Safety Tools

How Many Smoke Detectors Do You Need?

Have you asked the question ‘how many smoke detectors do I need in my home?’ and got no reasonable answer? Well, today is your lucky day, as this guide is aimed at answering that question. Do make sure to read through this guide, and you’ll find out how many smoke detectors you need in your home.

What is a smoke detector?

A smoke detector is a device that combines smoke detection and a loud alarm together in one unit. The alarm sounds if it detects smoke in large amounts, like in a fire.

A smoke detector, when properly installed, tested, and maintained gives you an early warning of a fire, which increases your chances of getting out.

Which Type of Smoke Detector to Install in Your Home

Most homeowners don’t know that smoke detectors come in two types: ionization smoke detectors and photoelectric smoke detectors. At this point, you might wonder why anyone even bothers with knowing the difference.

While it may not be made for the most riveting article to read, knowing how ionization and photoelectric detectors work differently can potentially save your life one day.

The two most common are ionization and photoelectric smoke detectors, as was mentioned above. Understanding the difference between these two technologies will help you determine which type of smoke detector to install in your home.

  • Ionization-type alarms have a small quantity of radioactive material between two electrically charged plates, called electrodes. When this material ionizes the air, it causes a current to flow between the two electrodes. During a fire, smoke entering the chamber disrupts the flow of ions between the electrodes, setting off the alarm. Ionization smoke detectors are typically more responsive to flaming fires.
  • Photoelectric-type alarms use a beam of LED light to detect smoke during a fire. As smoke particles from a fire hit the LED beams, the sensor detects a break in the beam and is activated. Photoelectric alarms are typically better at detecting smoldering fires.

Because you won’t ever be able to predict whether a fire in your home will be a flaming fire or a smoldering fire, the NFPA recommends using both types of alarms for the best protection. Many manufacturers make alarms with dual sensors. The other option is to use a combination of ionization and photoelectric smoke alarms.

Should smoke detectors be on the wall or ceiling?

Since smoke rises, it’s best to install your smoke detector as high as possible – either on the ceiling or high on the wall. Just remember to leave at least three meters between the smoke alarm and any cooking appliances.


Smoke alarms actually don’t need a ton of maintenance. They can be checked once a month with batteries replaced at least once or even twice a year, according to the U.S. Fire Administration (USFA).

An easy way to remember to do this is to change your smoke detector’s batteries when you change your clocks for daylight savings time. However, be sure to review your smoke detector’s user manual, as you may need to check your devices more frequently.

You’ll also want to do a visual inspection to make sure your alarm indicator is on. This makes sure that both your hard-wired and battery-operated fire alarm is properly connected and the batteries are working.

You should also occasionally vacuum and dust around the alarm. This way your device is clear of insects and dirt which can tamper with the effectiveness of the alarm.

When you check your batteries, make sure there is no corrosion, if there is you need to change the batteries. You also want to calibrate and test your fire alarm sensors based on what the manufacturer suggests.

When you perform these regular checks on the alarm system and replace the batteries, then your smoke detector and fire alarm will be in the best condition possible.

Where should smoke alarms be located?

There are two important things to remember when deciding where to put smoke alarms:

  • Most fires start in the kitchen.
  • Smoke alarms are to warn people asleep in bedrooms.

Install at least one smoke alarm on every level of your home, including the basement (but not in unfinished attics).

  • Put smoke alarms in the hallways that lead to each bedroom.
  • On floors without bedrooms, install the smoke alarm in or near each living area such as dens, living, and family rooms.
  • Put a smoke alarm on the ceiling at the bottom of any staircase leading to the upper floors.
  • Mount the smoke alarm high on walls or ceilings (remember—smoke and hot gases rise). Wall-mounted alarms should be placed at least 10 to 30 cm down from the ceiling. The ceiling-mounted alarm should be placed at least 10 cm away from the nearest wall. If ceilings are pitched, install the alarm near the ceiling’s highest point.

Where shouldn’t smoke alarms be located?

Smoke alarms shouldn’t be put in kitchens, garages, or bathrooms. This is because dust, steam, and exhaust can set off nuisance alarms (see “What are Nuisances Alarms” below). Nuisance alarms are often called “false” alarms. However, it isn’t a false alarm because the smoke alarm is doing what it is supposed to.

Don’t install a smoke alarm near a window or register, where drafts can affect alarm operation and sensitivity.

How Many Smoke Alarms Do I Need in My House?

Unfortunately, there’s no one-size-fits-all answer here. The number of smoke alarms your house needs will depend on your personal circumstances. At the very least, you should have a smoke detector on every floor of your house. Of course the more smoke alarms you fit, the more protection you and your home will have.

However, When it comes to protecting your family, the first step is to be prepared. Smoke alarms are your first line of defense against a house fire by providing your family with an early alert, giving them time to safely escape.

At First Alert, we provide reliable protection you can trust to help protect what matters most. Do you know how many smoke alarms does your home need to be fully protected and what type is best for your needs? Here’s what you should know:

According to the National Fire Protection Association (NFPA), smoke alarms should be installed on every level of your home, including the basement. Fire detectors should also be installed inside every bedroom and outside of each sleeping area.

For example, two-story home with three bedrooms should have at least seven smoke alarms. Homes that have a set number of hardwired alarms can still place additional battery-operated smoke alarms throughout the house.

There is no such thing as having too many smoke alarms in your home! Just make sure fire detectors are properly placed in each area.


Check out these tips for installing your smoke detectors correctly below:

  • Install smoke detectors listed by a qualified testing laboratory on every level of your home, including the basement. Make sure there is a detector in or near every sleeping area.
  • Mount smoke detectors high on ceilings or walls. Remember that smoke rises therefore ceiling-mounted detectors should be installed at least four inches away from the nearest wall; wall-mounted detectors should be installed four to 12 inches away from the ceiling. If you have questions, contact your local fire department.
  • Don’t install smoke detectors near windows, outside doors, or ducts where drafts might interfere wither their operation.
  • Don’t paint your smoke detectors; paint or other decorations could affect their operation.

Don’t install the smoke detector

  • On windows or sliding doors as the winds and air may not pick up the heat of smoke or fire
  • In humid or moist areas including the bathroom
  • In areas that easily collect dust and dirt including unfinished attics
  • In cooler rooms such as sunrooms or porches
  • Near ceiling fans or air vents
  • In garages, as they are often not temperature-regulated and the cooler temperatures may not detect smoke or fire

Smoke Detector Safety Reminders

  • Test the smoke detector monthly. According to the National Fire Prevention Association, test your smoke detector monthly to make sure it’s working properly. Most smoke detectors have a one-press test button that shines a light or sounds a test alarm to let you know the detector is working properly.
  • Replace smoke detectors every 10 years. Most detectors only last up to 10 years before needing to be replaced. As a best practice, write down the installation date for each smoke detector so you’ll always know when to replace it.
  • Replace batteries annually. To make sure your smoke detector is working properly, change the batteries at least twice a year. As a best practice, change your smoke detectors when you change your clocks for Daylight Savings Time.
  • Keep the smoke detector clean. Make sure your detector is free of dust, dirt, paint and other particles that may prevent the detector from spotting and alerting you of smoke. Vacuum it at least once a year or more as needed.


After going through the above guide, we believe you have gotten clarity on the number of smoke detectors you need. Hence, when buying smoke detectors, you know how many you need, and the areas you need to place them.