Boston, MA Building Safety: Carbon Monoxide Detectors (2026)
Key Facts
- Required at
- delivery to new tenant
- Standard incorporated
- 527 CMR 31
- Enforced by
- Inspectional Services Department
- Tenant inspection request window
- 24 hours
- ISD response time
- 2 business days
- Fine for violation
- up to $300 per offense
Summary
Boston Code § 9-1.4(B)(4) requires every property owner to provide and maintain a functioning carbon monoxide detector, per 527 CMR 31, in a rental unit before delivering it to a new tenant: a delivery-standard duty enforced by Inspectional Services alongside the unit's other move-in safety requirements.
(4) Carbon monoxide detectors. Upon delivery of a rental unit to a new tenant, the property owner must provide and maintain functioning carbon monoxide detectors in accordance with the requirements of 527 CMR 31.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: 2026 S-2: Current through Ordinance 2025 C. 14, passed 11-5-2025).
Full Breakdown
" Subsection (B)(4) states plainly: "Upon delivery of a rental unit to a new tenant, the property owner must provide and maintain functioning carbon monoxide detectors in accordance with the requirements of 527 CMR 31", the state Board of Fire Prevention Regulations' carbon monoxide alarm standard, which the city has folded into its own local delivery-standard ordinance rather than leaving to state enforcement alone. The same subsection separately requires smoke detectors "in or adjacent to sleeping areas" per 527 CMR or the state Fire Marshal's regulations, and treats a Boston Fire Department finding that a dwelling is adequately equipped with smoke detectors as satisfying that requirement.
4(C); ISD must inspect within two business days, and a confirmed missing or nonfunctioning detector is cited and enforced the same way as any other delivery-standard violation. Housing units owned or operated by federal, state or city agencies are exempt from this Section's requirements. 4.
Violations & Fines
A rental unit delivered without a functioning carbon monoxide detector is a § 9-1.4 violation: the owner gets 24 hours to 14 days to install one once cited, and failing to do so is punishable by up to $300 for the first offense, with a second $300 fine if a five-day follow-up inspection still finds it missing and $300 for each additional day after that.
Frequently Asked Questions
Does a Boston landlord have to install a carbon monoxide detector before a new tenant moves in?
What if my Boston rental didn't have a CO detector at move-in?
Are any Boston rental units exempt from the CO detector rule?
Sources & Official References
Other rules in Boston
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