@Stashing Away , your experience with smoke detectors may vary based on the climate where you live. If it's really humid, smoke detectors may be more problematic. Twenty years ago, we built a brand new house in a very humid part of the country. Codes required that we have half a dozen, or so, hardwired smoke detectors in various parts of the house. After many, many sleepless nights wandering around the house in pajamas, searching out randomly beeping smoke detectors, we finally disabled all of them. It was just too frustrating to deal with the continual, and seemingly random false alarms, which usually came in the middle of the night, almost always when it was raining hard and RH was at, or near, 100%. Talking with neighbors in our old neighborhood, pretty much everyone experienced the same frustrations with various brands of smoke alarms. We didn't know anyone whose smoke alarms actually functioned properly in that climate. It may be that modern smoke alarms have been designed to overcome the problems we experienced. We're living in a different, much older, house now.
Again (not to sound negative, but just from a building science perspective), this is a ventilation/ air quality issue. A 20 year old house should not be mismanaging humidity so much that it is setting off smoke alarms during a rainstorm. At least in principle- I don't doubt that you and your neighbors had this problem. If you have that much humidity constantly I can guarantee you are growing mold in many places that you don't want. Getting a dehumidifier solves many problems in a climate like this, many of which will improve your health. I don't speak from direct experience in the humid south, so grain of salt, but I do spend a lot of time on building science.
We were living in a part of Hawaii that gets an average of 150' of rain a year. About 3/4 of the precipitation comes between sunset and sunrise. Daytime was often beautiful, and then the rains would last all night. We designed our house with a full hip roof with 4'+ overhangs on all sides. Pretty much all of our wall space was taken up by windows. My wife used to complain that there was nowhere to put furniture, because we had "too many" windows. Tradewinds blew in off the ocean and pushed air in one window of the house, through the living space, and out the other side. Coldest it ever got on the rainiest, windiest night of the year, was ~50F. We never had a need for any type of HVAC system. A dehumidifier would've been useless, because the windows were open, pretty much, 365 days/year. Occasionally, during a big storm with horizontal rain, we'd close some windows to prevent water from coming inside, but we never needed to do that for more than a few hours, and we never closed all the windows, just the ones on the side of the house where the wind was blowing rain inside. On rainy nights, RH was always around 100% outside and, thus, inside as well. In the morning, sun would come back up, things would dry out. Never had any trouble, at all, with mold in the house. Based on advice from neighbors who had built their houses before us, I used the same exterior grade paint containing a mildewcide on all interior walls that we used to paint the outside of the house. All of our closets and the bathroom doors had louvers to allow for airflow, so there was always fresh air flowing through the house. It was a pretty extreme climate, so it's not that surprising that smoke detectors weren't designed to work well there. Planning on getting some, with CO included, for our place in PA soon.
