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Building Codes 201 – Residential Roofing

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The course “Building Codes 201 – Residential Roofing” is designed to enhance an adjuster’s knowledge, understanding, and professional competence in the handling of residential roofing losses. The module is presented by Leonard Murphy, Vice President and Chair of the Building Codes Department for the Property & Liability Resource Bureau.

This course teaches insurance professionals to research residential codes for information commonly needed when evaluating residential roofing claims. Insurance professionals are often provided options in estimating software or in contractor estimates concerning sheathing, underlayment, ice barriers, drip edge, and ventilation. Using frequently asked questions, the PLRB instructor walks the student step by step through the essential provisions of the code and shows where the resources to complete necessary research can be found for free on the internet that will assist in decision making. It is recommended that PLRB’s Buildings Codes 101 be taken as a prerequisite to this course.

After completing this course, the viewer will be able to:

locate free codes online; describe the difference between the IBC and IRC when trying to determine which applies to given facts; explain the importance of IRC editions, adoption, and amendments for research purposes; describe where roofing requirements are found in the IRC; list the three primary types of roof sheathing; identify the proper grade of plywood or OSB needed for roof sheathing; determine the proper code compliant panel span rating for a given rafter span; explain the significance of panel nominal thicknesses; distinguish between maximum sheathing span and maximum floor span on a rated panel; define live loads, dead loads, and snow loads; find design criteria for snow, wind, and ice barriers for a given location; utilize “ICC code commentary” to support an interpretation of code requirements; explain and locate the Florida 25% rule on reroofing; describe “grandfathering” for existing roofing to the extent that it exists in the codes; describe and calculate the necessary attic roof venting to evaluate the need for additional vents; determine if added venting might be covered as a code upgrade; describe how manufacturer’s instructions can potentially add code requirements and how that might have limits; explain the functions of underlayment; find the code requirements for underlayment weight and necessary layers for a roof; determine if the code requires ice barriers and drip edge; and, determine where complete tear off is required under the code.

The course is designed for insurance professionals and vendors working in the areas of residential property adjustment.

What CE Credit is available?

Note: To qualify for credit, you must submit completion (including a passed final exam if required) within five days of completing the last quiz. No partial credits will be awarded.

State:
Adjuster General CE Hours:
Adjuster Ethics CE Hours:
Attorney General CLE Hours:
State's Course ID:
NH 2.0 482058
TX (classroom equivalent) 1.0 108882
NC 2.0 207250
FL * ( Provider Number: 364169 ) 2.0 - Optional 1198946
IL 2.0 546253
WY 2.0 28065
OK 2.0 1028593

* This course has been approved by the Florida Department of Financial Services for insurance continuing education credit.

Course Content

Introduction to Residential Roofing Codes
Expand
Lesson Content

1) Course Overview
2) IBC v. IRC, which controls?
3) IRC Editions
4) Finding Roofing Provisions in the IRC
a. Free access to codes
b. Chapter 3 – Design and Wind
c. Chapter 5 – Allowable spans for sheathing
d. Chapter 8 – Sheathing grade and ventilation
e. Chapter 9 – Roof coverings
5) Recap

Introduction to Roof Sheathing
Expand
Lesson Content

1) Introduction
2) Types
3) Intro to Exposure Ratings for Elements
4) Intro to Exposure Ratings in IRC
5) Understanding Standards Referenced in the Codes
6) Product Standards 1 and 2
7) Identifying APA and TECO Grade and Bond Classifications
8) Intro to Panel Thickness
9) Recap

Roof Sheathing Span and Thickness
Expand
Lesson Content

1) Introduction
2) Span Table
3) Sheathing Edge Support for Span Strength
4) Load Caveat
5) Nominal Thickness Explained
6) Floor Sheathing as Roof Sheathing
7) Load and Roof Sheathing
a. Definitions in Chapter 2
b. Design Criteria including local criteria Table R301.2(1)
c. Downers Grove Example
8) Recap

Roof Sheathing Load
Expand
Lesson Content

1) Design Criteria – Snow Map
2) Load Design Code Specifications
3) Downers Grove Allowable Span Example
4) Lumber Sheathing Dimension – Common Error
5) Existing Sheathing Example Scenario
6) Potential Problem Proving an Interpretation
7) Florida 25% Reroofing Rule
8) Recap

