A Philadelphia home should have a smoke alarm in every bedroom, outside each sleeping area and on every floor including the basement, plus a carbon monoxide (CO) alarm outside the sleeping areas and on every level if the house burns gas, oil or wood or has an attached garage. Landlords must provide smoke alarms on every level of a rented home. Owner-occupants of one- and two-family homes can ask the Philadelphia Fire Department to install smoke alarms for free through Philly311. And if you renovate under a City permit, L&I's standard calls for interconnected smoke and CO alarms in specific places, which usually means an electrician.
This is general information, not legal advice; rules differ for owner-occupied homes, rentals and permitted renovations.
Why this matters right now
October is when furnaces and boilers start running again in Philadelphia, along with gas water heaters, fireplaces and space heaters. Every fuel-burning appliance can produce carbon monoxide if its venting is blocked or it's badly tuned, and CO has no smell. The Consumer Product Safety Commission lists the symptoms of CO poisoning as headache, dizziness, weakness, nausea, vomiting, sleepiness and confusion, which are easy to mistake for the flu. An alarm is the only practical way to know.
In a rowhome or twin, bedrooms are often stacked above a single narrow staircase, so early warning matters.
Where smoke alarms go
The U.S. Fire Administration's smoke alarm guidance says to put smoke alarms inside and outside each bedroom and sleeping area, and on every floor, including the basement. It recommends interconnected alarms, so that when one sounds, they all sound. That matters in a three-story rowhome, where an alarm in the basement may not wake anyone on the third floor.
L&I's EZ permit standard for alterations (revised July 2026, based on the 2021 International Residential Code) spells out the same idea in more detail. For a one-family home being renovated under that permit, interconnected smoke alarms go:
- in each bedroom;
- outside each sleeping area, in the immediate vicinity of the bedrooms;
- on each additional story, including the basement;
- in the hallways;
- in a room open to the hallway serving the bedrooms if its ceiling is 24 inches or more higher than the hallway ceiling;
- at least 3 feet horizontally from the door of a bathroom (steam from a shower causes false alarms).
Kitchens and false alarms
If the alarm near the kitchen goes off every time you cook, don't pull the battery. USFA's advice is to move the whole alarm several feet farther from the kitchen or bathroom.
Ionization, photoelectric or both
Smoke alarms use two sensing technologies, ionization and photoelectric. USFA recommends having both types or dual-sensor alarms. The type is printed on the package and usually on the back of the alarm.
Where CO alarms go
The CPSC's carbon monoxide guidance is to install battery-operated CO alarms, or alarms with battery backup, on every level of the home and outside sleeping areas, and it says interconnected CO alarms are best. PGW's safety page recommends at least one smoke/CO detector on each floor and regular servicing of appliances, chimneys and flues by a qualified technician.
For permitted renovations, L&I's EZ standard requires interconnected CO alarms:
- outside each separate sleeping area, in the immediate vicinity of the bedrooms;
- inside a bedroom if a fuel-burning appliance is in that bedroom or its attached bathroom.
Combination smoke and CO alarms are permitted, which cuts the number of devices on the ceiling. Pennsylvania's law requires a combination unit to sound differently for CO and for smoke, so learn which sound means which.
Follow the manufacturer's instructions for how far to mount a CO alarm from fuel-burning appliances. The point is to wake people who are asleep.
What the law requires, by situation
You own and live in the house
Pennsylvania's Carbon Monoxide Alarm Standards Act of 2013 (copy posted by Middletown Township, Bucks County) doesn't order owner-occupants of single-family homes to install CO alarms. Its definition of "residential building" covers detached one- and two-family homes and attached single-family homes up to three stories with their own exit, a description that fits most single-family Philadelphia rowhomes. For those, the duty comes at sale: the seller must disclose information about carbon monoxide detectors on the property disclosure statement. If you're selling soon, installing alarms now gives you a simple answer for that form.
You rent the home out
The Philadelphia Fire Department's smoke alarm page says the landlord must provide smoke alarms on every level of a rented house or apartment, and tenants whose landlord hasn't done so can report it to Philly311.
For carbon monoxide, the state act applies to multifamily dwellings, meaning buildings with three or more households in separate apartments. If such a building has a fossil-fuel heater or appliance, a fireplace or an attached garage, each apartment needs an approved CO alarm near the bedrooms and the heater or fireplace. The owner must install it, replace missing or broken alarms between tenants, and make sure batteries work when a new tenant moves in. During the tenancy, the tenant keeps it in repair, tests it, replaces batteries and notifies the owner in writing of problems. Willful failure to install or maintain a required alarm is a summary offense with a fine of up to $50. The act also lets municipalities set stricter rules, so check with your township or borough in the suburbs.
Short-term rentals in Philadelphia have their own smoke and CO alarm requirements; see the City's short-term rental page.
