Editor's note: Following is part one of a two-part series addressing building codes. Part two will appear in the January 2018 issue.
Model codes such as those developed by the International Code Council® (ICC) serve as the technical basis for state, county and local adoption of codes that regulate the design, construction and operations of buildings.
ICC, promulgator of the International Building Code® and other related international codes, recently updated and published revised editions of its model codes, known as the "I-Codes," as part of its normal three-year update cycle.
The International Building Code, 2018 edition (IBC 2018) presents the code as it originally was published in 2000; changes reflected in the 2003, 2006, 2009, 2012 and 2015 editions; and further changes approved through ICC's code development process through 2017.
As jurisdictions begin the process of updating their codes, you should be aware of the changes incorporated into the 2018 I-Codes. Following is an overview of some of the more significant roofing-related changes in IBC, the International Energy Conservation Code,® International Fire Code® and International Plumbing Code.®
IBC 2018 applies to all buildings except detached one- and two-family dwellings and multiple single-family dwellings not more than three stories above grade plane.
The most significant roofing-related change is the 2018 edition references ASCE Standard 7-16, "Minimum Design Loads and Associated Criteria for Buildings and Other Structures." The previous edition references ASCE 7-10, "Minimum Design Loads for Buildings and Other Structures."
Referencing ASCE 7-16 (and related changes in IBC 2018's Chapters 15 and 16) is significant for roof assembly design because ASCE 7-16's major revisions include revised basic wind speed maps, changes to and the addition of new pressure coefficients, and revised perimeter and corner zones.
In many cases, roof system designers will find higher field, perimeter and corner uplift pressures for designs per ASCE 7-16 vs. ASCE 7-10. Also, the percentage of roof area within the highest-pressure zones has increased in the updated standard. In other words, wind design for roof assemblies is more complex and, for some projects, design wind pressures will be greater. NRCA recommends roof system designers coordinate with local building code officials and roofing material manufacturers to ensure roof assembly wind design methods are consistent with jurisdictional requirements.
Located in Chapter 2—Definitions, several terms and definitions relevant to roof assemblies have been added or revised: attic; building-integrated photovoltaic roof panel (BIPV roof panel); continuous insulation; repair; roof assembly; roof coating; skylights and sloped glazing; underlayment; vapor retarder class; vegetative roof; windborne debris region; and wind speed. The definitions for these terms generally are consistent with those understood in the roofing industry. In the previous IBC edition, a list of roofing-related terms was included in Chapter 15 with a reference to Chapter 2. The roofing-related term list and reference are absent from IBC 2018.
A majority of IBC 2018's roofing-related requirements appear in Chapter 15—Roof Assemblies and Rooftop Structures.
The exception to Section 1504.1.1—Wind Resistance of Asphalt Shingles has been updated to make clear shingle packaging is required to bear compliance labeling but not the shingles themselves.
Section 1504.2.1.1—Overturning Resistance has been reworded to require concrete and clay roof tiles be tested to determine their wind resistances in accordance with IBC 2018's Chapter 15 and either Southern Building Code Congress International Inc. Standard 11 (SBCCI SSTD 11), "Test Standard for Determining Wind Resistance of Concrete or Clay Roof Tiles," or ASTM C1568, "Standard Test Method for Wind Resistance of Concrete and Clay Roof Tiles (Mechanical Uplift Resistance Method)." Although SBCCI SSTD 11 appeared in the previous version, the reference to ASTM C1568 is new for IBC 2018.
A new subsection appears in Section 1504.3—Wind Resistance of Nonballasted Roofs: 1504.3.3—Metal Roof Shingles. Listed are test standard options, including ASTM D3161, "Standard Test Method for Wind-Resistance of Steep Slope Roofing Products (Fan-Induced Method)"; FM 4474, "American National Standard for Evaluating the Simulated Wind Uplift Resistance of Roof Assemblies Using Static Positive and/or Negative Differential Pressures"; UL 580, "Standard for Tests for Uplift Resistance of Roof Assemblies"; and UL 1897, "Standard for Uplift Tests for Roof Covering Systems." Metal roof shingles tested in accordance with ASTM D3161 are required to meet the classification requirements of Table 1504.1.1—Classification of Steep Slope Roof Shingles Tested in Accordance with ASTM D3161 or D7158, "Standard Test Method for Wind Resistance of Asphalt Shingles (Uplift Force/Uplift Resistance Method)."