Manufacturers’ Instructions and Required Venting
Expand
Lesson Content

1) Outline of documents reviewed
2) Manufacturers’ Installation Instructions
3) Attic Roof Venting Coverage
4) Attic Roof Venting Calculations
a. 1/300 calculations
b. 1/150 method (double amount)
c. Free Ventilation Calculators
d. Code Language
e. Finding Coverage
f. History of vent requirement
5) Recap

Roof Underlayment, Ice Barriers, Drip Edge, Tear Off
Expand
Lesson Content

1) Underlayment Importance
2) Underlayment Code Requirement
3) Ice Barrier
a. Explained
b. Unheated porch
c. Steep slope roof
d. Detached unheated building exception
e. History
4) Drip Edge
5) Reroofing and Code Compliance
6) Closing
7) Recap

Get CE Credit or Certificate of Completion.

Submit within 5 days to get CE Credit or Certificate of Completion.

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Building Codes

Does Kaysville, Utah, Residential Building Code Require Ice Barrier Underlayment When Replacing a Roof?

June 26, 2024 By Dan Hartweg QUESTION: For a roofing project in Kaysville, Utah, does the residential building code require ice barrier underlayment? RESPONSE: Yes. The 2021 Utah State Residential Code (USRC) does not require ice barrier underlayment unless there is a history of ice forming along the eaves causing a backup of water, which is left to local jurisdictions to determine and adopt the requirement. 2021 USRC § R905.1.2. Utah did not complete Table R301.2, “Ice Barrier Underlayment Required” column, leaving it to local jurisdictions to complete the table. 2021 USRC Table R301.2. While the Kaysville City Code does not contain any amendments to Table 301.2, according to the Kaysville City Community Development website, ice barrier underlayment is required.  FACTS: Roof repairs at a private residence located in Unincorporated, West Jordan, Utah. DISCUSSION: Utah adopted the 2021 International Residential Code (IRC), including Appendices AE and AQ, with amendments, as the uniform statewide residential code known as the 2021 Utah State Residential Code (USRC) and is part of the mandatory statewide building code, the State Construction Code (SCC). Utah Code § 15A-2-101. (Adoption of SCC); Utah Code §§ 15A-2-103(b), (d), and (m) (adoption); Utah Code §§ 15A-3-101 through 206 (IRC amendments); Utah Code §§ 15A-4-201 through 207 (IRC local amendments); 2021 USRC (ICC page).  The State and its political subdivisions are required to follow the SCC. Utah Code § 15A-1-204(1)(a). The Division administers the SCC, but it is not within the Division's responsibility to enforce it, the responsibility for inspections and enforcement under the SCC fall on the compliance agency. Utah Code § 15A-1-205 (Division duties); Utah Code § 15A-1-207(1) (compliance agency with jurisdiction over project shall inspect and enforce SCC). A compliance agency is defined as an agency of the State or any of its political subdivisions which issues permits for construction regulated under the SCC. Utah Code § 15A-1-202(6). The compliance agency must follow the Division’s established standardized permit system, may charge a fee but must impose a 1% surcharge to help fund Division education efforts, and must promptly review plans and inspect properties. Utah Code § 15A-1-209 (building permit requirements and surcharge); Utah Code § 10-6-160 (municipality may charge fee and must review plans and inspect properties promptly); U.A.C. R156-15A-220 (standardized permits). A search of the subject property on the PLRB address search page indicates that it is located within the City of Kaysville, Utah.  2021 USRC Reroofing Section R908 of the 2021 USRC on Reroofing requires that recovering or replacing an existing roof must comply with the materials and methods outlined for new roofs: 2021 USRC § R908.1. Therefore, the provisions concerning ice barrier underlayment and drip edges in Chapter 9 must be considered.  ICE BARRIER UNDERLAYMENT Ice barrier underlayment is required under Section R905.1.2 where there is a history of ice forming along eaves causing a backup of water as designated in local amendments in Table R301.2: 2021 USRC § R905.1.2.  Utah did not complete Table R301.2 as follows, in relevant part: 2021 USRC Table R301.2. Because no amendment to IRC Table R301.2(1) was made by the legislature, the need for ice barrier underlayment is left to local jurisdictions. Utah Code §§ 15A-3-101 through 206; 2021 USRC Table R301.2. Kaysville City adopted the current version of the International Residential Code adopted by the State of Utah. Kaysville City Code § 18-2-2. The City did not adopt any amendments to Table 301.2. Id., see also, Kaysville City Code Title 18, Chapter 3. However, according to the City’s website, ice barrier underlayment is required. Kaysville City, Community Development, Roofing Requirements.  DISCUSSION: Utah adopted the 2021 International Residential Code (IRC), as amended, as the 2021 Utah State Residential Code (USRC) and part of the 2021 Utah State Construction Code, a uniform statewide code. The state did not complete Table R301.2, leaving the decision to require ice barrier underlayment up to local jurisdictions where there has been a history of ice forming along eaves causing a backup of water. While the Kaysville City Code does not contain an amendment to Table R301.2, according to the Kaysville City Community Development website, ice barrier underlayment is required.

