drywall | 1/2" | 13 mm | k = 0.096 Btu/(hr·ft·°F)\
λ = 0.166 W/(m·K) | R-0.45 (RSI-0.08) |
**Total Assembly: R-50 hr·ft²·°F/Btu (RSI-8.8 m²·K/W)**
**Notes:** Attic requires minimum 1:150 net free ventilation area (soffit to ridge). Insulation must not block ventilation at eaves. This is the cheapest way to hit code minimums, which is why it's everywhere.
***
### Roof Type 2: Cathedral Ceiling with Fiberglass Batts
**Vaulted ceiling with limited depth for insulation**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| --------------- | --------------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | -------------------- |
| Exterior | Asphalt shingles | 1/8" | 3 mm | k = 0.43 Btu/(hr·ft·°F)\
λ = 0.74 W/(m·K) | Negligible |
| Underlayment | Synthetic roof underlayment (Class III) | - | - | - | - |
| Sheathing | OSB or plywood | 1/2" | 13 mm | k = 0.077 Btu/(hr·ft·°F)\
λ = 0.133 W/(m·K) | R-0.6 (RSI-0.11) |
| **Ventilation** | **Air space (min. 2")** | **2"** | **50 mm** | **-** | **R-1.0 (RSI-0.18)** |
| Baffles | Ventilation baffles | - | - | - | - |
| Structure | Rafters (16" OC) | 9-1/2" (2x10) | 241 mm | k = 0.080 Btu/(hr·ft·°F)\
λ = 0.138 W/(m·K) | R-11.9 (RSI-2.09) |
| Insulation | Fiberglass batt | 7-1/2" | 190 mm | k = 0.027 Btu/(hr·ft·°F)\
λ = 0.047 W/(m·K) | R-28 (RSI-4.9) |
| Air barrier | Vapor-intelligent membrane (Variable) | - | - | - | - |
| Interior | Gypsum drywall | 1/2" | 13 mm | k = 0.096 Btu/(hr·ft·°F)\
λ = 0.166 W/(m·K) | R-0.45 (RSI-0.08) |
**Total Assembly: R-30 hr·ft²·°F/Btu (RSI-5.3 m²·K/W)**
**Notes:** The 2" ventilation gap eats into your available insulation depth, which is why cathedral ceilings struggle to meet modern energy codes. You're borrowing from thermal performance to prevent ice dams and moisture issues.
***
### Roof Type 3: Unvented Cathedral with Spray Foam
**High-performance cathedral ceiling without ventilation**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| ------------ | --------------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | ------------------ |
| Exterior | Asphalt shingles | 1/8" | 3 mm | k = 0.43 Btu/(hr·ft·°F)\
λ = 0.74 W/(m·K) | Negligible |
| Underlayment | Synthetic roof underlayment (Class III) | - | - | - | - |
| Sheathing | OSB or plywood | 1/2" | 13 mm | k = 0.077 Btu/(hr·ft·°F)\
λ = 0.133 W/(m·K) | R-0.6 (RSI-0.11) |
| Structure | Rafters (16" OC) | 11-1/4" (2x12) | 286 mm | k = 0.080 Btu/(hr·ft·°F)\
λ = 0.138 W/(m·K) | R-14.1 (RSI-2.47) |
| Insulation | Closed-cell spray foam | 11-1/4" | 286 mm | k = 0.016 Btu/(hr·ft·°F)\
λ = 0.028 W/(m·K) | R-67 (RSI-11.8) |
| Interior | Gypsum drywall | 1/2" | 13 mm | k = 0.096 Btu/(hr·ft·°F)\
λ = 0.166 W/(m·K) | R-0.45 (RSI-0.08) |
**Total Assembly: R-68 hr·ft²·°F/Btu (RSI-12.0 m²·K/W)**
**Notes:** Closed-cell foam acts as its own air barrier and vapor control (Class II). No ventilation required, which gives you the full rafter depth for insulation. Expensive, but effective. Building inspectors may want to see code references the first time you try this.
