How Many Smoke Detectors Do I Need: A Simple Guide

According to the National Fire Protection Association, the two most common reasons for fires are heating and cooking equipment being set ablaze. A smoke alarm can help detect these fires before they start.

All states require one smoke detector in each bedroom, level, and corridor next to living spaces. The total number of smoke alarms you need depends on your building size and square footage, the number of floors in your building, and the number of bedrooms.

A small house with a detector in every small room and a couple of large ones may need seven smoke detectors, for example. It’s important to know that there are two types of high-risk areas: those with lots of people present, like homes, office buildings, hotels, and dormitories, and those with highly combustible contents, like libraries.

In both cases, smoke detectors are required by law. Here we will go into detail on everything you need to know.

smoke alarm

How Many Smoke Alarms Do I Need Exactly?

Though we covered a general guideline for how many you need, there are some slight nuances by State. Organizations provide guidelines on how many smoke alarms you should have for optimal safety, so it is best to refer to their suggestions before making any final decisions. Below we have provided a chart of some of the nuances between states and what you should know.

Smoke Detector Standards  – How Many Smoke Detectors Do I need By State

StateHow many detectors need per sq ftNotesLink
CaliforniaOne on each level, including the basement, 1 in each bedroom, and 1 in the hallway outside the bedroomsBattery-powered smoke alarms must have a ten-year sealed batteryClick Here
New YorkOne on each level, including the basement, 1 in each bedroom being slept in, 1 in the common outside areaMust be powered by a 10-year sealed battery or hardwiredClick Link 1

Click Link 2
FloridaOne on each level, including the basement, 1 in each bedroom, and one outside each sleeping areaIt must be a ten-year, non-removable battery smoke detectorClick Link 1

Click Link 2
OhioAt least 1 in each bedroom, floor, and corridorNew dwellings must hold smoke alarms using both photoelectric and ionization systems.Click Here
ArizonaAt least 1 in each bedroom, floor, and corridorTen-year sealed battery smoke alarms requiredClick Here
GeorgiaAt least 1 in each bedroom, floor, and corridorTen-year sealed battery smoke alarms requiredClick Here
IowaAt least 1 in each bedroom, floor, and corridorIt must be a Dual-sensor alarmClick Here
MaineAt least 1 in each bedroom, floor, and corridorTen-year sealed battery smoke alarms requiredClick Here
LouisianaAt least 1 in each bedroom, floor, and corridorAll one or two-family dwellings must include ten-year sealed battery smoke alarms.Click Here
MarylandAt least 1 in each bedroom, floor, and corridorTen-year sealed battery smoke alarms requiredClick Here
North CarolinaAt least 1 in each bedroom, floor, and corridorAll newly installed smoke detectors must be tamper-resistant, ten-year lithium battery-operated alarms unless the dwelling unit already has a hardwired alarm and a battery backup.Click Here

If your State isn’t on here, it has the customary laws that require one smoke detector in every bedroom and level of your home. Individual localities may have specific laws, so watch out for that.

Where Are Smoke Detectors Required in a Home?

There are a few places where you should install a smoke detector:

  • On each level of your home
  • In each bedroom, especially if it has a closed-door
  • In any room with an attached bathroom or without natural light
  • Near any gas appliances or water heaters (Considering installing a detector right above appliances such as a stove will trigger many false alarms, try to install them on the other side of the room)
  • In any room where you have a fireplace or woodstove (Like gas appliances, try not to place a detector right above an open fireplace or woodstove to avoid many false alarms)

Which Type of Smoke Detector to Install in Your Home

smoke detector

There are two types of smoke detectors, ionization and photoelectric.

Ionization smoke detectors need low alpha particles to trigger the alarm. If the air is clear, then they may not go off.

Photoelectric smoke detectors use beams of light to detect tiny particles of smoke that can be more sensitive to conditions like smog. Some smoke detectors utilize both approaches.

Combination alarms use the best ionization and photoelectric methods, which provide superior protection against smoke. These are the ideal type of smoke detectors to purchase, yet they can be more expensive.

Maintaining Your Smoke Detectors

Smoke detectors can save your life. Changing the batteries and cleaning them regularly is important to ensure they work properly.

When it comes to smoke detectors, you should keep two things in mind: the type of battery and unit.

Different types of smoke detectors use different batteries, so make sure you have a new one on hand before you change the old one.

And different units need to be cleaned differently, so don’t forget that!

Most batteries should be replaced twice yearly (or every six months).

Most people remember to change their smoke alarm batteries by changing them at the beginning and end of daylight savings time.

Along with batteries, don’t forget to replace the alarm every ten years when the sensors lose the sensitivity that makes them effective.

Some alarms come with a ten-year sealed battery eliminating the need to test and replace batteries for a decade.

With ten-year sealed battery alarms, you will only need to replace the alarm itself every decade!

Difference Between Smoke Detectors & Carbon Monoxide Alarms

carbon monoxide detector

Fires are the most common cause of home accidents in the US, and carbon monoxide poisoning is one of the leading causes of death in fires. It is important to have a smoke detector and an additional carbon monoxide alarm to prevent these kinds of accidents. (1)

Smoke detectors are designed to detect smoke from fires. They usually use an ionization or photoelectric sensor (or both), which detects particles of light emitted during smoke combustion. Carbon monoxide alarms use a highly sensitive gas sensor that can detect small, invisible amounts of carbon monoxide from fireplaces, space heaters, and other gas-powered appliances in your home that emit carbon monoxide (CO) and carbon dioxide (CO2) when they operate. (2)

Smoke detectors and carbon monoxide alarms are crucial for preventing fires and protecting you from harm.

Purchasing Smoke Detectors

Smoke detectors are cheap, usually $10-$20 each. They also come in packs of 4-6 detectors, making them a very convenient buy for the consumer.

10-year sealed battery smoke detectors are considerably more expensive than standard versions, costing upwards of $70.

Planning and Implementing a Successful Smoke Detector Installation 

The first step to installing a smoke detector is finding the perfect location.

You want to try and find a spot that will not be in the way of anything but is as high up as possible.

The second step to installing a smoke detector is figuring out what type you need. There are different kinds of detectors with different features, so ensure you get one that will work best for your home and needs.

After finding the perfect spot, it’s time to install the unit, which can be done by using mounting brackets or screws and nails. 

(1) carbon monoxide –
(2) carbon dioxide –

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