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Building Codes

Does San Antonio, Texas, Residential Building Code Require a Drip Edge When Replacing a Roof?

QUESTION: Does San Antonio, Texas, residential building code require a drip edge shield when reroofing? RESPONSE: Yes. The City of San Antonio, Texas adopted the 2021 International Residential Code (IRC), with amendments as the residential building code for the city. While the subject property is located in unincorporated Bexar County, the area is within the extraterritorial jurisdiction (ETJ) of San Antonio and the code for the City applies. When reroofing a residential structure, Chapter 9 of the IRC requires that the materials and methods outlined for new roofs be followed. Specifically, Section R905.2.8.5 of the IRC requires drip edge be installed at eaves and rake edges of shingle roofs.  FACTS: Roof repairs at a private residence located at in San Antonio, Bexar County, Texas. DISCUSSION: Texas adopted the 2012 IRC with amendments as the statewide code for incorporated cities and gave these cities authority to strengthen, weaken, or adopt newer editions of the IRC. Tex. Loc. Gov't Code § 214.212. For counties, Texas adopted the 2006 IRC as the statewide minimum residential code for counties that opt in by resolution and only for new residential construction in unincorporated areas not within the extraterritorial jurisdiction of a city with an adopted code or where the county seat adopted a different version of the IRC, which would apply over the 2006 IRC. Texas Local Gov’t Code § 233.152 and § 233.153. Incorporated cities have the authority to adopt amendments and procedures for the administration and enforcement of the state-adopted 2012 IRC and IBC. Tex. Loc. Gov't Code § 214.212, § 214.216, and Tex. Att’y Gen. Op. GA-0297 (2005) or pdf version (accessed 9/26/2023). The city amendments may strengthen or weaken the code requirements. Id. In addition, cities have the authority to “consider amendments made by the International Code Council,” which presumptively means adopt newer editions of the IRC and IBC. Tex. Loc. Gov't Code § 214.212, § 214.216, and § 214.217 (cities with population over 100,000 may consider the adoption of a national model code). Counties have the authority to opt in to regulate new construction of residential homes. Texas Local Gov’t Code. § 233.152 and § 233.153. Texas designates certain unincorporated areas contiguous to the corporate boundaries of a city as the extraterritorial jurisdiction of that city, contingent upon the number of inhabitants of the city, ranging from half a mile (fewer than 5,000 in habitants) to five miles (100,000 or more inhabitants). Tex. Loc. Gov’t Code § 42.021. Texas recognizes three types of cities: home-rule, general-law, and special-law. Forwood v. City of Taylor, 147 Tex. 161, 165, 214 S.W.2d 282, 285 (1948). Home-rule city powers are derived from the Texas Constitution and they have the full power of self-government unless the legislature specifically sets limitations on their power while general-law cities are political subdivisions created by the state and possess only those powers specifically conferred by the legislature. Town of Lakewood Village v. Bizios, 59 Tex. Sup. Ct. J. 1007, 493 S.W.3d 527, 531 (2016). Every Texas city, regardless of type, requires specific legislative authority to enforce its building codes beyond its corporate limits and no such authority exists in the code to allow for city enforcement of its building codes in extraterritorial jurisdictions. Collin County v. City of McKinney, 553 S.W.3d 79, 85 (2018). Therefore, the applicable code for extraterritorial jurisdictions in counties that opt-in to Subchapter F of the Local Government Code is the 2006 IRC for new residential construction, unless the county seat adopted a different version of the IRC, which would apply over the 2006 IRC, or the city is a home rule city and adopted a residential building code for the extrajudicial territory which would control. Texas Local Gov’t Code § 233.152 and § 233.153. Enforcement in extraterritorial jurisdictions is by the county. Tex. Loc. Gov't Code § 233.154.and §233.155. A search of the subject property address on the PLRB address search page indicates that it is located within unincorporated Bexar County, Texas. According to the City of San Antonio, Texas, website, the subject property falls within the Extraterritorial Jurisdiction of the City. City of San Antonio, Extraterritorial Jurisdiction Boundary 2021. The City of San Antonio, Texas adopted the 2021 IRC by reference, Chapters 2 through 10, 12 through 23, Section P2904, Chapter 44, and Appendices J, K and Q, with amendments. City of San Antonio, Texas, Code of Ordinances § 10-36 (Ordinance 2022-11-10-0875, adopted November 10, 2022). The City further provided that any matter within the IRC contrary to any existing ordinances prevails and, to the extent they conflict, existing ordinances were repealed. Id. at § 3.02.102. Accordingly, the provisions of the 2021 IRC control on this issue. 2021 IRC Chapter 9, Roof Coverings Chapter 9 of the 2021 IRC provides the requirements for roof coverings of residential structures. Section R908 of the 2021 IRC covers requirements when reroofing and requires that recovering or replacing an existing roof must comply with the materials and methods outlined for new roofs. 2021 IRC § R908.1. 2021 IRC § R908. More specifically to the instant question, drip edges are discussed in Section R905.2.8.5 of the 2021 IRC: 2021 IRC § R905.2.8.5. CONCLUSION: While the State of Texas adopted the 2012 IRC, the Texas Local Government Code allows local jurisdictions to adopt their own building codes. The City of San Antonio, Texas, adopted the 2021 IRC for residential development in the City. The City of San Antonio’s extraterritorial jurisdiction includes the subject property and requires drip edge be installed at eaves and rake edges of shingle roofs.