***
### Roof Type 4: Flat/Low-Slope EPDM Membrane
**Commercial rubber membrane roof**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| -------------- | -------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | ------------------ |
| Exterior | EPDM rubber membrane | 60 mil | 1.5 mm | k = 0.13 Btu/(hr·ft·°F)\
λ = 0.225 W/(m·K) | Negligible |
| Cover board | Gypsum cover board | 1/2" | 13 mm | k = 0.096 Btu/(hr·ft·°F)\
λ = 0.166 W/(m·K) | R-0.45 (RSI-0.08) |
| Insulation | Polyiso rigid foam | 4" | 100 mm | k = 0.014 Btu/(hr·ft·°F)\
λ = 0.024 W/(m·K) | R-24 (RSI-4.2) |
| Vapor retarder | Self-adhered membrane (Class II) | - | - | - | - |
| Roof deck | Steel deck | 22 ga | 0.76 mm | k = 314 Btu/(hr·ft·°F)\
λ = 543.5 W/(m·K) | Negligible |
| Structure | Open-web steel joists | Variable | Variable | - | - |
| Interior | Suspended ceiling or exposed | - | - | - | - |
**Total Assembly: R-24.5 hr·ft²·°F/Btu (RSI-4.3 m²·K/W)**
**Notes:** The vapor retarder location is critical. Get it wrong and you'll condense moisture at the deck, which steel doesn't appreciate. Tapered insulation creates positive drainage because perfectly flat roofs are a myth.
***
### Roof Type 5: Modified Bitumen with Ballast
**Commercial torch-down or cold-applied membrane**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| -------------- | -------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | ------------------ |
| Exterior | River stone ballast | 3" | 75 mm | k = 1.50 Btu/(hr·ft·°F)\
λ = 2.60 W/(m·K) | R-2.0 (RSI-0.35) |
| Membrane | Modified bitumen (2-ply) | 1/4" | 6 mm | k = 0.11 Btu/(hr·ft·°F)\
λ = 0.19 W/(m·K) | Negligible |
| Insulation | EPS rigid foam | 5" | 127 mm | k = 0.024 Btu/(hr·ft·°F)\
λ = 0.041 W/(m·K) | R-20 (RSI-3.5) |
| Vapor retarder | Self-adhered membrane (Class II) | - | - | - | - |
| Roof deck | Concrete deck | 6" | 152 mm | k = 0.90 Btu/(hr·ft·°F)\
λ = 1.56 W/(m·K) | R-0.75 (RSI-0.13) |
| Structure | Concrete structure | Variable | Variable | - | - |
| Interior | Exposed concrete or ceiling | - | - | - | - |
**Total Assembly: R-22.8 hr·ft²·°F/Btu (RSI-4.0 m²·K/W)**
**Notes:** Ballast holds the membrane down mechanically instead of adhesive. Makes repairs interesting since you're moving rocks around first. The thermal mass of the concrete deck helps with temperature swings.
***
### Roof Type 6: Standing Seam Metal Roof
**Commercial or residential metal roofing system**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| --------------- | --------------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | -------------------- |
| Exterior | Standing seam metal panels | 24 ga | 0.61 mm | k = 314 Btu/(hr·ft·°F)\
λ = 543.5 W/(m·K) | Negligible |
| Underlayment | Synthetic roof underlayment (Class III) | - | - | - | - |
| Sheathing | OSB or plywood | 5/8" | 16 mm | k = 0.077 Btu/(hr·ft·°F)\
λ = 0.133 W/(m·K) | R-0.75 (RSI-0.13) |
| **Ventilation** | **Air space (vented)** | **1-1/2"** | **38 mm** | **-** | **R-1.2 (RSI-0.21)** |
| Structure | Rafters (24" OC) | 9-1/2" (2x10) | 241 mm | k = 0.080 Btu/(hr·ft·°F)\
λ = 0.138 W/(m·K) | R-11.9 (RSI-2.09) |
| Insulation | Closed-cell spray foam | 7-1/2" | 190 mm | k = 0.016 Btu/(hr·ft·°F)\
λ = 0.028 W/(m·K) | R-45 (RSI-7.9) |
| Air barrier | Spray foam acts as air barrier | - | - | - | - |
| Interior | Gypsum drywall | 1/2" | 13 mm | k = 0.096 Btu/(hr·ft·°F)\
λ = 0.166 W/(m·K) | R-0.45 (RSI-0.08) |
**Total Assembly: R-47 hr·ft²·°F/Btu (RSI-8.3 m²·K/W)**
**Notes:** Metal conducts heat like nobody's business, so the ventilated air space above the sheathing prevents the roof from turning into a radiator. Without it, you're basically heating the neighborhood in summer.