You're renovating under a permit
When you renovate a one-family home under L&I's EZ alterations permit, the smoke and CO alarm locations above are part of the code requirements, and they must be interconnected. Expect the alarm work to be part of the job, and ask contractors to include it in their quotes. If the house is on the Philadelphia Register of Historic Places, L&I's standard says the EZ route needs prior approval from the Historical Commission.
Free smoke alarms from the Fire Department
If you live in Philadelphia in a one- or two-family home that you own and occupy, the Fire Department will install smoke alarms for free. Request it through Philly311, by phone or the app. The City's page notes it can take up to 90 days from request to installation, so don't wait until winter. Renters and apartment residents aren't eligible for this program; their landlord is responsible.
Battery, plug-in or hardwired
All three can be legal. Pennsylvania's act counts a CO alarm as installed if it is hardwired, plugged directly into an outlet without a switch, or battery-powered and attached to a wall or ceiling, in line with the NFPA 720 installation standard. An approved CO alarm must be listed to UL 2034 (or UL 2075 for detectors in a system); smoke alarms are listed to UL 217. Check the label.
- Battery-only alarms are the quickest fix for an existing house. USFA says to replace 9-volt batteries at least once a year; sealed long-life units are replaced as a whole.
- Hardwired alarms run on house power with a battery backup, which also needs replacing at least yearly per USFA. They are what a permitted renovation will usually get.
- Interconnection links the alarms so they all sound together. In a hardwired system that's an extra wire between alarms. Some battery models link wirelessly; check the manufacturer's compatibility list before mixing models.
Whatever you choose, USFA says to test alarms monthly and replace smoke alarms every 10 years. Check the manufacture date on the back; an alarm from before 2016 is due. For CO alarms, follow the replacement date or instructions from the manufacturer.
If the CO alarm sounds
CPSC's advice: if you suspect CO poisoning, get outside to fresh air immediately, then call 911. PGW gives the same instruction for suspected CO poisoning. Don't open windows and stay inside to "air it out," and don't go back in until responders say it's safe. If you smell gas, PGW says to leave and call 215-235-1212 from a safe place, without using light switches or anything that could spark.
CPSC also warns never to use a portable generator inside a home or garage, even with doors and windows open, and to keep it outside at least 20 feet from the house with the exhaust facing away.
Checklist for a Philadelphia home
- Count floors, including the basement, and bedrooms. You need a smoke alarm in each bedroom, outside each sleeping area and on every level.
- Add CO alarms outside sleeping areas and on every level if you have a gas or oil furnace or boiler, a gas water heater or stove, a fireplace or an attached garage.
- Check every alarm's manufacture date. Replace smoke alarms older than 10 years and CO alarms past the date on the label.
- Test every alarm. Replace batteries in older models once a year.
- Move any alarm that false-alarms from cooking or shower steam a few feet away rather than disabling it.
- Owner-occupant in Philadelphia? Request free smoke alarms through Philly311 now.
- Have the furnace or boiler, flue and chimney checked before heavy use. Our guides to the heating tune-up and the chimney inspection cover what that involves.
- Planning a renovation? Ask contractors to include interconnected smoke and CO alarms in the scope.
When to call a pro
Battery alarms are a DIY job: a drill, a ladder and the mounting plate. Call a licensed electrician for anything wired: replacing old hardwired alarms with a different brand (the connectors may not match), adding hardwired or interconnected alarms where there's no wiring, or alarm work that's part of a renovation. In Philadelphia, the City's electrical permit page says a licensed electrical contractor must perform all electrical work, and new wiring generally needs an electrical permit; repairs related to regular maintenance may not. In the suburbs, check with your township or borough. Old wiring in the walls you're opening up is worth a look at the same time; see our guide to knob-and-tube wiring.
If a CO alarm has gone off, the fix is on the fuel-burning side, not the wiring: once responders have cleared the house, have the furnace or boiler, water heater and venting checked by a qualified heating technician.
If you want quotes, you can post your electrical project on HomeKept. Say how many floors and bedrooms you have, what alarms are there now (battery or hardwired, and their age), whether you want them interconnected and whether it's part of a larger renovation. Photos of an existing alarm's back and of the ceiling where new ones would go help. It's free for homeowners, you can compare up to three estimates from local pros, and HomeKept covers Philadelphia, Bucks and Montgomery counties. A person reviews every pro profile, and license and insurance badges appear only after documents are checked. That isn't a background check, so use our guide to checking a contractor before you hire.
HomeKept is a brand of FalconAI LLC, 331 E Street Rd, Feasterville-Trevose, PA 19053.
HomeKept needs JavaScript. Please enable it and reload the page. ·
HomeKept necesita JavaScript. Actívalo y vuelve a cargar la página. ·
Для работы HomeKept нужен JavaScript. Включите его и обновите страницу.