Don't know where to post this... I own a first floor condo on a slab, built in the 80's. Ever since we have owned it the indoor humidity is very high, around 68%--even on dry summer days. You don't need a meter to know it is high because you can feel it, but I have used several different home thermometer devices and now my new Nest...they all agree.

There are no leaks under the sinks, toilet or bathtub. Windows were replace about 10 years ago.The bath fan works and the dryer vent is clear. There is carpet with stainmaster pad. I didn't notice any water stains on slab when the new carpet was laid. There is a downslope toward the building from the parking lot and it gets really wet there, the sprinkler system keeps it wet too. The humidity seems to get worse in sprinkler season. Found a crack in the foundation of the slab. It doesn't go all the way up to the siding. it is right behind the downspout which has an old old block under it. It goes down at least 4-5 inches based on a stick I stuck in it and is 6" deep into it (see photo). Could be deeper but didn't fit ruler...

What kind of professional can help me tell why it so humid all summer?? Even today with 29% humid outside it is 60%. It was 55% with the door open but went up when I shut the door and left. Also, the condo on each side of me does not have the high humidity, making me think it's the crack. I didn't ask the upstairs people. This is going to be a rental someday (year or so) but right now my son lives there, so I need to keep my expenses low and hopefully it is something the HOA should fix (foundation)