Ohio Residential Roofing Code: A Homeowner's Reference

Who this is for

This article is a homeowner's reference to the Ohio residential roofing code — what's required, where to verify it, and how local jurisdictions affect what applies to your project. It's the source you can return to when something in another article says "per ORC R905.1.2" and you want to know what that actually means.

Building codes exist to protect homeowners from unsafe construction and to set baseline standards every roof must meet. Most legitimate roofing contractors work to code as a starting point — best practices often exceed code requirements. But knowing what code actually requires helps you spot when a contractor is cutting corners and when a quote excludes something that should be standard.

This article is informational only. Code requirements vary by edition, and local jurisdictions can adopt additional or stricter requirements. Always verify current code with your local building department before beginning any roofing project.

The current Ohio Residential Code

Ohio's residential building code is administered by the Ohio Board of Building Standards (BBS) and adopted under Ohio Administrative Code Chapter 4101:8.

The current edition is the 2019 Residential Code of Ohio (RCO), effective July 1, 2019, based on the 2018 International Residential Code (IRC) with Ohio-specific amendments. The 2019 RCO governs the design, materials, construction, alteration, and repair of one-, two-, and three-family dwellings throughout Ohio.

You can access the full text of the 2019 RCO through:

• ICC Digital Codes (official) — free access through the Ohio bookshelf
• UpCodes (alternative) — easier section-specific navigation
• Ohio Administrative Code (state-hosted) — official rule text

For non-residential buildings (commercial, multifamily over three units, agricultural), the Ohio Building Code (OBC) Chapter 15 governs roof assemblies. Most residential homeowners don't need this — but it applies if your project involves a townhome over three units or a mixed-use property.

Chapter 9: Roof Assemblies (the main chapter)

Chapter 9 of the 2019 RCO governs nearly everything about residential roof construction. It defines a roof assembly as the deck, substrate or thermal barrier, insulation, vapor retarder, and roof covering — meaning the inspector isn't just checking shingles, they're checking the whole stack.

The chapter covers:

• Fire classification (Class A, B, C roof assemblies)
• Wind resistance requirements
• Flashing and drainage requirements
• Underlayment requirements
• Roof covering materials (asphalt shingles, metal panels, single-ply membranes, modified bitumen, etc.)
• Above-deck insulation
• Rooftop-mounted photovoltaic systems
• Reroofing (recovering and replacing existing roofs)

Below are the sections most relevant to residential homeowners.

Roof slope minimums by material (R905)

Section R905 sets minimum slopes for each roofing material. Below this slope, the material is not permitted for new construction:

Practical implications:

• Below 2:12, you cannot use asphalt shingles on new construction — the roof must use a low-slope membrane, standing seam, or another low-slope-rated system
• Between 2:12 and 4:12, asphalt shingles require double underlayment per R905.1.1
• Standing seam metal has the lowest minimum slope of any sloped system (¼:12), making it one of the few options for low-pitch additions and porches

For background on how each roof type works at these slopes, see our guides to how a residential shingle roof works, how a residential metal roof works, and how a residential flat roof works.

Ice barrier requirement (R905.1.2)

Ohio is a designated ice-dam region under RCO Table 301.2(1). This means R905.1.2 mandates ice barrier installation for asphalt shingles, metal roof shingles, mineral-surfaced roll roofing, slate, wood shingles, and wood shakes — statewide, in every Ohio jurisdiction.

The ice barrier requirement:

• Must consist of either two layers of underlayment cemented together OR a self-adhering polymer-modified bitumen sheet (ASTM D1970)
• Must extend from the lowest edge of all roof surfaces to a point not less than 24 inches inside the exterior wall line of the building
• The 24-inch measurement is along the slope of the roof from where the projected outside face of the wall intersects the roof deck
• On roofs with slope 8:12 or greater, the ice barrier must extend 36 inches measured along the roof slope from the eave edge

Exception: Detached accessory structures that contain no conditioned floor area (unheated detached garages, sheds) are exempt.

In practice, quality installers extend ice and water shield beyond the code minimum — into valleys, around skylights and chimneys, around all penetrations. For more on why this matters, see our shingle replacement guide.

Wind resistance requirements (R905.2.4)

R905.2.4 requires asphalt shingles to be tested for wind resistance in accordance with ASTM D7158, and to meet the classification requirements of Table 905.2.4.1 for the appropriate ultimate design wind speed for the project location.