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Building Codes

Does Lincoln, Nebraska, Residential Building Code Require Ice Barrier Underlayment When Replacing Roof of Barn With Living Quarters?

July 18, 2024 By Dan Hartweg QUESTION: For a reroofing project in Lincoln, Nebraska, is ice barrier underlayment required by the residential building code for a barn with living quarters? RESPONSE: Depends on the roof covering system. Nebraska adopted the 2018 International Residential Code (IRC) as the state residential code and Lincoln adopted the IRC with amendments. Because the barn contains living quarters, it would likely be considered a dwelling and covered by the IRC. If the roof is replaced by an asphalt shingle system, the City of Lincoln requires ice barrier underlayment. If a metal panel roofing system is installed, the IRC requires underlayment in compliance with the manufacturer’s installation instructions but does not specifically require ice barrier underlayment. Accordingly, consultation of the manufacturer’s instructions is necessary to determine the requirements for metal panel roofing. FACTS: A tornado tore the metal roof off a barn with living quarters located in Lincoln, Nebraska, requiring a roof replacement. DISCUSSION: Nebraska adopted the 2018 International Residential Code (IRC), except section R313 and chapters 25 through 33, as the state residential code and part of the State Building Code established by the Building Construction Act. Neb. Rev. Stat. § 71-6402 (purpose); Neb. Rev. Stat. § 71-6403(1)(b) (adoption); 2018 IRC. Local jurisdictions may enact, administer, and enforce a local building code as long as such county, city or village adopts the State Building Code or adopts a local building or construction code that “generally conforms” with the State Building Code. Neb. Rev. Stat. § 71-6406(1)(a). Whether a local building or construction code is generally conforming or non-conforming is spelled out in subsections 71-6406(2) and (3). Neb. Rev. Stat. § 71-6406(2) and (3). If a local building or construction code is not adopted within two years after an update to the State Building Code, the State Building Code applies except for construction on a farm or for farm purposes. Neb. Rev. Stat. § 71-6404; Neb. Rev. Stat. § 71-6406(1)(b). The City of Lincoln adopted the 2018 IRC, as amended. Lincoln Municipal Code § 20.12.010. The City’s amendments to the 2018 IRC may be found in Chapter 12-20 of the Lincoln Municipal Code, known as the Lincoln Residential Building Code. Lincoln Municipal Code, Chapter 12-20. The IRC defines “Dwelling” as “Any building that contains one or two dwelling units used, intended, or designed to be built, used, rented, leased, let or hired out to be occupied, or that are occupied for living purposes.” 2018 IRC § 202. Accordingly, the barn would fall under this definition and the IRC would be applicable to the proposed reroofing project. Chapter 9 of the 2018 IRC covers roof assemblies and reroofing. 2018 IRC Chapter 9. Section R908 specifically covers reroofing and requires that work recovering or replacing an existing roof covering comply with the requirements of Chapter 9. 2018 IRC § R908.1. Section R905.2 of the 2018 IRC covers asphalt shingle roof systems while Section R905.10 covers metal roof panel assemblies. 2018 IRC § R905.2 and § R905.10. For both metal roof panel and asphalt shingle systems, the IRC requires that the underlayment provisions of Section R905.1.1 be followed. 2018 IRC § R905.1.1. Section R905.1.2 specifically covers ice barrier underlayment, which is required “for asphalt shingles, metal roof shingles, mineral surfaced roll roofing, slate and slate-type shingles, wood shingles and wood shakes” when a local jurisdiction completes Table R301.2(1). 2018 IRC § R905.1.2. The City of Lincoln amended Table R301.2(1) and indicated that “Yes” ice barrier underlayment is required. Lincoln Municipal Code § 20.12.140. This is also confirmed by the City of Lincoln Department of Building and Safety Reroofing Policy, which, citing Section R905.1.2, requires “ice barrier...for all spaces.” See, https://www.lincoln.ne.gov/City/Departments/Building-Safety/Residential-Charts-and-Diagrams/Re-Roof-Policy. The language of Section R905.1.2 does not include metal panel roofing systems and Section R905.10 simply cites to Section R905.1.1 for guidance on underlayment requirements. 2018 IRC § R905.10. Similarly, Table R905.1.1(1), Underlayment Types, also refers to Manufacturer’s Instructions for metal panel roofing systems. 2018 IRC Table R905.1.1(1). Accordingly, the manufacturer’s instructions must be considered for metal panel roofing systems and underlayment requirements. CONCLUSION: Nebraska adopted the 2018 International Residential Code (IRC) as the state residential code and Lincoln adopted the IRC with amendments. Because the barn contains living quarters, it would likely be considered a dwelling and covered by the IRC. If the roof is replaced by an asphalt shingle system, the IRC, and the City, require ice barrier underlayment. If the roof is replaced by a metal panel roof system, there is no requirement for ice barrier underlayment in the IRC, but the IRC does require compliance with the manufacturer’s installation instructions, so they must be considered to determine what underlayment is required.

