Warm weather "condensation"

A couple of inspections this week. One has me baffled. It is a part time occupied guest house. 2 Levels. lower level a garage, upper level living quarters.

The owners say that almost every winter they suffer some condensation in three corners of the living area. I think that I can address that with more soffit venting.

However, now they have found staining on a ceiling joist, away from the others. and it is very slight.

No one is living there. House is closed up....windows closed. No smell of dampness, or moldiness.

It has been very humid the last month or so.

IDK. Any ideas, experiences like this?

twill59 Said: Theres widow lady with an ongoing issue. She has a beautiful room, Octagon, with a wood ceiling. No vents. Never had a problem until shingles, plywood insulation were replaced. She has no idea what was changed, but she did remember some rigid insulation.

Drips onto floor, pool table and ceiling fan. Some staining on beams and ceiling. This a year round problem.

For now I told her to reverse the ceiling fan and have it pull up air, instead of push down. Correct?

Udder n Dat, I told her wed have to remove 1 or 2 sections to get an idea of whats going on best fix/ add vents.

Maybe the plywood replaced 1x's instead of plywood. Most customers would not know the difference. Maybe they took out a moderate amount of insulation and packed it solid. Plus Egg's comments.

They used a non breathable underlayment. This would be my favorite.

I do not see what the fan direction would do? What are your thoughts that lead you to your conclusion. Would like to be able to use the deduction process.

Similar widow, similar octagon roof (actually hexagon in this case) similar drip (from the apex onto a table)

I have no firm grip on what has changed, but something has. For one thing, there is now a solarium in an adjoining room. But really, the dripping occurs in a living room, not a kitchen or a bathroom and not in the sunroom. Perhaps indoor plants getting watered when before there were none. Living habits changed...who knows...it can get a bit personal.

Similar comp shingles, similar apex cap. Old roof didn't condense, new one did. Not much, just enough to be annoying and without a towel to catch it, enough to potentially ruin the finish on a table.

I cut a small hole in the metal cap, added metal tabs to it wherewith to attach a low-profile fan vent hood and the dripping stopped.

This is what I do know...any air packet will contain water vapor until it reaches its saturation point. Immediately after it reaches saturation point it reaches dew point and water as gas condenses to water as liquid. If the temperature drops, moisture being held comfortably below saturation point may reach saturation point without any more moisture being added, simply because colder air packets can not hold as much water vapor as hotter air can.

Therefore the purpose of a fan is to stir the air packet and disperse the concentrated vapor being held within it thereby diluting it.

If you are dealing with a scissor truss, you will have a more complex network of air packets to deal with, any one of which, no matter how small, is theoretically capable of reaching saturation and then dew point.

Vapor wants to leave. Air wants to go from high pressure to low pressure. "All" we have to do is find where it's getting trapped and let it out.

Just my two cents. I imagine from the last update you're hot on its trail now anyway.

Pulled the ridge vent today...right after a downpour even. Dry. No signs of moisture.

Turns out that the "leaks" is on a false ceiling. The plot thickens

There's widow lady with an ongoing issue. She has a beautiful room, Octagon, with a wood ceiling. No vents. Never had a problem until shingles, plywood insulation were replaced. She has no idea what was changed, but she did remember some rigid insulation.

Drips onto floor, pool table and ceiling fan. Some staining on beams and ceiling. This a year round problem.

For now I told her to reverse the ceiling fan and have it pull up air, instead of push down. Correct?

Udder 'n Dat, I told her we'd have to remove 1 or 2 sections to get an idea of whats going on best fix/ add vents.

Thanks Natty, but if it was a roof leak, I'd a found it and been on my way.

But I am going to lift the ridge vent above this area. There is nothing else, just the field. And the stain on the joist is on both sides of ridge.

Another purpose is to inspect for airflow.

I have a client with some minor stains in a now enclosed front porch. Part of living room now. I did not put a vent on there. NO leaks during the 6" rain we got. I wonder if with the high humidity we had and the AC running if that'd be condensation. As I told them, when we cut the vent in, we'll check the insulation also

Unless they live in the attic, how would more soffit venting remove moisture in the living area? If this moisture appears in the winter, it is usually caused by a bare area of insulation over the ceiling. I have seen this happen at the ceiling near a wall where they did not insulate fully. It is particularly difficult to insulate the corners of a room after the sheetrock is installed with blown in insulation. When the temperature suddenly drops in a cold spell, the inside of the house will have a higher humidity and moisture will condense under those bare spots. Over time, mildew will stain those areas.

As for the staining on the ceiling joist, it probably is a roof leak.

Since seen-it-all has seen it all, what more can we add? I kind of agree with the both of you. I tend to think that if the building is breathing and air is moving all the time that the moisture will move out with the moving air. Problem solved. Boy, that was easy!

Just a random guess here. Would there be excessive heat trapped inside during a hot day and that would escape over night when the outside temperature is cooler thus creating a situation as normal heat loss during the winter? If the house is not being used then there is no chance of the hot air escaping via open windows, doors etc.