Philadelphia chimney rules: permits, construction next door & CO alarms

This is a plain-English summary of the City rules most likely to affect chimney work on a Philadelphia house. It is not legal or code advice; the linked documents control.

Mechanical permits

L&I says you need a Mechanical Permit “to install devices regulated by the Philadelphia Mechanical and Fuel Gas Codes,” and that “a licensed contractor must perform all work.” Some kinds of mechanical work are eligible for EZ permits, which don’t require plans. Whether your chimney job needs a permit depends on the work; your contractor should tell you and pull it.

Fees for one- and two-family homes

From the Get a Mechanical Permit page and L&I’s fee summary effective October 1, 2026.

When a new building next door goes higher than your chimney

This is a uniquely Philadelphia problem: a neighbor adds a floor or a roof deck structure and your chimney or vent suddenly sits too low to draft properly. Under L&I Regulation B-3307.1.1:

• If a new or modified building extends above your roofline and your chimney or vent is within 10 feet, the person causing construction must take reasonable steps to have it extended or offset to meet code.
• They must send you a Notice of Required Chimney / Vent Modification at least 60 days before work, describing the impact and offering to get permits and fund or perform the extension.
• If you don’t respond, they can send a final notice at least 10 days before work. If you reject or ignore the offer, the regulation says you become responsible for your equipment’s compliance.
• The extension on your house needs its own mechanical permit, authorized by you.
• Pre-existing defects in your chimney are your responsibility. If a PA-licensed engineer says the extension can’t be done safely until they’re fixed, you get at least 60 days from notice to correct them.
• The rules don’t apply if the chimney is no longer connected to anything, or if a PA architect or engineer certifies it already complies.

Read the step-by-step guide if you’ve received a notice.

Carbon monoxide alarms

L&I Code Interpretation 0801 says the Fire Code requires CO alarms “in any new or existing building with a Group R-3 or Group R-4 occupancy” where fuel-burning or wood-burning appliances are installed, or where a garage is attached. In existing R-3 and R-4 buildings (the code groups that cover most one- and two-family homes), the alarms don’t have to be hardwired or interconnected.

Historic properties

If your property is on the Philadelphia Register of Historic Places, the Historical Commission’s project review covers “roofing and flashing,” “mechanical equipment and associated vents, pipes,” and masonry “pointing, repair, replacement.” Review is free and happens as part of the building permit; the City says staff approve over 90% of applications without sending them to the full Commission. The Commission’s October 2024 permit log shows staff approvals for chimney brick repair and replacement.

Contractor licensing

Philadelphia requires a Contractor License for construction businesses, and the Mechanical Permit page says a licensed contractor must perform the work. Ask for the license number and proof of insurance before you sign.