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Building Codes

Sheathing Thickness Requirements for Re-Roofing in Troy, OH

July 19, 2024 By Dan Hartweg QUESTION: For reroofing a private residence located in Troy, Miami County, Ohio, with a rafter span of 24 inches, what sheathing thickness is required? RESPONSE: The existing sheathing should be fine, depending on the facts. The roofer should be able to provide the necessary information outlined below. Is there edge support on the current panel sheathing (e.g. tongue and groove edges or H-Clips) (See TECO-Tech Tips-Wood Structural Panel Edge Clips (H-clips))? Edge clips can make thinner panels acceptable for wider spans. What is the APA span rating stamped on the sheathing? This could be visible in the attic. Even if not to code now, Section 908 of the 2019 Residential Code of Ohio for One-, Two-, and Three-Family Dwellings (RCO) does not require remediating sheathing due to thickness, so if the sheathing was to code at the time of construction, it need not be replaced per code under a legacy exception. This is also supported by the Miami County Department of Development Roof Covering Policy that allows existing deck sheathing to remain in place if it is structurally sound. Lastly, if some of the sheathing is damaged or compromised, small repairs can usually be done without triggering an upgrade, and if a significant portion of the sheathing is damaged, then it is possible that all the sheathing would have to be replaced up to current code. Local roofing experts and building officials would be helpful in making this determination. The span rating on the sheathing should be checked and, along with the rafter span of 24 inches, applied to 2019 RCO Table 503.2.1.1(1) to determine proper sheathing thickness. In Miami County, Ohio, per code, ⅜” sheathing rated 24/0 could be acceptable with a rafter span as much as 24 inches with edge support, whereas 7/16” sheathing with a 24/16 span rating would be acceptable with or without edge supports. One exception would be if the sheathing was damaged or otherwise unsafe, the building code official might require replacement. FACTS: Reroofing insured's home in unincorporated Troy, Miami County, Ohio. The current roof has approximately 1/4” thick plywood decking with a 24-inch rafter span. DISCUSSION: Ohio adopted the 2018 International Residential Code (IRC), including Chapters 2 through 24, 29, and 44 and no appendices, with amendments, as the Residential Code of Ohio for One-, Two-, and Three-Family Dwellings (RCO), the statewide uniform residential code. Ohio Rev. Code Ann. § 3781.10(A)(1) (authority); Ohio Admin. Code 4101:8-1-01 § 101.1 (adoption); Ohio Admin. Code 4101:8-1 through 4101:8-44 (amendments); 2019 RCO. The Ohio State Building Codes are mandated throughout the state; however, local jurisdictions may adopt additional provisions so long as they are not in conflict with the state code. Ohio Rev. Code § 3781.10(A)(1) (Board of Building Standards enact separate uniform codes for residential and nonresidential buildings). Ohio Rev. Code § 3781.01 (A) – (B) (local jurisdiction may adopt rules not in conflict). To enact an enforceable residential regulation, or in the case of a conflict that requires a variance to protect the health and safety of the people, a local jurisdiction must adopt the residential provision and submit it to the Board of Building Standards for approval. Ohio Rev. Code § 3781.10(A)(2). Ohio Rev. Code § 3781.01 (C). Ohio did not adopt the Appendices to the 2018 IRC, including Appendix J. Ohio Admin. Code 4101:8 et seq. Pursuant to section 102.7, the provisions of section 113 shall control the alteration, repair, addition, maintenance, and change of occupancy of any existing structure. Ohio Admin. Code 4101.8-1-01 §102.7. A search of the subject property on the PLRB Address Search page indicates that it is located within unincorporated Concord Township, Miami County, Georgia. Accordingly, the Miami County code would be relevant in considering this question; however, our search did not identify any local amendments to the RCO. See Miami County Department of Development, Codes that are Enforced. Re-Roofing Provisions Section 908 of the RCO on Reroofing requires that recovering or replacing an existing roof must comply with the materials and methods outlined for new roofs