Attic Humidity Control

[@asoulalignedhowgodhealshis6682]

Thank you so much for explaining things in a palatable way. I have really been struggling with the humidity level in my house. I have two units here on my property and both share an attic. Consistently, if I turn the AC on in either unit, the humidity goes up to 60 plus. I also have dehumidifiers in each unit and the lowest the humidity will go with the AC off is 48. The attic feel stifling and definitely not the same temp as outside. I live in so Cal, so it's not a particularly humid climate. I also have both AC furnace/air handlers as water heaters in my attic as well. Any help you can offer will be so appreciated. Thank you so much!

[@Neph1]

"it's the same as outside". I get it now. Thanks guys

[@sommasculpture]

You absolutely do not want the attic to be the same temperature and humidity as the outdoor air. That's a recipe for mold. You need to keep attic humidity below 50% year round

[@gypsyfrank4826]

Looks like the spray foamed ceiling in my attic blocked the ridge vent. So I should clear the foam back around the vent?

[@DBravo29er]

Yep. All those vents must be open.

[@BigPhi84]

The original video talks about traditional vented roofs, with soffit/gable vents and ridge vents. If your roof deck is sprayed with foam insulation, the roof has become the new thermal barrier (instead of the attic floor). In this case, the whole attic becomes “conditioned space” with the rest of the house, and the ridge vent and all other vents should remain sealed. (On a side note, with a spray-foamed houses with good sealing, a dehumidifier may have to be installed to remove excess moisture.)

[@waynepickard58]

I don't trust this guy--he doesn't make any sense. "The attic air is supposed to be like the outside air"??? Yes, except for 40 degrees hotter. When an attic is spray-foamed, you absolutely DO NOT want warm, moist outside air in the attic, or it will drop is humidity in the cooler environment and set up mold. Just like has been happening in crawl spaces for decades. They are mold as can be down there. Which is not good, but it is all much worse when the moldy space is overhead.

[@GregoryGuay]

Sounds like they avoided the topic of spray foamed attics.

[@bryantderuise728]

No, a foamed attic is sealed don’t open it! If there’s a humidity problem you don’t have enough foam or there’s outside air leakage. Add a dehumidifier until you figure out what’s going on.

[@WildBill1120]

My attic always feels much hotter than outside.

[@georgebennett785]

You full of it bud - an attic in the summer will ALWAYS be warmer that the outside. usually 10 to 20 deg higher

[@WildBill1120]

Right?! That comment made no sense.

[@davidhazen2394]

You are ignorant. He is saying that you need to fix your ventalztion so your tempreture are as close to the outside tempretuure as possible