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Code Interpretation: Fire Separation
We received a question from our Facebook Group regarding fire separation at the garage.
Gary, I’ve never been able to get a definitive answer on this, so I’m going to ask it here. Should there be fire separation (a party wall type installation?) in an attic over a garage and the attic over a habitable space? I’m only asking about the attic space.
This is a fantastic question that highlights a common area of confusion, especially for inspectors navigating the intricacies of the IRC.
Let’s break this down. In most cases, a vertical fire separation wall within the attic itself is NOT required based on Table R302.6. Here’s the code citation:
“R302.6 – Dwelling-garage fire separation. The garage shall be separated as required by Table R302.6. Openings in garage walls shall comply with Section R302.5. Attachment of gypsum board shall comply with Table R702.3.5. The wall separation provisions of Table R302.6 shall not apply to garage walls that are perpendicular to the adjacent dwelling unit wall.”
Two Important References
Looking at table R302.6, notice the first row: ‘From the residence and attics.’ It states: ‘Not less than 1/2-inch gypsum board or equivalent applied to the garage side.’ There’s no mention of a vertical separation within the attic space.
| Separation | Material |
|---|---|
| From the residence and attics | Not less than 1/2-inch gypsum board or equivalent applied to the garage side |
| From habitable rooms above the garage | Not less than 5/8-inch Type X gypsum board or equivalent |
| Structure(s) supporting floor/ceiling assemblies used for separation required by this section | Not less than 1/2-inch gypsum board or equivalent |
| Garages located less than 3 feet from a dwelling unit on the same lot | Not less than 1/2-inch gypsum board or equivalent applied to the interior side of exterior walls that are within this area |
During a visual inspection, it’s equally important, and sometimes more challenging to determine, the specifics of the second row: ‘From habitable rooms above the garage.’ It indicates when a bonus room (or habitable space) is installed over the garage, install 5/8-inch bypsum board or equivalent.’
✅ Inspection Tip: When inspecting a garage with a bonus room overhead, if you can’t access the drywall from above to see the drywall fire rating stamps and other means of identification, remove the cover plate at a ceiling receptacle and confirm.
Report writing best practice: ‘Sometimes it’s more important to say what you can’t see than what you can.’ If you can’t confirm proper fire separation, say it in the report.
In this instance, installing a vertical separation wall in the attic, while perhaps not harmful, would exceed the code requirements outlined in Table R302.6. The term “minimum” in fire safety codes establishes a baseline; however, this doesn’t mean it’s a limit to creativity or a barrier to better design choices.
Conclusion
Far from being troubling or unnecessary, surpassing the code is a personal decision that can enhance safety, provide peace of mind, or accommodate unique building needs. Few of us want the bare minimum, but that is precisely the outcome when ‘building to code.’ The code, carefully crafted by experts, balances protection with practicality, but it’s not the maximum you must achieve—it’s the foundation you start from.
The key is recognizing that the minimum codes are designed to keep us safe, while anything more is up to you. I use CodeCheck. I have the digital version on my iPad, which has a fantastic illustrated guide to the current codes.
Always check for local code amendments. While the national code provides a baseline, many state and local jurisdictions often have specific modifications. It’s crucial to know local adoption interpretations.
Last Word
This discussion highlights the importance of the inspector’s continuing education and peer review reports. Misinterpreting code requirements can lead to unnecessary costs for homeowners and potential liability for consultants. Never hesitate to ask questions and seek clarification from experienced professionals or your local building department.