Roofing Guide to the International Residential Code (IRC)

By Jack Gray, Roof Online Editor • Last updated October 2, 2022

Introduction
Note on Amendments to the International Residential Code
Chapter 1 Scope and Administration
Chapter 3 Building Planning
Chapter 4 Foundations
Chapter 6 Wall Construction
Chapter 7 Wall Covering
Chapter 8 Roof-Ceiling Construction
Chapter 9 Roof Assemblies
Chapter 10 Chimneys and Fireplaces
Chapter 11 [RE] Energy Efficiency
Chapter 18 Chimneys and Vents
Chapter 23 Solar Thermal Energy Systems
Chapter 24 Fuel Gas
Chapter 26 General Plumbing Requirements
Chapter 29 Water Supply and Distribution
Chapter 31 Vents
Chapter 44 Referenced Standards
Appendix H – Patio Covers

Introduction

This page references the 2018 International Residential Code. Although it’s not the latest version, the 2018 version of the code is currently the most commonly used.

Sections of the code which reference roofing or roof-adjacent aspects of construction are presented on this page. We also provide links to the building code for every chapter below so you can see the actual language of the sections you’re interested in.

You may be looking for the Roofing Guide to the International Building Code.

For a good guide to the entire IRC, consider getting DEWALT 2018 Residential Construction Codes: Complete Handbook. (Link goes to the book’s Amazon page.)

Search this page: This is a pretty long page. We recommend using CTRL+F to search for the exact words you’re looking for. Here’s how you do it on desktop and tablet. Here’s how you do it on mobile. If you don’t know this one simple trick, click that link, read the article, and learn how to do it. It will save you a lot of time in the future if you learn how. It’s easy.

Note on Amendments to the International Residential Code

Always check with your local building inspector’s office or website to be certain which version of the building code is in effect in your area.

New versions of the model International Residential Code are produced every 3 years, but they are not adopted or put into effect by local authorities every 3 years. In fact, they are not adopted with any consistency from country to country, state to state, or even city to city.

An important thing to be aware of is the fact that the majority of the governing authorities which adopt the codes do so with amendments.

The codes produced by the International Code Council are model codes, which means that they are simply standardized templates that the authorities in each actual jurisdiction can use as a foundation for their building codes. Some places will adopt the codes as they are, without amendments, but this is not very common.

Local authorities can (and they do!) add things, remove things, change the language, and make exceptions to the model code, so it’s not enough to simply know which version of the model code has been adopted.

Please see our page Building Codes & Roofing 101 • Important Facts & Guidelines for more information.

Chapter 1 Scope and Administration

See the full code for Chapter 1 on the ICC website.

See the full code for Chapter 1 on the UpCodes website.

Section R104 Duties and Powers of the Building Official

R104.10 Modifications (Roof Online Note: This section gives the building inspector leeway when it comes to enforcing the code. It allows you to present reasonable requests for code requirement modification if strictly following the code is impractical but the intent and purpose of the code will still be satisfied.)
R104.11 Alternative materials, design and methods of construction and equipment

Section R105 Permits

R105.2 Work exempt from permit
R105.2.2 Repairs

Section R106 Construction Documents

Chapter 3 Building Planning

See the full code for Chapter 3 on the ICC website.

See the full code for Chapter 3 on the UpCodes website.

Section R301 Design Criteria

(Roof Online Note: This section mentions roofs over 100 times.)

R301.2 Climatic and geographic design criteria
R301.2.1 Wind design criteria
R301.2.2.2 Weights of materials
R301.6 Roof load

Section R302 Fire-Resistant Construction

R302.2.4 Parapets for townhouses
R302.2.5 Parapet construction
R302.2.6 Structural independence

Section R308 Glazing

R308.6 Skylights and sloped glazing
R308.6.8 Curbs for skylights

Section R316 Foam Plastic

R316.5 Specific requirements
R316.5.2 Roofing
R316.5.3 Attics

Section R324 Solar Energy Systems

R324.4 Rooftop-mounted photovoltaic systems
R324.5 Building-integrated photovoltaic systems
R324.6 Roof access and pathways

Chapter 4 Foundations

See the full code for Chapter 4 on the ICC website.

See the full code for Chapter 4 on the UpCodes website.

Section R406 Foundation Waterproofing and Dampproofing

Chapter 6 Wall Construction

See the full code for Chapter 6 on the ICC website.

