Ionization smoke detectors / alarms were first invented in the early 1950’s and became commerically available for low-cost household use in the mid 1970’s. Since their widespread adoption into residential use, they have saved countless lives and provided an earlier warning to allow occupants the opportunity to escape housefires they otherwise would not have detected until too late. Carbon Monoxide (CO) detectors / alarms are a slightly more recent invention that also save lives from the silent killer that is carbon-monoxide asphyxiation.

Both of these alarms are readily available at hardware stores and even Walmart, although do note that you won’t likely find the word “detector” on any packaging. The manufacturers do this for legal reasons: if the device were to fail, they can state that they never claimed the device would “detect” smoke / carbon monixide! These low-cost devices are relatively easy to install but there are safety concerns if you are attempting to manually wire-them together. We always recommend you contact a qualified professional to install any smoke or carbon monoxide alarms in your home.


Where are Smoke Detectors / Alarms required to be installed?

Smoke detectors are required in every dwelling unit or home. Under current building standards, there should be a smoke alarm located in each sleeping room, outside each separate sleeping area in the immediate vicinity of the sleeping rooms, and on each additional story of the dwelling. What this translates into is: You need a smoke alarm in the room itself and outside of the room (i.e. the hallway) within 10-feet. If you have a multi-story home with all the bedrooms on one floor, you still need an alarm on the floor with no sleeping rooms. Sleeping room is a key-word here: technically, an office or a home theater room isn’t a sleeping room. We recommend you use common sense here: if the room is a place where people routinely sleep, you should have an alarm inside the room and within 10-feet of the doorway outside the room.


Quick Tips about Smoke Alarms:

  • Smoke alarms should be test at least every year. Devices that don’t respond properly or have a weak sound should be replaced. This is a great time to replace the 9-volt battery as well. Replace all the batteries at the same time unless you enjoy waking up in the middle of the night to sporadic chirping.
  • The manufacturers all state that these devices should be replaced after 10 years. We recommend you follow this advice.
  • When shopping for the alarms, we recommend you purchase the alarms that contain a 10-year lithium-ion battery so that you don’t have to change 9-volt batteries every year.
  • Smoke detectors are required to be inter-connected in modern homes. This means that they will all begin to sound if one of the alarms goes off. Older homes may not have this feature (or may not have smoke alarms at all!)
  • When shopping for the alarms, there are options to purchase units that inter-connect or purchase units that do not interconnect; make sure you know what you are purchasing. Most newer homes (built after 2000) have inter-connected alarms.
smoke alarm with batteries removed

Smoke alarms don’t work as well when you remove the batteries.

Where are Carbon Monoxide Detectors / Alarms required to be installed?

The placement of carbon monoxide detectors is a bit more forgiving: Under current building standards, there should be a carbon monoxide (CO) alarm located outside of each separate sleeping area installed within 10-feet of the sleeping rooms and on each story of the dwelling when a fuel-burning appliance is in place, a fireplace is in place, or the structure has an attached garage. Make sure you read that correctly: even if your home is all-electric, with no fuel-burning appliances and no fireplace, if you have an attached garage like 99.7% of all modern homes, you need carbon monoxide alarms in your home.

In practice, the most sensible way about installing carbon monoxide detectors is to install a smoke and carbon monoxide combination alarm outside of the sleeping room instead of a regular smoke alarm. This way, you minimize the number of batteries you need to replace each year and it looks better as well. The combination alarms are about the same price as a smoke alarm and a carbon monixde alarm combined, so it is just easier. Most all of the tips regarding smoke alarms applies to carbon monoxide alarms.


16400 Henderson Pass, STE 517
San Antonio, TX 78232

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Professional Home Inspector Kyle D. Scott

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Ensure Home Inspection San Antonio TX provides thorough inspections, detailed reports, and personalized consultations at affordable prices in San Antonio & surrounding areas. Home Inspector San Antonio providing WDI/Termite Inspections, Thermal Imaging, Pool / Spa Inspections, Foundation Elevation Survey and more!

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