Section 1505.9 now is titled "Rooftop Mounted Photovoltaic Panel Systems" (formerly "Photovoltaic Panels and Modules"). The section requires photovoltaic (PV) panel systems installed on roofs be tested, listed and identified with a fire classification in accordance with two UL standards: UL 1703, "Standard for Flat-Plate Photovoltaic Modules and Panels," and UL 2703, "Standard for Mounting Systems, Mounting Devices, Clamping/Retention Devices, and Ground Lugs for Use with Flat-Plate Photovoltaic Modules and Panels." UL 1703 was referenced in the previous edition, but UL 2703 is a new reference. The section requires the fire classification comply with Table 1505.1—Minimum Roof Covering Classification for Types of Construction.
In Section 1505.10—Roof Gardens and Landscaped Roofs, a reference to Section 1505.1—General has been added to clarify the codes' intent that vegetative roof systems shall meet the requirements in Section 1505—Fire Classification.
Section 1507—Requirements for Roof Coverings contains a section-wide change where underlayment and ice barrier requirements formerly included (and repeated) in subsections addressing each roof covering type have been moved to single locations: Section 1507.1.1—Underlayment and Section 1507.1.2—Ice Barriers. Each subsection includes a reference to these new sections when appropriate. Material standards for underlayment are listed in Table 1507.1.1(1)—Underlayment Types, and application information is provided in Table 1507.1.1(2)—Underlayment Application.
In Section 1507.8—Wood Shingles, a new subsection has been added: Section 1507.8.9—Label Required indicating shingles bundles be identified by a label of an approved grading or inspection bureau or agency.
In Section 1507.9—Wood Shakes, a new subsection has been added: Section 1507.9.10—Label Required indicating shakes bundles be identified by a label of an approved grading or inspection bureau or agency. Also, in Table 1507.9.6—Wood Shake Material Requirements, a note related to American Wood Protection Association Standard U1 (AWPA U1), "Use Category System: User Specification for Treated Wood Except Commodity Specification H," Commodity Specification H has been updated to reference "Special Requirement 4.6" (formerly the reference was "Use Category 3B and Section 5.6"). AWPA U1 is associated with Southern Pine preservative-treated taper sawn shakes.
Subsection 1507.11.2.1—Base Sheet has been added and identifies three options: a sheet that complies with Section 1507.11.2—Material Standards; a sheet that complies with ASTM D1970, "Standard Specification for Self-Adhering Polymer Modified Bituminous Sheet Materials Used as Steep Roofing Underlayment for Ice Dam Protection"; or ASTM D4601, "Standard Specification for Asphalt-Coated Glass Fiber Base Sheet Used in Roofing."
In Section 1507.12—Sprayed Polyurethane Foam Roofing, an additional standard is referenced in Subsection 1507.14.2—Material Standards: ASTM D7425, "Standard Specification for Spray Polyurethane Foam Used for Roofing Applications."
In Section 1507.17—Photovoltaic Shingles, there is a change in Subsection 1507.17.2—Deck Slope. The minimum permissible deck slope has been changed to not less than 2 units vertical in 12 units horizontal (2:12). Formerly, the minimum permissible deck slope was not less than 3 units vertical in 12 units horizontal (3:12).
Section 1507.18—Building-integrated Photovoltaic Roof Panels is new and includes requirements for deck, deck slope, underlayment, ice barrier, material standards, attachment and wind resistance. Unlike other subsections in Section 1507, underlayment and ice barrier requirements are included within Section 1507.18 and do not reference Sections 1507.1.1—Underlayments and 1507.1.2—Ice Barriers.
In Table 1508.2—Material Standards for Roof Insulation, the standard listed for composite boards is ASTM C1289, "Standard Specification for Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board." The following insulation board types (per ASTM C1289) are indicated in Section 1508.2:
Type VIII is new for IBC 2018, and Type VI (faced with perlite insulation board on both major surfaces of the core foam) has been removed from the reference to reflect the most recent version of ASTM C1289.
Also, in Table 1508.2 the listed standard for wood fiberboard was updated. "Type II" was added to the reference for ASTM C208, "Standard Specification for Cellulosic Fiber Insulating Board," (previously, no type designation was indicated). Of the six types of wood fiberboard addressed in ASTM C208, only Type II is used for roof insulation.
Additionally, a listing for high-density polyisocyanurate board was added to the table, and ASTM C1289, Type II, Class 4 is indicated as a material standard. As part of the 13E1 edition of ASTM C1289, Type II, Class 4 was added to the standard to address high-density polyisocyanurate board.
Section 1510.7—Photovoltaic Panels and Modules has been simplified. A subsection related to wind resistance was removed because such requirements already exist elsewhere in the code. Also, wording requiring installation in accordance with the manufacturer's instructions was added to Subsection 1510.7.2—Photovoltaic Panels and Modules (the subsection has the same title as its parent section).