See the full code for Chapter 6 on the UpCodes website.

(Roof Online Note: This chapter mentions roofs over 200 times, mostly having to do with wall construction requirements which ensure that the walls can support the loads imposed on them.)

Chapter 7 Wall Covering

See the full code for Chapter 7 on the ICC website.

See the full code for Chapter 7 on the UpCodes website.

Section R703 Exterior Covering

R703.3 Wall covering nominal thickness and attachments
R703.3.1 Soffit installation
R703.3.3 Fasteners
R703.4 Flashing (Roof Online Note: Flashing requirements at wall and roof intersections, chimneys.)
R703.8 Anchored stone and masonry veneer, general
R703.8.2 Exterior veneer support
R703.8.2.2 Support by roof construction

Chapter 8 Roof-Ceiling Construction

See the full code for Chapter 8 on the ICC website.

See the full code for Chapter 8 on the UpCodes website.

(Roof Online Note: This chapter covers rafters, among other things. It mentions rafters over 200 times and includes rafter span tables. Also covers wood panel (plywood, OSB) roof sheathing requirements.)

Section R801 General

Section R802 Wood Roof Framing

Section R803 Roof Sheathing

R803.2 Wood Structural Panel Sheathing (Roof Online Note: This subsection covers plywood and OSB sheathing. See Table R503.2.1.1 for minimum allowable panel thickness by span and load.)

Section R804 Cold-Formed Steel Roof Framing

Section R806 Roof Ventilation

Section R807 Attic Access

Chapter 9 Roof Assemblies

See the full code for Chapter 9 on the ICC website.

See the full code for Chapter 9 on the UpCodes website.

(Roof Online Note: This is the main roofing chapter of the code. In particular, note that the Section R905 subsections for each different type of roofing material address deck requirements, slope, fasteners, underlayment, and flashing for that specific roof type.)

Section R902 Fire Classification

Section R903 Weather Protection

R903.2 FlashingR903.2.2 Crickets and Saddles
R903.3 Coping
R903.4 Roof drainage

Section R904 Materials

Section R905 Requirements for Roof Coverings

R905.1 Roof covering application
R905.1.1 Underlayment
R905.1.2 Ice barriers (Roof Online Note: “Ice Barriers” covers the installation requirements for ice and water shield.)
R905.2 Asphalt shingles (R905.2.8 Flashing, R905.2.8.2 Valleys, R905.2.8.5 Drip Edge)
R905.3 Clay and concrete tile
R905.4 Metal roof shingles
R905.5 Mineral-surfaced roll roofing
R905.6 Slate shingles
R905.7 Wood shingles
R905.8 Wood shakes
R905.9 Built-up roofs
R905.10 Metal roof panels
R905.11 Modified bitumen roofing
R905.12 Thermoset single-ply roofing (Roof Online Note: This section covers EPDM roofing.)
R905.13 Thermoplastic single-ply roofing (Roof Online Note: This section covers PVC and TPO roofing.)
R905.14 Sprayed polyurethane foam roofing
R905.15 Liquid-applied roofing
R905.16 Photovoltaic shingles
R905.17 Building-integrated Photovoltaic (BIPV) roof panels applied directly to the roof deck

Section R906 Roof Insulation

Section R907 Rooftop-Mounted Photovoltaic Panel Systems

Section R908 Reroofing

(Roof Online Note: This section covers the requirements for replacing an existing roof or installing a new roof over an old roof. It also tells you how many roofs (how many layers of roofing) you can put down on top of one another on a building and under what conditions.)

Chapter 10 Chimneys and Fireplaces

See the full code for Chapter 10 on the ICC website.

See the full code for Chapter 10 on the UpCodes website.

Section R1003 Masonry Chimneys

Section R1005 Factory-Built Chimneys

Chapter 11 [RE] Energy Efficiency

See the full code for Chapter 11 on the ICC website.

See the full code for Chapter 11 on the UpCodes website.

Section N1101 General

N1101.6 (R202) Defined terms (Roof Online Note: We recommend reading this subsection first.)
N1101.7 (R301.1) Climate zones
TABLE N1101.7 (R301.1)
CLIMATE ZONES, MOISTURE REGIMES, AND WARM-HUMID DESIGNATIONS BY STATE, COUNTY AND TERRITORY
N1101.10 (R303.1) Identification

Section N1102 (R402) Building Thermal Envelope