under Chapter 9 of the RCO: “908.1 General. Materials and methods of application used for recovering or replacing an existing roof covering shall comply with the requirements of Chapter 9. Exceptions: Reroofing shall not be required to meet the minimum design slope requirement of one-quarter unit vertical in 12 units horizontal (2-percent slope) in Section 905 for roofs that provide positive roof drainage. For roofs that provide positive drainage, re-covering or replacing an existing roof covering shall not require the secondary (emergency overflow) drains or scuppers of Section 903.4.1 to be added to an existing roof. 908.2 Structural and construction loads. The structural roof components shall be capable of supporting the roof covering system and the material and equipment loads that will be encountered during installation of the roof covering system. 908.3 Roof replacement. Roof replacement shall include the removal of existing layers of roof coverings down to the roof deck. Exception: Where the existing roof assembly includes an ice barrier membrane that is adhered to the roof deck, the existing ice barrier membrane shall be permitted to remain in place and covered with an additional layer of ice barrier membrane in accordance with Section 905. 908.3.1 Roof recover. The installation of a new roof covering over an existing roof covering shall be permitted where any of the following conditions occur: Where the new roof covering is installed in accordance with the roof covering manufacturer’s approved instructions. Complete and separate roofing systems, such as standing-seam metal roof systems, that are designed to transmit the roof loads directly to the building’s structural system and do not rely on existing roofs and roof coverings for support, shall not require the removal of existing roof coverings. Metal panel, metal shingle and concrete and clay tile roof coverings shall be permitted to be installed over existing wood shake roofs where applied in accordance with Section 908.4. The application of a new protective roof coating over an existing protective roof coating, metal roof panel, metal roof shingle, mineral surfaced roll roofing, built-up roof, modified bitumen roofing, thermoset and thermoplastic single-ply roofing and spray polyurethane foam roofing system shall be permitted without tear-off of existing roof coverings. 908.3.1.1 Roof recover not allowed. A roof recover shall not be permitted where any of the following conditions occur: Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing. Where the existing roof covering is slate, clay, cement or asbestos-cement tile. Where the existing roof has two or more applications of any type of roof covering. 908.4 Roof recovering. Where the application of a new roof covering over wood shingle or shake roofs creates a combustible concealed space, the entire existing surface shall be covered with gypsum board, mineral fiber, glass fiber or other approved materials securely fastened in place.” 2019 RCO § 908. Chapter 9 of the RCO covers roof assemblies and applies for both new construction and re-roofing projects as provided above. Roof covering requirements are provided in Section 905, with sheathing asphalt shingle roofs specifically covered in section 905.2.1 and simply requiring “solidly sheathed decks.” 2019 RCO § 905.2.1. This chapter is otherwise silent regarding roof sheathing or requirements that are laid out in Chapters 5 or 8 of the RCO for new construction. The requirement of Section 908.3 to remove all layers down to the deck implies that everything above the deck is within the scope of work. 2019 RCO § 908.3. Section 113 of the RCO covers existing buildings and structures with Section 113.5 providing the requirements for the replacement of systems, components, and materials. 