Cox Roofing & Restoration · St. Louis
Roof System Infographics
Complete technical breakdown of every roof system we install — layers, specs, ASTM standards, IRC codes, and St. Louis City & County requirements.
01
Residential & Light Commercial
Asphalt Shingle
Roofing System
The most widely installed roof system in St. Louis — and the most frequently damaged in Missouri hail storms. Modern architectural shingles are engineered systems, not just "shingles."
30–50
Year Lifespan
Architectural (Laminated) Shingles
Two fused layers create dimensional shadow lines that mimic wood shake. Heavier, more impact-resistant, and longer-lasting than 3-tab.
Key Product Specifications
Base Mat
Fiberglass
Continuous mat; provides tensile & tear strength
Weight
235–350 lb/sq
Heavier = better wind & hail resistance
Min. Slope
2:12 (IRC)
4:12+ preferred in STL freeze-thaw climate
Wind Rating
Class H
ASTM D7158 — up to 150 mph; STL County req.
Impact Resist.
Class 4
UL 2218 — highest rating; insurer preferred
Fire Rating
Class A
UL 790 / ASTM E108 — req. STL City fire zones
Fastening
4 Nails Min.
6 nails in high-wind zones per IRC R905.2.6
Headlap
2" Min. (IRC)
Overlap of each course over the course below
⬇ Assembly Layers — Top to Bottom
ASTM · IRC · STL Code Reference1
Architectural / 3-Tab Shingles
Fiberglass mat + asphalt + ceramic granules. Top layer — provides UV protection and aesthetics. NOT the waterproof layer alone — system below does that.
ASTM D3462
Fiberglass asphalt shingle standard
2
Starter Strip Course
Sealed starter along eaves provides first-course wind bond. Required per IRC R905.2 — often skipped by inferior contractors.
IRC R905.2.2
Starter strip installation requirement
3
Ice & Water Shield (Eaves + Valleys)
Self-adhering modified bitumen membrane. Min. 24" inside wall line at eaves. All valleys per IRC R905.2.8.2. Critical for STL freeze-thaw ice dam protection.
ASTM D1970 / IRC R905.2.7
Ice dam protection — both jurisdictions
4
Synthetic Underlayment
ASTM D4869 synthetic or D226 Type I felt over entire deck. Two layers required on slopes 2:12–4:12. Slip-resistant surface for installer safety.
ASTM D226 / D4869
IRC R905.2.3 underlayment standard
5
OSB / Plywood Sheathing
Min. 7/16" APA-rated OSB or 15/32" plywood. H-clips for spans over 24". Edge supported. Nailed per IRC nail schedule for wind zone.
APA / IRC R803.2
Structural panel sheathing standard
6
Roof Framing (Rafters / Trusses)
Engineered or dimensional lumber per IRC R802. Truss: ANSI/TPI 1. STL design loads: 20 psf snow + 115 mph wind per ASCE 7.
IRC R802 / ASCE 7
STL: 20 psf ground snow, 115 mph wind
7
Ridge + Soffit Ventilation
Min. 1:150 ratio (1 sq ft vent / 150 sq ft attic). 50% ridge, 50% soffit. Prevents moisture accumulation, extends shingle life, reduces cooling loads.
IRC R806.2
Both STL City (2018) & County (2015)
8
Galvanized Drip Edge Flashing
Min. 26-gauge galvanized (ASTM A653) or aluminum. At eaves before underlayment; at rakes over underlayment. Directs water into gutters.
ASTM A653 / IRC R905.2.8.5
Metal drip edge flashing standard
St. Louis CountyIRC 2015 · Ch. 1116
IRC 2015 R905.2 governs all asphalt shingle installation
ASTM D7158 Class H or D3161 Class F wind resistance required
Ice & water shield mandatory at eaves and all valleys
Permits required for all full replacements; all municipalities
Class A fire rating required in most residential zones
St. Louis CityIRC 2018 · Ord. 70795
IRC 2018 R905.2 — adopted via Ordinance 70795 (08-01-18)
IFC 2018 (Ord. 70796) — Class A fire rated shingles required city-wide
IECC 2018 (Ord. 70799) — R-38 min. attic insulation required
Permits required — Building Division; inspections mandatory
Historic districts (CWE, Soulard, etc.) — SLDC review may apply
✓ Advantages
Lowest installed cost of any major roof system
Wide availability of contractors and materials
Class 4 (UL 2218) impact-resistant options qualify for insurance discounts
Easy to repair — individual shingles replaceable
Wide color and style selection; mimics wood shake or slate
✗ Limitations
Most susceptible to hail damage of any major roof system
Granule loss from hail may not be visible from ground — requires professional inspection
Shortest lifespan of common systems (30–50 yr vs. 50–100+ for metal/tile)
Algae and moss growth common in humid St. Louis summers without copper granules
Asphalt Shingle Inspection
Storm damage, granule loss, curling, nail pops — we document everything for your claim