What Does Ohio Building Code Require Under a New Roof? Ice Barrier, Underlayment, and Ventilation Explained

Short answer: On a new shingle roof, the Residential Code of Ohio requires three main things. The first is an ice barrier at every eave, because Ohio designates every jurisdiction in the state as having a history of ice-dam damage. The second is labeled, code-compliant underlayment over the rest of the deck, doubled on low slopes. The third is attic ventilation of at least 1/150 of the vented space, or 1/300 when the vents are balanced between high and low. Flashing at walls, chimneys, and valleys is required too, and manufacturer instructions carry the force of code.

By Shawn Stypa, Owner, Pring Roofing LLC | Cleveland, Ohio | Updated October 2026

For one-, two-, and three-family homes, the rulebook is the Residential Code of Ohio (RCO). It is based on the 2018 International Residential Code (IRC) with Ohio amendments. Roofing is in Chapter 9 (Ohio Admin. Code 4101:8-9-01) and attic ventilation is in Section 806 of Chapter 8 (Ohio Admin. Code 4101:8-8-01). Both have been in effect since July 1, 2019.

Two points matter for homeowners:

• The code applies to reroofing, not just new houses. RCO 908.1 says that materials and methods used to recover or replace an existing roof must meet Chapter 9. If you are weighing new shingles over old ones, see our guide: Can You Put a New Roof Over an Old One in Ohio?
• Manufacturer instructions are part of the requirement. RCO 904.1 and 905.1 require roof coverings to be applied according to this chapter and the manufacturer's installation instructions.

2026 code review status: The Ohio Board of Building Standards is running its five-year review of the RCO (Amendments Group 107). In the August 2026 proposal sent out for stakeholder comment, Chapter 8 and Chapter 9 are listed as "No change." The statewide ice-damming designation is also kept, and the code stays based on the 2018 IRC. Proposed rules can still change before adoption, and no effective date had been announced as of this writing. Your local building department always has the final word.

Yes, everywhere in Ohio. RCO 905.1.2 requires an ice barrier in areas with a history of ice forming at the eaves, as designated in Table R301.2(1). Footnote h of that table states that all jurisdictions in Ohio have a history of local damage from ice damming. So whether you live in Lakewood, Avon Lake, Medina, or Mentor, the requirement applies.

The rule covers asphalt shingles, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shingles, and wood shakes.

Either of these, used in place of normal underlayment in that zone:

• A self-adhering polymer-modified bitumen sheet, the product most people call "ice and water shield," or
• At least two layers of underlayment cemented together.

• From the lowest edges of all roof surfaces to at least 24 inches inside the exterior wall line. The 24 inches is measured along the slope of the roof, starting where the outside face of the wall would meet the roof deck.
• On roofs with a slope of 8:12 or steeper, it must also reach at least 36 inches up the slope from the eave edge.

That means the deeper your overhang, the farther up the roof the ice barrier has to run. On homes with wide eaves, a single course of membrane may not reach the 24-inch line, so ask how many courses your estimate includes.

Exceptions: detached accessory structures, such as a detached garage or shed, and roof sections that end at a vertical wall over unconditioned space.

Why ice dams form, and how insulation and air sealing prevent them, is a separate topic. See our ice dam prevention guide for Cleveland homes. This article covers what the code requires to be installed.

Above the ice barrier, the deck still needs underlayment that meets RCO 905.1.1 and its three tables.

For asphalt shingles in Ohio's wind zone (under 140 mph ultimate design wind speed), Table 905.1.1(1) allows ASTM D226 Type I, ASTM D4869 Types I to IV, or ASTM D6757 underlayment. The material must bear a label showing that standard. Unlabeled rolls do not meet code.

Table 905.1.1(2) sets the method for asphalt shingles:

The table also says that wrinkles or distortions in the underlayment must not interfere with the shingles' ability to seal. RCO 905.1.1 allows alternatives too, including full-deck self-adhering membrane installed per both manufacturers' instructions.

