The Maryland smoke alarm law requires every smoke alarm to be replaced once it is 10 years old from its manufacture date before you sell. Battery-only alarms must be swapped for sealed 10-year units with a hush button, while hardwired alarms stay hardwired. For Bethesda and Montgomery County sellers, this is a settlement-day item — expired or missing alarms can trigger repair requests or closing delays, and replacement units run roughly $15–$60 each.
If you're getting ready to list your Bethesda home, smoke alarms probably aren't on your radar. They should be. Maryland has one of the stricter smoke alarm statutes in the country, and it's the kind of small, overlooked item that can turn into a repair request — or a closing-day headache — if you don't get ahead of it.
Here's the good news: coming into compliance is cheap and fast compared to almost anything else on a seller's to-do list. The trick is knowing exactly what's required before a buyer's inspector flags it for you.
Maryland tightened its rules after years of fire deaths in homes with dead or disconnected alarms, and the state now leans on the point of sale as a natural checkpoint. That's why this catches so many sellers off guard — you can live in a house for a decade without thinking about the alarms, then discover at listing time that every one of them is technically out of date.
What the Maryland smoke alarm law requires before you sell
The Maryland smoke alarm law says no smoke alarm in your home may be more than 10 years old, measured from the manufacture date printed on the back of the unit — not the date you installed it. Once an alarm hits that 10-year mark, it has to be replaced, whether it's hardwired or battery-powered.
The current standard took full effect on January 1, 2018, and it applies to essentially every single-family home in Maryland, including yours in Bethesda, Potomac, or Chevy Chase. Two rules do most of the work:
- Every alarm 10+ years old must be replaced. Flip your alarms over and check the manufacture date. If you can't find one, assume it's expired and replace it.
- New battery-only alarms must be sealed 10-year units. Any battery-operated alarm you buy to replace an old one has to be a sealed, tamper-resistant model with a non-removable long-life battery and a silence (hush) button.
That second rule is the one most sellers miss. You can't just pop a fresh 9-volt battery into a 12-year-old alarm and call it done. The whole unit has to go.
Battery-only vs. hardwired: what you actually have to replace
What you're required to install depends on what's already in the house — and this is where sellers get tripped up.
If your home has battery-only alarms (common in older Bethesda and Kensington homes built before hardwiring was standard), replace each expired one with a sealed 10-year alarm. These run roughly $15 to $40 per unit at any hardware store, and you can install them yourself in a few minutes.
If your home is hardwired (typical in newer construction and North Bethesda townhomes), you have to replace hardwired alarms with new hardwired alarms. You cannot legally downgrade a hardwired system to battery-only units to save money. Hardwired replacements are inexpensive on their own, but if the wiring is dated you may need an electrician, which pushes the cost up. Newer hardwired alarms also carry a 10-year battery backup, so plan to swap the whole interconnected set at once.
For most Bethesda-area sellers, full compliance lands somewhere between a $50 hardware run and a few hundred dollars if an electrician is involved. Here's how the numbers typically break down:
- Sealed 10-year battery alarms: $15 to $40 each, self-installed.
- Combination smoke/CO alarms: $40 to $60 each.
- Hardwired replacements: low unit cost, plus an electrician's visit ($150 to $400) only if the wiring or interconnection needs work.
A typical four-bedroom Bethesda colonial needs somewhere between five and eight devices once you count every level, every bedroom, and the hallways. Even at the high end, that's a couple hundred dollars — one of the lowest-cost items you'll handle before listing, and skipping it invites a far more expensive negotiation later.
Timing tip: do this before your listing photos and your first showing, not the week of closing. Fresh alarms photograph as a well-maintained home, and you never want a safety item outstanding while you're under contract with a firm settlement date.
Carbon monoxide alarms and where detectors need to go
Smoke alarms get the attention, but Maryland also requires carbon monoxide alarms in homes that burn fossil fuels — a gas furnace, gas water heater, fireplace, or gas range — or that have an attached garage. Given how many Bethesda and Potomac homes run on natural gas, that's most of them.
Placement matters as much as having the right units. As a practical baseline for a smooth inspection:
- Smoke alarms: on every level of the home, inside each bedroom, and in the hallway outside sleeping areas.
- Carbon monoxide alarms: outside each separate sleeping area and on levels with fuel-burning equipment. Combination smoke/CO units are allowed and simplify the layout.
Combination smoke-and-CO alarms cost a bit more — roughly $40 to $60 each — but they cut down on the number of devices on your ceilings and cover both requirements in one unit. If you're replacing everything anyway, combos are usually the cleaner choice.
One more detail worth checking: alarms should be the photoelectric or dual-sensor type that modern code favors, and the interconnected sets in newer homes should all sound together when one triggers. If yours don't, that's a sign the system predates current standards and is due for a full swap.
How this shows up at a Bethesda closing
Two moments in the transaction put smoke alarms front and center.
First is disclosure. The Maryland Residential Property Disclosure and Disclaimer Statement asks you to state whether the alarms are more than 10 years old and, for battery units, whether they're sealed tamper-resistant models with a hush feature. You're signing that document under penalty — so it pays to fix the alarms first and answer honestly. This is one of several line items sellers overlook on the form, and it's worth reviewing everything Maryland sellers are required to disclose before you fill it out.
Second is the home inspection. A buyer's inspector checks smoke and CO alarms as a matter of routine, and expired or missing units show up in the report almost every time. When they do, the buyer can ask you to bring them into compliance at your expense. That's a small fix, but it becomes leverage — inspection findings tend to get bundled together, and a stack of items reads worse than a clean report. If you want a sense of what else an inspector looks for, here's what Bethesda sellers should expect from the inspection.
Selling as-is doesn't get you off the hook, either. As-is refers to whether you'll make negotiated repairs — it doesn't waive a state safety statute. Your alarms still need to comply, and you still disclose their status under the Maryland smoke alarm law. This is exactly the kind of low-cost, high-friction detail I walk my clients through before we ever put a sign in the yard.
Handle it early and it's a $50 errand you forget about. Handle it at the settlement table and it's a delay. For a few dollars and twenty minutes with a screwdriver, there's no reason to let smoke alarms cost you momentum on a Bethesda sale.
If you're mapping out what to fix before you list, I'm happy to walk you through the punch list for your specific home and where it actually pays to spend. Reach out anytime.
About Pey Behin
Pey Behin is a residential real estate agent serving the Washington, DC metro area, with a focus on Bethesda, Montgomery County, and Northern Virginia. He works with buyers and sellers who want clear strategy, data-driven pricing, and direct guidance throughout the transaction process.