Akash Hirpara The International Residential Code (IRC) is the US model code for one- and two-family dwellings. Section M2302 and AM112/AM113 cover rooftop solar PV installations on residential properties.
Key Takeaways
- IRC governs one- and two-family residential construction in the US.
- References ASCE 7, NEC, and IBC structural provisions.
- Section AM112 covers PV installation requirements.
- State-by-state adoption with local amendments.
- Companion to IBC for commercial.
What IRC Actually Covers for Rooftop Solar
The IRC is a model code published by the International Code Council (ICC) and written specifically for detached one- and two-family dwellings and townhouses up to three stories — the housing stock that most residential rooftop solar gets installed on. States and counties adopt an IRC edition (2018, 2021, 2024, etc.) and then layer on their own amendments, so the exact section numbers and requirements an AHJ enforces can shift from one jurisdiction to the next even though the underlying code is the same.
Two parts of the code matter most for a solar plan set. Appendix RM (formerly the AM112/AM113 appendices in earlier editions) sets out photovoltaic system requirements — roof attachment, rapid shutdown coordination, and fire-service access — while Section M2302 addresses solar thermal and related mechanical provisions. Structural load path (rafter/truss capacity, attachment spacing, and wind/snow loading) is checked against ASCE 7 values referenced through the code, which is why a residential PV permit set typically needs a structural calculation package alongside the electrical drawings.
A Simple Way to Think About It
If IBC is the code a commercial rooftop array gets checked against, IRC is its counterpart for a single-family home. A plan reviewer looking at a residential system will confirm the array respects fire setback pathways, that the roof structure can carry the added dead load per the IRC’s structural references, and that the electrical work ties back to NEC requirements — all before the AHJ issues a permit.
Related Reading
Because IRC compliance sits at the center of every residential permit package, it’s worth pairing this definition with practical submission guidance: How to Submit a Solar Permit Package to an AHJ walks through the documentation a reviewer checks against IRC and NEC, and Commercial vs. Residential Solar Permit Design breaks down exactly where IRC and IBC diverge on structural, fire, and access requirements. Homeowners weighing a rooftop system in the first place may also find it useful to start with a primer on how rooftop solar works before getting into code specifics.
Frequently Asked Questions
3 commonly searched questions about IRC (International Residential Code).
What is IRC?
How is IRC different from IBC?
Solar in IRC?
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