Indoor Humidity Changes

[kholmseth]

We have an indoor heated pool that stays between 80-85 degrees right now without turning on the heater, due to higher outdoor temps. It has a solar blanket cover on it, at all times. Lately, our humidity has been going up to 60% or a little higher on days that it's been raining. (the outdoor humidity is 87% or so). On these days, we are able to control the indoor humidity with both a ceiling dehumidifier fan system (honeywell), and a regular floor unit dehumidifier to about 53-58%. We cannot get it any lower than this on rainy days. When it's dry, it drops back down to 48-50% with no problem. We are concerned that if it continues to rain, this will be a mold-growth problem. Are these humidity ranges an area of concern? We are new owners to this home, and we were told to keep it between 40-50%, but it's been a challenge. Thanks for any advice!

[odbob]

I can see your concern, mainly due to advise of 40 to 50%, and with outside humidity in the order of 87%, . I am surprised that you were advised of 40 to 50% as this is a pretty low figure, my pool area is typically in the region of 60%, rising to 80% following a swimming activity and we suffer absolutely no mold growth. I should say at this point, that our pool cabin is extremely well insulated and so where mold growth would normally occur, around the perimeter walls, the internal wall temperature is virtually the same as the air temperature and so no condensate forms. To me circulating the internal air would be the way I would go, maybe even add fans in strategic places to assist the fans already incorporated within the dehumidifiers, but I also think that your experience of 60% plus is not something to unduly worry about, that said, every situation is different and so keep an eye on it, don't let mold growth occur.