Roofing & Insulation Guide
Roofing & Insulation Guide
California roofs face sun, wind, and seasonal rain. The right roofing system and insulation layer protect your building envelope, cut energy costs, and keep inspectors happy. Here is how to spec it right the first time.
Shingle Selection
Architectural laminated shingles offer better wind resistance and a longer lifespan than three-tab shingles. For most residential projects in California, a Class A fire-rated architectural shingle is the standard. Always pair shingles with a quality underlayment — 30lb felt is the minimum, but synthetic underlayment is increasingly preferred for its tear resistance.
IRC requires drip edge flashing on all rake and eave edges. It is not optional. Galvanized steel drip edge directs water into gutters and protects fascia boards from rot.
Siding Options
Vinyl Siding
- Low cost, low maintenance
- Wide color selection
- Not fire-rated
- Best for: Budget residential
Fiber Cement (HardiePanel)
- Non-combustible, Class A
- Resists rot, pests, impact
- Heavier, requires specialized cutting
- Best for: High-fire zones, modern builds
Insulation: R-Value by Application
| Location | Recommended R-Value | Product Type |
|---|---|---|
| 2x4 Exterior Walls | R-13 to R-15 | Fiberglass batt, kraft-faced |
| Attic Floor | R-30 to R-38 | Fiberglass batt or blown-in |
| Foundation Walls | R-5 to R-10 | XPS rigid foam board |
| Crawl Space | R-13 | Fiberglass batt with vapor barrier |
Air Sealing and Radiant Barriers
Insulation slows heat transfer, but air leaks bypass it entirely. Seal rim joists, penetrations, and top plates with closed-cell spray foam before installing batt insulation. In hot climates, a reflective radiant barrier on attic rafters can reduce cooling loads by blocking up to 97 percent of radiant heat.
Closed-Cell vs Open-Cell Spray Foam
- Closed-cell: Higher R-value per inch (R-6+), vapor barrier, structural rigidity. Best for rim joists, metal buildings, and exterior applications.
- Open-cell: Lower cost, softer, allows moisture passage. Best for interior wall cavities and sound dampening between floors.
Delivery Notes
Shingles are heavy. A square (100 sq ft) of architectural shingles weighs approximately 240 lbs. Plan your roof loading and staging area before delivery. Western Works delivers shingles, underlayment, and insulation on the same truck to reduce your handling time.