Section 1511.3.1—Roof Recover, Subsection (4) has been expanded to indicate roof coatings shall be permitted without tear-off of existing roof coverings. Identified substrates where such roof coatings may be installed as a re-cover include an existing roof coating; metal roof panel; metal roof shingle; mineral-surfaced roll roofing; built-up roofing; polymer-modified bitumen roofing; thermoset and thermoplastic single-ply roofing; and spray polyurethane foam (SPF) roofing. Previously, only SPF roofing was identified.
Roofing-related requirements also have been revised in Chapter 12—Interior Environment. Roof ventilation now is addressed in Section 1202—Ventilation (Ventilation was formerly Section 1203). A short introductory section has been added, Section 1202.2—Roof Ventilation, that indicates roof assemblies shall be ventilated in accordance with this section or shall comply with Section 1202.3—Unvented Attic and Unvented Enclosed Rafter Assemblies. Technical requirements for vented and unvented attics remain unchanged.
The International Energy Conservation Code,® 2018 Edition (IECC 2018) applies to all buildings with separate sections dedicated to address commercial and residential construction.
Several terms and definitions relevant to roof assemblies have been added or revised in Chapter 2—Definitions in the commercial and residential portions, including the terms air barrier, building thermal envelope, roof assembly and skylights (as part of the definition of "fenestration"). The definitions for these terms generally are consistent with those understood in the roofing industry.
Most noteworthy is the requirement for thermal resistance for roof systems has not changed. Specifically, the minimum required R-values listed in Table C402.1.3—Opaque Thermal Envelope Insulation Component Minimum Requirements, R-value Method and in Table C402.1.4—Opaque Thermal Envelope Insulation Component Minimum Requirements, U-factor Method have remained unchanged for roof systems.
A majority of IECC 2018's roofing-related requirements appear in Chapter 4[CE]—Commercial Energy Efficiency, Section C402—Building Envelope Requirements. Section C402.2—Specific Building Thermal Envelope Insulation Requirements (Prescriptive) contains two roofing-related subsections: C402.2.1—Roof Assembly and C402.2.1.1—Skylight Curbs. These subsections have been reorganized, but the technical provisions remain consistent with the previous version. New clarification text has been added to note two layers of insulation are not required where insulation tapers to the roof deck, such as at roof drains (generally two layers of insulation are required when continuous above-deck insulation systems are used per Section C402.2.1).
In Section C402.5.1.1—Air Barrier Construction, text has been added in subsection three addressing the sealing of penetrations through air barriers. The new text requires such sealing shall allow for expansion, contraction and mechanical vibration.
The International Fire Code,® 2018 Edition (IFC 2018) applies to all buildings though jurisdictions make the final determination as part of the adoption process. IFC 2018 contains several provisions applicable to roof systems.
Section 1204—Solar Photovoltaic Power Systems, Subsection 1204.1—General (formerly Section 605.11 in the previous edition) has new language indicating only the electrical portion of solar PV systems shall be installed in accordance with NFPA (National Fire Protection Association) Standard 70, "National Electrical Code.®"
Section 1204.2—Access and Pathways (formerly Section 605.11.1 in the previous edition) now requires pathways be over areas capable of supporting firefighters accessing the roof and located in areas with minimal obstructions such as vent pipes, conduit or mechanical equipment. Text has been eliminated noting roof access, pathways and spacing requirements need not be provided where the fire chief has determined rooftop operations will not be employed.
Section 1204.2.1—Solar Photovoltaic Systems for Group R-3 Buildings (formerly Section 605.11.1.2) has extensively been revised and, as with previous editions, does not apply to structures designed and constructed in accordance with IRC (IRC has its own requirements for access and pathways where rooftop PV is installed). New for IFC 2018 is an exception in Section 1204.2.1 indicating section requirements do not apply for roofs with slopes of 2 units vertical in 12 units horizontal or less. Section 1204.2.1 includes provisions for pathways to roof ridges and for setbacks at roof ridges. There also is alternative setback at ridge requirements for some buildings where automatic sprinkler systems are installed. Code users should be aware IFC 2018's Chapter 2—Definitions includes a listing for "Residential Group R-3." This listing is helpful for determining when Section 1204.2.1 is applicable for particular projects.
Section 3304.5—Fire Watch has been expanded beyond the single section included in the previous edition. The section now requires, where required by the fire code official or the pre-fire plan per Section 3308.3—Prefire Plans, a fire watch be provided for building demolition and for building construction hazardous in nature, such as temporary heating or hot work. Subsections include additional requirements that apply during new construction, to fire watch personnel conduct and training, and to fire watch location and records.