For shingles not within the scope of D7158, ASTM D3161 testing applies.

For Columbus and most of central Ohio, the design wind speed is approximately 115 mph (3-second gust), per ASCE 7 wind maps. This means shingles rated to ASTM D7158 Class G or H, or D3161 Class F, are appropriate for central Ohio.

Most modern architectural shingles sold for residential use meet Class H/Class F ratings out of the box. The label on the shingle wrapper specifies the rating. Always verify the rating matches your local design wind speed before signing a contract.

Important caveat: these ratings are for new, fully-sealed shingles in laboratory conditions. Real-world performance depends on shingle age, seal integrity, slope, orientation, and installation quality. For more on how wind damage actually develops on aging shingles, see our storm damage article.

Shingle fastener requirements (R905.2.5)

R905.2.5 specifies:

• Minimum 4 fasteners per strip shingle (or 2 per individual shingle)
• Fasteners must be galvanized steel, stainless steel, aluminum, or copper roofing nails
• Minimum 12-gauge shank with minimum 3/8-inch-diameter head
• Length must penetrate through the roofing materials and a minimum of 3/4 inch into the roof sheathing (or through the sheathing if thinner)

For roofs at slopes greater than 21:12 (very steep) or in high-wind areas, manufacturers may specify 6 fasteners per shingle.

The 4-nail vs 6-nail decision is often a manufacturer warranty distinction more than a code one — manufacturer specifications can require 6-nail installation for extended warranty coverage in certain wind zones.

Underlayment requirements (R905.1.1)

Table R905.1.1 specifies underlayment standards by roofing material:

• ASTM D226 Type I (#15 felt) or Type II (#30 felt)
• ASTM D4869 (synthetic-equivalent organic felt)
• ASTM D6757 (modified asphalt-saturated felt)
• ASTM D1970 (self-adhering polymer-modified bitumen)

Synthetic underlayments must be installed in accordance with the manufacturer's instructions and meet the applicable ASTM standard.

For asphalt shingle slopes of 2:12 to 4:12 (low slope), double underlayment is required per R905.1.1.

Roof deck requirements (R905.2.1 and Chapter 8)

R905.2.1 requires asphalt shingles to be fastened to solidly sheathed decks. Spaced sheathing (often found on older roofs originally built for wood shingles) is not acceptable for asphalt shingles unless it is first covered with solid sheathing.

Chapter 8 of the RCO governs roof structural framing, rafter and truss requirements, and deck specifications. Wood structural panels must conform to DOC PS 1, DOC PS 2, CSA O437, or CSA O325 and be grade-stamped.

Many local Ohio jurisdictions have additional sheathing requirements — for example, some municipalities specify minimum 5/8-inch roof sheathing for new installations. Verify with your local building department.

Flashing requirements (R903.2)

R903.2 requires flashing at all roof intersections, slope changes, penetrations, and chimney/wall transitions. Where flashing is of metal, it must be corrosion-resistant with a thickness of not less than 0.019 inch (No. 26 gauge galvanized).

Specific flashing requirements include:

• Drip edge — required at eaves and gables of shingle roofs per R905.2.8
• Step flashing at vertical wall intersections
• Valley flashing — must extend at least 11 inches from centerline each way, with sections lapped not less than 4 inches at ends
• Cricket/saddle — required on the ridge side of any chimney or penetration more than 30 inches wide (measured perpendicular to slope)
• Skylight flashing — per skylight manufacturer instructions

For roof slopes of 3:12 and greater, valley flashing requires a 36-inch-wide Type I underlayment running the full length of the valley, in addition to other required underlayment.

In Ohio (where the average January temperature is 25°F or below in much of the state), R905.2.8.2 requires metal valley flashing underlayment to be solid-cemented to the roofing underlayment for slopes less than 7:12, OR a self-adhering polymer-modified bitumen sheet.

Drainage requirements (R903.4)

R903.4 requires that roofs drain. For roofs that don't slope to drain over the roof edges:

• Roof drains must be installed at each low point
• Where parapets or other construction extend above the roof and could trap water, secondary (emergency overflow) drains or scuppers must be installed
• Overflow drains must match the size of primary drains and be located 2 inches above the low point of the roof
• Overflow scuppers must be sized at three times the primary drain area, with minimum 4-inch height, located 2 inches above the low point

Exception for reroofing: Per R908.1, when re-roofing a roof that already provides positive drainage, secondary drains/scuppers are not required to be added. This exception allows older Ohio flat roofs to be reroofed without expensive structural work to add overflow drainage.

