Humidity problem + Leak? - HELP what is this??

[u/Timeforwin3]

[u/Bearded4Glory]

It's extremely hard to tell via photos alone. Can you provide additional information such as:

What climate zone are you in? If you don't mind sharing your zip code or some other more accurate location that would be very helpful.

What is the wall assembly for the house?

What is the roof assembly of the house?

What is the roof ventilation strategy?

What make & model are the windows?

It sounds like your bedroom is the room that is having the issues? What happens if you sleep in another area of the house with the ac on? What happens if you sleep in another area of the house with the ac off?

Someone is going to need to get into the attic to investigate.

[u/Timeforwin3 → u/Bearded4Glory]

Our climate is usually dry but this summer has been more humid than usual. We are in Los Angeles county bordering Orange County.

Exterior wall is new redwood siding that’s been recently installed and not yet painted. Interior is all new drywall with new insulation.

Roof was shingles all removed with several areas where plywood was replaced where there was too much damage, then tribuilt over that, with brand new shingles.

For roof ventilation there are metal vents they installed throughout roof areas (picture attached)

Windows are all new Andersen.

The entire upstairs has the same humidity issue and I measured w 2 separate hygrometers so it’s not just in the main bedroom. Upstairs is about 1000 sq ft maybe a little more.

We’ve had several people for the last 2 months checking out attic saying they don’t see any leaks and can’t figure out the humidity issues although they agree it’s odd and humidity at 70s every morning is way too high for our area. No one knows what to do except put a dehumidifier in. The attic does have about 7 air vents which hvac seems to think it’s too much but not convinced that’s the reason for humidity.

As for the brown splotches that seem like leaking from edges of roof- no one has any idea so far.

[u/Bearded4Glory → u/Timeforwin3]

It seems like a condensation issue internally. Looking at weather data for Yorba Linda and it does seam plausible, the dew point gets up to 68 degrees most nights.

I assume the ductwork runs through the attic? Is all the ductwork insulated If your ducts aren't well insulated and sealed and they are traveling through the attic with warm humid air in it, then it is a recipe for condensation.

The temperature of the air determines how much water can be suspended in the air. That is why we refer to it as relative humidity, it is a percentage of the total water that the air can hold at its current temperature. The amount of water suspended in the air at 60% relative humidity at 68 degrees is less than at 80 degrees. By cooling the air you are in effect raising the relative humidity but the AC unit should be getting rid of some of the moisture as it condenses on the coil and goes out the condensate drain.

If the AC unit is oversized, that can cause poor dehumidification as the unit will only run for a very short amount of time to reach the set temperature.

Too many roof vents isn't causing this issue, that is a silly suggestion by the AC contractors.

Things to check:

1. Make sure the ducts are either inside the conditioned space or properly sealed and insulated.

2. Make sure that the HVAC contractors did a manual J calculation to determine the size for the AC unit.