In June of 2013, ASHI (The American Society of Home Inspectors) went on record as recommending that all smoke detectors in homes be photoelectric type only. Since the Skip Walker treatise on the subject does such a better job of why this is so, I will not attempt to duplicate his content here.
Please see the ASHI Reporter article on the issue: Silent Alarms; Deadly Differences.
The article does a great job of explaining why stand-alone, hard-wired with battery backup photoelectric alarms are superior to ionization type alarms. It also discusses why combination alarms are not a solution. It also talks about why combining your smoke alarm with a CO detector is a bad idea.
Most smoke detectors have a 10 year life and should be replaced. As a home inspector all this information can make recommendations difficult, unless one is aware of the latest information on ionization type alarms versus photoelectric alarms.
Of course I have a blanket recommendation to upgrade the alarms in any home to photoelectric type alarms. Since it can be difficult to know just how old an alarm is, I often recommend upgrading at the time of moving into the home to establish a “history” for the alarms in the home. Another recommendation is to install “10 year” batteries in the units so that you don’t have to worry about changing batteries every year and that every ten years you simply replace the unit again. Most of the newer units are “dated” so that you can look at them and see how old they are.
The vast majority of homes in the US have ionization type alarms and more and more new homes are continuing to use them. Builders LOVE the combination Smoke alarm/CO detector units as an easy way to meet code requirements. It is frustrating, but I do not hesitate to recommend that the buyer to upgrade these brand new ionization alarms with technology that meets the latest and best information.
For the safety of my clients, it is not my fault that builders are not aware of the latest technology or do not care about the latest technology.
So for fire safety, in this heating season, please upgrade the smoke alarms in your home to the latest technology—go photoelectric.
The Holiday Season is house fire season; put a gift of photoelectric alarms under your tree this year.
Charles Buell, Real Estate Inspections in Seattle
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WA State, Home Inspector Advisory Licensing Board