Honolulu County, HI Building Safety: Carbon Monoxide Detectors (2026)
Key Facts
- Applies to
- New buildings, qualifying renovations
- Renovation trigger
- Exceeds Chapter 18 valuation
- Battery-only allowed
- Limited exceptions only
- Citation
- Building Code § 915.1
Summary
New buildings on Oahu must have carbon monoxide detection, and existing dwellings trigger the same requirement once a permitted addition, alteration, or repair crosses the Chapter 18 valuation threshold.
915.1 General. Carbon monoxide detection shall be installed in new buildings in accordance with Sections 915.1.1 through 915.1.6. When the valuation of an addition, alteration or repair to an existing dwelling and sleeping units exceeds the valuation specified in ROH Chapter 18 and a permit is required, or when one or more sleeping units are added or created in existing dwelling units, carbon monoxide alarms shall be installed in the locations specified in Section 915.2 and the installation shall be in accordance with Section 915.4. Exceptions:
1. Repairs to the exterior surfaces of an existing Group R occupancy are exempt.
2. Carbon monoxide alarms are permitted to be solely battery operated where the code that was in effect at the time of construction did not require carbon monoxide detectors to be provided.
3. Carbon monoxide alarms are permitted to be solely battery operated in dwelling units that are not served from a commercial power source.
4. A carbon monoxide detection system in accordance with Section 915.5 shall be an acceptable alternative to carbon monoxide alarms.
(78) Amending Section 916.2. Section 916.2 is amended to read:
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-10: Supplement 10, 12-2025 Ordinance No. 25-40 through Ordinance No. 25-56).
Full Breakdown
Honolulu's Building Code requires carbon monoxide detection in all new buildings (Section 915.1). Existing dwellings and sleeping units must add CO alarms too once a permitted addition, alteration, or repair exceeds the valuation threshold set in ROH Chapter 18, or when a sleeping unit is added. Alarms may run on battery power alone only if the code in effect at construction didn't require detectors, or the unit lacks a commercial power source; exterior-only repairs are exempt.
Violations & Fines
Building officials can withhold final inspection approval on covered new-construction or renovation projects that lack the carbon monoxide alarms required under Section 915.1.
Frequently Asked Questions
Does Honolulu require carbon monoxide detectors?
Can I use a battery-only CO alarm?
Sources & Official References
Other rules in Honolulu County
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