This is one place where Ohio differs from the model code. The 2018 IRC, Section R905.2.8.5, requires drip edge at eaves and rakes of shingle roofs. Ohio replaced that section. RCO 905.2.8.5 now reads only: "Refer to Sections 903.1 and 905.1," which point back to the manufacturer's installation instructions.

In practice, check what your shingle manufacturer requires. For example, Owens Corning's Preferred Protection Limited Lifetime Warranty requires that new metal flashing and drip edge be installed for the roof to qualify. Pring Roofing installs Owens Corning systems as an Owens Corning Preferred Contractor.

• Wherever the roof meets a wall, changes slope or direction, or has an opening (RCO 903.2.1). Metal flashing must be corrosion-resistant and at least 0.019 inch thick (No. 26 galvanized).
• Sidewalls: step or continuous base flashing at least 4 inches high and 4 inches wide, tucked under the siding (RCO 905.2.8.3).
• Chimneys and penetrations wider than 30 inches: a cricket or saddle on the uphill side (RCO 903.2.2).
• Valleys: an approved valley lining installed before the shingles. Open metal valleys must be at least 24 inches wide (RCO 905.2.8.2).
• Vent pipes, front walls, and chimneys: flashed per the shingle manufacturer's printed instructions (RCO 905.2.8.4).

The code also sets nail requirements. Fasteners must be corrosion-resistant roofing nails, at least 12-gauge with a 3/8-inch head, penetrating at least 3/4 inch into the sheathing or through it (RCO 905.2.5). Each strip shingle needs at least four nails, or more if the manufacturer requires it (RCO 905.2.6).

RCO 806 applies to enclosed attics and enclosed rafter spaces. That includes the sloped ceilings in many story-and-a-half and Cape Cod-style homes around Greater Cleveland.

• Cross ventilation is required for each separate space. Openings must be protected against rain, snow, and animals, with screening between 1/16 and 1/4 inch (RCO 806.1).
• Minimum net free vent area: 1/150 of the vented space (RCO 806.2).
• Exception, 1/300: allowed when 40 to 50 percent of the required vent area is in the upper part of the space, within 3 feet of the ridge measured vertically, and the rest is in the bottom third, typically soffit vents.
• Keep at least 1 inch of air space between insulation and roof sheathing at the vents (RCO 806.3).
• Unvented attics are allowed only when the specific conditions of RCO 806.5 are met.

Example: a 1,500 sq ft attic needs 10 sq ft of net free area at 1/150, or 5 sq ft if the balanced 1/300 exception applies.

Ventilation affects warranties too. Owens Corning's Preferred Protection warranty requires installation over a ventilated deck and excludes damage caused by improper or inadequate ventilation.

Use this checklist when you compare quotes from roofers in Cuyahoga, Lorain, Medina, or Lake counties:

1. 1Ice barrier at all eaves, to at least 24 inches inside the wall line, and to 36 inches on 8:12 or steeper slopes.
2. 2Underlayment brand and ASTM standard, with double coverage on any 2:12 to 4:12 sections.
3. 3Drip edge and new flashing, or a written explanation of why existing metal is being reused.
4. 4Ventilation plan: the intake and exhaust vent types and whether the net free area meets 1/150 or the balanced 1/300.
5. 5Cricket behind any chimney wider than 30 inches.
6. 6Which manufacturer warranty you will receive, and what it requires.

The figures below are general industry estimates from HomeGuide's 2026 roof replacement cost guide, not Pring Roofing pricing:

• Roofing underlayment: about $0.10 to $0.80 per square foot, depending on material.
• Drip edge: about $1.50 to $3.00 per linear foot installed.
• Roof vent installation: about $200 to $700.

Your actual cost depends on roof size, slope, eave depth, and existing ventilation. Pring Roofing provides free quotes and inspections. For overall pricing, see our Cleveland roof replacement cost guide.