In Section 3304.6—Cutting and Welding, "open torches and other hot work operations" has been added to "welding and cutting" for those activities that shall comply with the requirements of Chapter 35—Welding and Other Hot Work.
The International Plumbing Code,® 2018 Edition (IPC 2018) applies to all buildings except detached one- and two-family dwellings and multiple single-family dwellings not more than three stories above grade plane, though jurisdictions make the final determination as part of the adoption process.
IPC 2018 contains changes from the previous edition that indirectly apply to roof system design.
Section 1106.5—Parapet Wall Scuppers (formerly Parapet Wall Scupper Location) has been expanded and applies where scuppers are used for primary roof drainage or for secondary or emergency overflow roof drainage. The section requires sufficient placement, sizing and quantity of scuppers to prevent water depth that would result in exceeding the maximum water depth buildings were designed to accommodate per structural requirements (IBC 2018's Section 1611.1). Section requirements also note scupper openings shall be not less than 4 inches in height and have a width that is equal to or greater than the circumference of a roof drain sized for the same roof area. Also, the flow through the primary system shall not be considered when locating and sizing secondary scuppers.
ICC intends for the most recent I-Codes to be adopted by jurisdictions beginning in 2018. Typically, the I-Codes are adopted at the local, county or state levels. In some instances, a jurisdiction may adopt one or more of the I-Codes but not all of them. IECC is most commonly adopted at the state level; however, in some instances, individual local jurisdictions may adopt IECC 2018 before state adoptions or in states without a state-wide energy conservation code.
Next month, in part two of "Keeping an eye on I-Codes," I'll address some of the more significant roofing-related changes to the International Residential Code® and International Existing Building Code.®
Jason Wilen, AIA, CDT, RRO, is an NRCA director of technical services.
The New I-Codes
The 2018 editions of the I-Codes include the following:
The 2018 editions of the I-Codes are available from the International Code Council at (800) 786-4452 or www.iccsafe.org. All I-Codes now are available except the 2018 International Green Construction Code, which is scheduled to be released during the first quarter of 2018 and, for the first time, will feature technical content based on ASHRAE 189.1, "Standard for the Design of High-Performance Green Buildings."
Conflicting climate zones
The 2018 edition of the International Energy Conservation Code's (IECC's) Chapter 3—General Requirements in the commercial and residential sections include climate zone information unchanged from the previous edition. For commercial buildings, IECC 2018's Section C401.2 provides code users with an option of using the 2016 edition of ASHRAE 90.1, "Energy Standard for Buildings Except Low-rise Residential Buildings," (ASHRAE 90.1-2016) instead of IECC as a method to demonstrate compliance with energy code requirements. This option creates a potential conflict as ASHRAE 90.1-2016 references more recent weather data than IECC 2018, resulting in about 10 percent of U.S. counties being in two climate zones—one for users referencing IECC 2018 and another for users referencing the same county in ASHRAE 90.1-2016.
For more information regarding the roofing-related provisions of the 2016 edition of ASHRAE 90.1, see "Setting the standard," September 2017 issue.
The following sections have been removed from the International Building Code,® 2018 Edition because the standards have been withdrawn by the Canadian General Standards Board (CGSB).
Section 1504.7—Impact Resistance, a reference to CGSB 37-GP-52M, "Standard for Roofing and Waterproofing Membrane, Sheet Applied, Elastomeric," has been removed.
Section 1507.11—Modified Bitumen Roofing, CGSB 37-GP-56M, "Standard for Membrane, Modified, Bituminous, Prefabricated, and Reinforced for Roofing," has been removed from Subsection 1507.11.2—Material Standards.
Section 1507.12—Thermoset Single-ply Roofing, CGSB 37-GP-52M, "Standard for Roofing and Waterproofing Membrane, Sheet Applied, Elastomeric," has been removed from Subsection 1507.12.2—Material Standards.
Section 1507.13—Thermoplastic Single-ply Roofing, CGSB CAN/SGSB 37.54, "Standard for Polyvinyl Chloride Roofing and Waterproofing Membrane," has been removed from Subsection 1507.13.2—Material Standards.
NRCA guidelines for rooftop-mounted photovoltaic systems
NRCA will release an updated version of NRCA Guidelines for Rooftop-mounted Photovoltaic Systems, 2018 Edition, in early 2018. The document will include code compliance information applicable to rooftop-mounted and building-integrated photovoltaic systems based on NFPA 70: National Electrical Code,® 2017 Edition; International Building Code,® 2018 Edition; International Residential Code® for One- and Two-Family Dwellings, 2018 Edition; International Fire Code,® 2018 Edition; and NFPA 1: Fire Code, 2018 Edition.