***
### Roof Type 7: Green Roof (Extensive)
**Vegetated roof assembly**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| ------------------- | -------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | ------------------ |
| Vegetation | Sedum or hardy plants | 3-6" | 75-150 mm | Variable | Variable |
| Growing medium | Engineered soil mix | 4" | 100 mm | k = 0.25 Btu/(hr·ft·°F)\
λ = 0.43 W/(m·K) | R-16 (RSI-2.8) |
| Filter fabric | Geotextile | - | - | - | - |
| Drainage layer | Drainage mat | 1" | 25 mm | - | R-1.0 (RSI-0.18) |
| Waterproof membrane | EPDM or TPO (root-resistant) | 60 mil | 1.5 mm | k = 0.13 Btu/(hr·ft·°F)\
λ = 0.225 W/(m·K) | Negligible |
| Protection layer | Protection board | 1/4" | 6 mm | - | - |
| Insulation | Polyiso rigid foam | 3" | 75 mm | k = 0.014 Btu/(hr·ft·°F)\
λ = 0.024 W/(m·K) | R-18 (RSI-3.2) |
| Vapor retarder | Self-adhered membrane (Class II) | - | - | - | - |
| Roof deck | Concrete deck | 8" | 200 mm | k = 0.90 Btu/(hr·ft·°F)\
λ = 1.56 W/(m·K) | R-1.0 (RSI-0.18) |
**Total Assembly: R-36 hr·ft²·°F/Btu (RSI-6.3 m²·K/W)**
**Notes:** The growing medium provides thermal mass and variable R-value depending on moisture content. Wet soil insulates poorly but provides evaporative cooling. Your structural engineer will want to know about the saturated weight, which is considerable.
***
### Roof Type 8: SIP Roof Panel
**Structural insulated panel roof system**
| Layer | Material | Imperial Thickness | Metric Thickness | Thermal Conductivity | Thermal Resistance |
| ------------ | --------------------------------------- | ------------------ | ---------------- | ---------------------------------------------- | ------------------ |
| Exterior | Asphalt shingles or metal | 1/8" | 3 mm | Variable | Negligible |
| Underlayment | Synthetic roof underlayment (Class III) | - | - | - | - |
| Outer facing | OSB sheathing | 7/16" | 11 mm | k = 0.077 Btu/(hr·ft·°F)\
λ = 0.133 W/(m·K) | R-0.5 (RSI-0.09) |
| Core | EPS foam insulation | 10-1/4" | 260 mm | k = 0.024 Btu/(hr·ft·°F)\
λ = 0.041 W/(m·K) | R-41 (RSI-7.2) |
| Inner facing | OSB sheathing | 7/16" | 11 mm | k = 0.077 Btu/(hr·ft·°F)\
λ = 0.133 W/(m·K) | R-0.5 (RSI-0.09) |
| Interior | Gypsum drywall or exposed | 1/2" | 13 mm | k = 0.096 Btu/(hr·ft·°F)\
λ = 0.166 W/(m·K) | R-0.45 (RSI-0.08) |
**Total Panel: R-42.5 hr·ft²·°F/Btu (RSI-7.5 m²·K/W)**
**Notes:** Factory-built means quality control is better than field assembly. The panel itself is the structure, so no thermal bridging through rafters. Ridge and valley details require careful engineering because you can't just slap blocking in there.