Yes. RCO 905.1.2 requires an ice barrier on shingle, slate, and wood roofs, and Table R301.2(1), footnote h, designates every Ohio jurisdiction as having a history of ice-dam damage. Detached accessory structures are exempt.

From the lowest roof edge to at least 24 inches inside the exterior wall line, measured along the slope. On roofs 8:12 or steeper, it must also reach at least 36 inches from the eave edge.

Ohio replaced the IRC's drip edge section. RCO 905.2.8.5 refers to the manufacturer's installation instructions instead. Many manufacturers require it, including Owens Corning for its Preferred Protection warranty.

At least 1/150 of the vented space as net free area (RCO 806.2), or 1/300 when 40 to 50 percent of the vent area is within 3 feet of the ridge and the rest is in the bottom third of the space.

Yes, for asphalt shingles on slopes from 2:12 up to 4:12 (RCO 905.2.2 and Table 905.1.1(2)). Asphalt shingles are not permitted below 2:12.

The Board of Building Standards' August 2026 proposal lists Chapters 8 and 9 as "No change" and keeps the statewide ice-damming designation, but the proposed rules had not been adopted as of this writing.

Pring Roofing LLC has provided residential and commercial roofing in Northeast Ohio since 1936, serving mostly Cuyahoga, Lorain, Medina, and Lake counties from 4472 W 160th St, Cleveland, OH 44135.

• Owens Corning Preferred Contractor (residential)
• Elevate (formerly Firestone) Licensed Applicator and Carlisle authorized applicator (commercial)
• Fully insured
• A+ rating with the Better Business Bureau (BBB)
• Free quotes and inspections
• Open 7am to 10pm, every day

Written by Shawn Stypa, Owner, Pring Roofing LLC.

Pring Roofing will inspect your roof and attic, measure your eaves and ventilation, and show you what Ohio code and your shingle manufacturer require. The inspection and quote are free.

Call 216-941-6298, email contact@pringroofing.com, or request your free quote. We're available 7am to 10pm, seven days a week.

• Ohio Admin. Code 4101:8-9-01, Residential Code of Ohio Chapter 9 "Roof Assemblies" (eff. 7/1/2019), Sections 903, 904.1, 905.1, 905.1.1 and Tables 905.1.1(1) to (3), 905.1.2, 905.2.2, 905.2.5, 905.2.6, 905.2.8.2 to 905.2.8.5, 908.1: https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-9-01_eff_7_1_19.pdf
• Ohio Admin. Code 4101:8-8-01, Residential Code of Ohio Chapter 8, Section 806 "Roof Ventilation" (eff. 7/1/2019): https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-8-01_eff_7_1_19.pdf
• Ohio Admin. Code 4101:8-3-01, Table R301.2(1), footnote h: https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-3-01_eff_7_1_19.pdf
• Ohio Board of Building Standards, Proposed OBC, OPC and RCO Rules Amendments (2026): https://com.ohio.gov/divisions-and-programs/industrial-compliance/boards/board-of-building-standards/building-codes-and-interpretations/proposed-obc-opc-and+rco-rules-amendments
• Ohio BBS, Amendments Group 107 Proposed RCO Amendments, August 2026 eNotification: https://dam.assets.ohio.gov/image/upload/com.ohio.gov/DICO/BBS/Rule%20Docs/dico_bbs_RCO-Rules_and_Summary_New_and_Amended_only.pdf
• 2018 International Residential Code, Section R905.2.8.5 Drip Edge (ICC): https://codes.iccsafe.org/content/IRC2018/chapter-9-roof-assemblies
• Owens Corning, Preferred Protection Limited Lifetime Warranty: https://dcpd6wotaa0mb.cloudfront.net/mdms/dms/Roofing/10020609/10020609-Preferred-Protection-Warranty-Legalese.pdf
• HomeGuide, "What's the Average Cost to Tear Off and Replace a Roof? (2026)": https://homeguide.com/costs/average-cost-to-tear-off-and-replace-roof