Oklahoma Residential Roofing Codes
Oklahoma residential roofing codes are based on the International Residential Code (IRC) 2018, with state amendments for our climate. Below are the section numbers and local rules that matter most, so you can check that your roofer is doing the job to code.
Why this matters
A roof that ignores these codes is not just a violation. It fails early, leaks, and can void your insurance or your manufacturer warranty. Oklahoma follows the International Residential Code (IRC) 2018 with amendments written for our wind, hail and ice.
Key Oklahoma Modifications
Ice Barriers (Section 905.1.2)
- Must extend 24" inside exterior wall line.
- 36" extension if slope > 67%.
OK Specific: 36" barrier required in all valleys & slope changes.
Drip Edges (Section R905.2.8.5)
Generally required at eaves/rakes, BUT Oklahoma allows an exception if:
- A 1x2 inch shingle mold is used.
- Starter shingles extend 1/4" to 1" beyond fascia.
Roof Decks (Section R905.2.1)
"Solidly Sheathed" is strictly defined as sawn lumber or structural panels with:
- No Gaps
- No Rot
- No Warping
Specific Material Codes:
- Clay/Concrete: R905.3.1
- Metal Tile: R905.4.1
IRC 2018 / OK Amendments
Re-Covering Restrictions
A complete tear-off is mandatory if:
- Existing roof is water-soaked or deteriorated.
- Material is slate, clay, or asbestos-cement.
- Roof has 2+ layers of any material.
Oklahoma Exclusive
The "One Layer" Limit
If the existing roof has one or more layers of asphalt shingles, you cannot add another layer. You must tear off.
Section R905.2
Asphalt Shingle Standards
Slope
Section R905.2.2
Minimum: 2:12
2:12-4:12 requires double underlayment
Underlayment
Section R905.2.3
Mandatory
> 4:12 = 1 Layer
2:12 to 4:12 = 2 Layers
Material
Section R905.2.4
Must comply with ASTM D3462
High wind (>110mph) needs ASTM D7158/D3161
Fasteners
Section R905.2.2
Corrosion-resistant nails only
Min penetration: ¾ inch or through deck
Water Management Essentials
Flashing
Section R903.2
Corrosion-resistant at all intersections.
Crickets
Section R903.2.2
Required for chimneys > 30 inches wide.
Coping
Section R903.3
Non-combustible weather-resistant caps.
Drainage
Section R903.4
Overflow drains required for internal systems.
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