Ventilation requirements (R806)

Section R806 of Chapter 8 governs attic ventilation. The requirements:

R806.1 — Cross-ventilation required

Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space.

R806.2 — Minimum vent area

The minimum net free ventilating area must be 1:150 of the area of the vented space (1 square foot of ventilation for every 150 square feet of attic floor area).

Exception: The minimum can be reduced to 1:300 if both of the following are met:

1. A Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling (in Climate Zones 6, 7, and 8 — most of Ohio falls in Climate Zone 4 or 5)
2. Not less than 40% and not more than 50% of the required ventilating area is provided by ventilators located in the upper portion of the attic (within 3 feet of the ridge), with the balance in the bottom one-third

R806.3 — Vent screening

Vent openings must have minimum 1/16-inch and maximum 1/4-inch openings, with corrosion-resistant wire cloth or similar screening required for larger openings.

R806.5 — Unvented attic assemblies

R806.5 allows unvented attic assemblies (often spray-foam insulation against the underside of the roof deck) when specific conditions are met:

1. No interior Class I vapor retarder on the ceiling
2. Specific minimum R-value of air-impermeable insulation on the underside of the roof sheathing
3. Air-impermeable insulation must be in direct contact with the underside of the structural roof sheathing
4. The roof assembly meets specific requirements based on climate zone

This is the basis for most modern flat roof and cathedral ceiling construction in Ohio.

For practical implications of ventilation requirements, see our shingle replacement and flat roof replacement guides.

Reroofing rules (R908)

Section R908 governs recovering or replacing existing roofs.

R908.3 — Recover not permitted

A roof recover (installing a new roof covering over an existing one) is not permitted when any of the following occur:

1. The existing roof or roof covering is water-soaked or has deteriorated to the point that it's not adequate as a base for additional roofing
2. The existing roof covering is slate, clay, cement, or asbestos-cement tile
3. The existing roof has two or more applications of any type of roof covering

This is the source of the often-cited "two-layer maximum" rule in Ohio. If your roof already has two layers, the next replacement must be a full tear-off.

Exceptions to R908.3 (when recover IS allowed)

The code includes specific exceptions:

1. Complete and separate roofing systems — standing-seam metal roof systems that are designed to transmit roof loads directly to the building's structural system (typically on purlins or battens) and do not rely on the existing roof for support are allowed without tear-off
2. Metal panel, metal shingle, and concrete/clay tile roof coverings may be installed over existing wood shake roofs (when wood shakes are present and the manufacturer permits the application)
3. Protective coatings over existing protective coatings or single-ply membranes may be applied without tear-off
4. When applying new roof covering over wood shingle or shake roofs, the entire existing surface must be covered with gypsum board, mineral fiber, glass fiber, or other approved material to eliminate combustible concealed space

R908.1 — Reroofing exceptions for low-slope

When reroofing (not new construction) low-slope roofs:

1. The ¼:12 minimum slope of R905 does not apply to roofs that already provide positive roof drainage
2. Secondary (emergency overflow) drains/scuppers under R903.4.1 do not have to be added to existing roofs that already provide positive drainage

These exceptions are critical for older Ohio flat roofs — they don't have to be rebuilt to current new-construction standards when reroofed.

Photovoltaic (solar) systems on roofs (R902)

R902 addresses building-integrated photovoltaic (BIPV) products and rooftop-mounted PV systems.

• BIPV roof panels: must be tested, listed, and labeled for fire classification per Section 902.1, and listed/labeled per UL 1703
• Rooftop-mounted PV systems: must be tested, listed, and identified with a fire classification per UL 1703 and UL 2703
• BIPV panels: only allowed on roof slopes of 2:12 (17%) or greater

The fire classification of the BIPV product or the rooftop-mounted PV system must comply with the classification required for the building's roof assembly.

Local jurisdictions and permits

Ohio operates under a "home rule" framework — municipalities and counties can add requirements beyond the state code, but they cannot reduce code requirements. The 2019 RCO sets the minimum; local jurisdictions can adopt stricter standards.

Permits

Most Ohio jurisdictions require a permit for residential roof replacement. Some smaller municipalities and unincorporated areas don't, but the safer assumption is that one is required. The contractor typically pulls the permit before work begins. Unpermitted roof replacements can create problems at home sale, and many manufacturer warranties require permitted installation.