2019 RCO § 113.5. Section 113.5 states, “Replacements of an existing system (egress, fire protection, mechanical, plumbing, etc.) and materials or building components not otherwise provided for in this section, shall conform to that required for new construction to the extent of the alteration. The existing systems, materials, or components shall not be required to comply with all of the requirements of this code for new construction except to the extent that they are affected by the alteration. Replacement of existing systems, materials, or components shall not cause them to become unsafe, hazardous, overloaded, or become less effective than when originally installed, constructed, and/or approved.” Id. These sections all support the conclusion that, as long as the current sheathing provides a solidly sheathed deck, it may remain in place when reroofing the structure. The Miami County Department of Development Roof Covering Policy provides additional support for this analysis, stating that “if the existing sheathing is in structurally sound, it can be used for the new installation.” Miami County Department of Development, Roof Covering Policy. In addition, the policy allows the use of 3/8” sheathing for repairs, indicating that if repair work on sheathing that is not up to current code. Id. However, it follows that, in some instances, the roof deck may become part of the scope of work. This might include examples such as the deck having excessive gaps that do not permit the installation of asphalt shingles, or when there are signs of exposed rot, warping, delamination, or excessive nail holes. In such cases, the scope of work may expand to include work on the deck. The existence of one or more of these issues in the decking may conflict with the asphalt shingle requirement for "solidly sheathed decks" and installing new materials over defective materials such as rot or warping may arguably make the building less safe or effective and thereby conflict with Section 113.5. New Roof Deck/Sheathing Requirements In the event the roof deck needs replacement or the building official deems it to be unsafe, it must comply with the new construction requirements of Section 803 of the RCO. 2019 RCO § 803. Wood structural panel sheathing, such as OSB or plywood that are being applied here, is specifically covered under section 803.2. 2019 RCO § 803.2. Per Section 803.2.1, wood structural panels must comply with Table 503.2.1.1(1) and the requirements therein in determining the required thickness. 2019 RCO § 803.2.1. (Note that this is different than that for wood lumber sheathing provided under Section 803.1 requiring minimum ⅝” thickness. 2019 RCO Table 803.1.) Table 503.2.1.1(1) provides:     2019 RCO Table 503.2.1.1(1). The initial, and key determination to make is what is the span rating of the current sheathing. This rating is a key determination because, based on manufacturing anomalies, the actual thickness of wood structural panels may vary throughout the panel. The span rating is stamped on sheathing and may be visible in the attic. The following is an example of the APA stamp and how to identify this information: Once the panel rating is known, the span between the rafters must be measured and that can be applied to Table R503.2.1.1(1). At this point, the roof and snow loads can be determined to apply to the Table as outlined in Section 301 of the 2019 RCO. . . . . . . . . . . . . According to Figure 301.2(6), the ground snow load for the area is 20 psf and the value to apply to the Load column in Table 503.2.1.1(1). Under Table 503.2.1.1(1), if the sheathing has a span rating of 24/16 the 7/16” sheathing should be appropriate for the 24-inch span rafters. Accordingly, for a reroofing project on a residential dwelling with 7/16” thick sheathing that is in good condition, that sheathing should be allowed to remain as long as it does not cause the building or structure to become unsafe or lower existing levels of health and safety. If there are several or significant areas of deteriorated sheathing or other conditions that create unsafe conditions, consideration of Chapters 5 and 8 of the RCO, which cover sheathing requirements for new construction or replacement, must be undertaken. CONCLUSION: Based on this analysis, as long as the sheathing is structurally sound, it may be maintained. If the sheathing is damaged or otherwise does not provide proper support, it is likely that 7/16” sheathing would be allowed under the RCO for a residential re-roofing project in Blacklick, Ohio. Applying the span rating of the sheathing and the span between the rafters to Table 503.2.1.1(1) of the RCO will provide the answer. One caveat is whether there is damage to the current sheathing that is significant enough to require replacement and application of the RCO as if it were new construction.

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