re: Brand new built home has high humidity. Normal?

Just in interest of easing the concerns of the OP, as a new build homeowner, obviously he needs verify the relative humidity (RH) in the house with other instruments - I’ve read too many articles stating RH on thermostats to be often highly inaccurate.

OP did ask in his initial post if it was normal to have high RH humidity in a newly built house and again everything I’ve read suggest it is common to have a high RH with all the water in lumber, concrete foundation, etc. which will eventually decrease as materials dry out. I moved into a new custom build but it was 30 years ago, I don’t recall excessively high humidity initially but that was a long time ago.

Been a lot discussion on an over sized HVAC being a/the cause. The OP never provided the square footage of the conditioned area of his house and the tonnage of his HVAC. If he told us he had 5-ton on a 2000 sq ft new construction, well-insulated home that would be a concern (over-sized). But if he has 3.5 or 4 ton unit on a 2500 sq ft conditioned area new build that’s likely properly sized and other issues are in play.

Anyway, don’t want the OP to freak out with some of the comments - just not enough info provided. But the thread has been a good discussion on possible causes of high RH in homes. The experts on a professional HVAC forum I follow, and this is USA wide, are fond of saying the most common issue they see with home comfort issues is over-sized HVAC systems (tonnage) with under-sized duct work.

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keep it between 70-72 during the day and 66 at night.

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I have a new theory for OP. Going from 66 to 72 in the morning is going to cause a very long period of the AC not running. Its cold AF in the house, hot and wet AF outside.

Sounds like a prime recipe for high humidity. Try leaving it on one setting for 36 hours and see what that does for you.

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Just in interest of easing the concerns of the OP, as a new build homeowner, obviously he needs verify the relative humidity (RH) in the house with other instruments - I’ve read too many articles stating RH on thermostats to be often highly inaccurate.

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^^^ this.

My Ecobee thermostats are off by about 10 % (shows higher) on relative humidity.

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Can someone tell me what’s a normal or good range for indoor humidity for a home in Baton Rouge area? Mine stays around 60% also.

I also have an Ecobee. I just purchased an indoor hygrometer to compare.

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60% is a bit high in my experience. In the summer when a/c is running regularly my house stays between 45-50%.

Winter time can vary bigly. A dry air cool front plus running the heater will put my house 35-40%. Cool wet weather will make the house 55-60% or higher, and that's when I pull out the standalone dehumidifier.

How does the house feel? My humidity says 70-80% on the thermostat but I’m sure it’s wrong and needs to be calibrated bc the house feels fine. We did have a refrigerant leak the first year we moved in and could definitely feel when the humidity went up.

I had a major renovation that included an entire roof lift. I added reflective insulation to the underside of the metal roof decking Thinking it was a good idea. Two units - 3 and 2 ton variable speed RUUD units. Interior humidity hovered above 60%. Two separate hvac contractors agreed the problem was over insulation in the attic. I thought they were crazy and told them so. Agreed to split cost of dehumidifiers if it fixed the problem. Humidity reduced to the target 50% within 2% and has remained in that zone for 9 months now.