Common documentation required for a residential reroofing permit:

• Property address and parcel information
• Description of work scope (tear-off, recover, partial replacement)
• Material specifications (manufacturer, product line, color)
• Contractor information and local registration documentation
• Estimated cost

Permit fees vary by jurisdiction. Many Ohio cities use a base fee plus a per-square or per-square-foot calculation. Verify with your local building department.

Inspections

For permitted work, the local building inspector typically performs an inspection after work is complete. Some jurisdictions also require an in-progress inspection — for example, an inspection of the deck after tear-off but before underlayment goes down.

The inspector verifies the work meets the code requirements outlined above. A failed inspection requires correction and re-inspection before the permit closes. Documentation that a permit was pulled and closed is what protects you if disputes arise later about whether the work was code-compliant.

Contractor licensing in Ohio

This is one of the most-misunderstood parts of Ohio residential roofing.

Ohio does NOT have a statewide roofing license. The Ohio Construction Industry Licensing Board (OCILB) under Ohio Revised Code 4740 licenses commercial contractors in five specialty trades:

1. Electrical
2. Plumbing
3. HVAC
4. Hydronics
5. Refrigeration

Roofing is not on this list. No state-level roofing license exists in Ohio.

Instead, residential roofing contractors are regulated at the county and municipal level. Many cities require local registration, bonding, and proof of insurance before a contractor can legally pull permits.

Major Ohio city requirements

• Columbus — Issues Home Improvement Contractor licenses (Limited or General) through the Department of Building and Zoning Services. General Contractors must furnish a $25,000 bond. Liability insurance minimum $500,000.
• Cincinnati — Requires registration through the City of Cincinnati Permit Center. Requires certificate of liability insurance and workers' compensation. Application fee $131.25.
• Cleveland — Requires contractor registration through the Department of Building and Housing. Requires notarized application, $150 fee, bond form with power-of-attorney, certificate of liability insurance, insurance endorsement.
• Most smaller Ohio municipalities — require local registration of some form before pulling permits

Insurance

While Ohio doesn't require state licensing, most municipalities require contractors to carry:

• General liability insurance — minimum varies by jurisdiction, commonly $500,000 to $1,000,000
• Workers' compensation — required for any contractor with employees in Ohio per the Ohio Bureau of Workers' Compensation

How to verify a contractor in Ohio

Before signing any contract:

1. Contact your local building department and confirm the contractor is registered to perform work in your municipality
2. Request a Certificate of Insurance (COI) showing both general liability and workers' compensation coverage
3. Call the insurance carrier directly using the number listed on the COI (not a number the contractor provides separately) to confirm the policy is currently active
4. Verify workers' comp coverage through the Ohio BWC
5. Check the contractor's BBB rating and online reviews for documented local reputation
6. For commercial work, verify OCILB license at com.ohio.gov
7. For Public Adjuster verification (separate from contractor), verify license through the Ohio Department of Insurance

A contractor who refuses to provide a COI, hesitates when you ask to verify it, or pressures you to sign before completing verification is not meeting the basic standard for legitimate residential roofing work.

For more on choosing a contractor and avoiding storm-chaser scams, see our storm damage guide.

Quick reference: Ohio code section index

When another article cites an Ohio code section, here's what's at each section:

Key takeaways

• Ohio's current code is the 2019 RCO, based on the 2018 IRC, in effect since July 1, 2019
• Ice barrier is required statewide — 24 inches inside the exterior wall line (36 inches on roofs 8:12 or steeper)
• Two-layer maximum on shingle roofs — the third replacement must be a full tear-off
• Standing seam metal can be installed over shingles under specific conditions (R908 exception for load-transmitting systems)
• Attic ventilation is required at 1:150 (or 1:300 with proper vapor retarder and balanced placement)
• Ohio does not have a statewide roofing license — verify locally with your municipality and confirm insurance coverage directly
• Most jurisdictions require permits for residential roof replacement
• Local jurisdictions can require stricter standards than state code, but never less

When in doubt, always verify with your local building department and consult the official code text. The links in this article point to authoritative sources for every claim.

This article is informational and reflects code requirements in effect at time of publication. Code editions update periodically, and local jurisdictions in Ohio may have additional amendments. Always verify current code requirements and contractor licensing with your local building department before beginning any roofing project. This article does not constitute legal advice.