Condensation question

[vrinner]

So I noticed this weekend when it was around 85-90 degrees out that I had a spot in the center of my floor that had a small puddles of water from what appears to be dripping from the center line of the ceiling. I'm assuming its from condensation and it's right under the connection that I've pointed out in the picture. I've heard that condensation is normal but I thought that insulation eliminates the problem. It's also weird that its at the high point of the ceiling.

Is there anything that can be done to eliminate this? I do not have any other venting in the building.

So my build is the following;
40X60X20 with a 1:12 roof steel building
R19 reinforced bat insulation in all walls
R30 reinforced bat insulation in the ceiling
2 each 12X14 insulated roll up doors

 

[Red 17]

IMO you still need some kind of ventilation and air circulation in a building like that.

You have an upside down petri dish there.

Just like I did....

 

[MFolks]

A great environment for mold to grow,expect mildew,and rusty tools,unless fans are installed and vents.

 

[vrinner]

That's what I was afraid of. Any recommendation on how to go about calculating what I need to do, like a vent on the side top and one on opposite side bottom...or a single roof vent be enough?

 

[Showkey]

Does the building have any climate control ?

Track the building temperature and humidity levels. If you don’t have control of the temperature and humidity there’s little chance to condensation.

Venting the building only helps if the outside air is better than the inside air as far as temperature and humidity.

If the indoor humidity is too high circulation in also not the answer.........dehumidifier might help, but circulation of wet air only spends money on electricity. Again measure and evaluate what the variables are.......then decide on the solution.

 

[coljar]

I have the same insulation you have on my ceiling. I heat and air condition my shop year around and run the ceiling fans 24/7. No problem for me, but I live in Ohio, not CA.

 

[Bretny]

Hold on a sec. Was the interior temp cold then you opened the doors to let the warm air in?

 

[vrinner]

Hold on a sec. Was the interior temp cold then you opened the doors to let the warm air in?

Yes...I went out around noon and it was still nice and cold inside the garage. I opened one of the roll up doors about 10' then noticed the dripping a couple of hours or so into working.

 

[HOTFR8]

IMO you still need some kind of ventilation and air circulation in a building like that.

I agree. Even a good fan would help in that situation.

 

[larry_g]

Yes...I went out around noon and it was still nice and cold inside the garage. I opened one of the roll up doors about 10' then noticed the dripping a couple of hours or so into working.

Warm humid air rushing into a cool metal area will cause condensation. Keep the big door closed is you can.

lg
no neat sig line

 

[Bretny]

Warm humid air rushing into a cool metal area will cause condensation. Keep the big door closed is you can.

lg
no neat sig line

Bingo!. Will happen every time its cold in the building, and warm humid air is let in. You dont really need more ventilation just keep the place closed when this twmp change is happening. Or allow for a small amount of air flow so things take longer to warm up.

 

[vrinner]

OK...that makes sense. I was thinking about putting some of those solar fans on the roof (from my neighbor) but I guess that may not be necessary.

I do notice that there is always a lot of condensation dripping off the outside of the roof but this is the first time noticing it on the inside and it's the first time I had the doors open when hot outside and cool inside.

I think for now I'll go with the advice of being more gradual if I'm opening the doors. I am planning on putting a large ceiling fan in (or maybe two). Cant afford those Big *** fans but looking for something big and less pricey.

Thanks for the advice!

 

[great white tj]

I am down here in Fl. and as others have said get some Fans and move the air..... I have a 24x24 shop and I have three fans going 24/7 ..... for this the fans are not High End Fans....just some cheep Wal-Mart fans.... your tools and other equp. will like you for moving the air...

 

[Red 17]

If you want to avoid roof penetrations, you can put an exhaust fan in the wall, with a duct up to the ridge. You would need the artistic touch when installing to have it look less odd, because it will look odd. But you will be pulling the hottest, wettest air out of the building.

Serving suggestion.

 

[vrinner]

So I pulled down some of the insulation where the drips were coming from and it is very wet inside. Pulled insulation from other areas where there were no drips and it was dry as a bone.

Called my builder and he is coming out tomorrow to check for any leaks in the roof. He is leaning towards a leak saying that once it gets inside there, it creates like a steam bath and you see the condensation like that. We will see what he finds tomorrow...hopefully it is just a leak.

FWIW...I have R30 in the ceiling (a layer of R11 and R19 with the white plastic on it).

 

[ard]

Moist air moving from inside to the cooler outside will condense during this 'trip'. SO an air leak that lets air move up into the insulation then eventually out of the building may show condensation when it gets 'behind' the insulation and onto cold portions of the roof deck, etc.


This is why it is critically important to have vapor barriers. In a home, it is the painted sheetrock that keeps the moist air IN the room, not getting into the wall/ceiling. But in garages and other buildings we see here, not so much.

GL

 

[vrinner]

So there was a screw hole that the missed. He dried it all off, put some sealer in the hole and put a new screw in it.

I have a large fan on some scaffolding blowing air into the opening to dry it out. I'll let it run for a couple of days till it's all dried out. Then I'll seal all the insulation back up.

Wondering...should I tape the insulation to the roof purlins and rafters to totally seal up any potential air leaks?

 

[Bretny]

Leave it open for a few weeks to check the repair and dry things out good.

 

[yeldogt]

I would make sure you fixed the problem .... check again

There can be situations where unconditioned metal buildings get cold -- all the structure is cold. When you open the doors and allow moisture laden air to enter from outside it can condense on the cold steel.

Plastic VB can be a problem .... often is.

A fan to expel the air .. just brings in more moisture. More of a problem. Moving air around with fans does nothing unless the building is large and the air in the building will counteract the air combing in from outside

The long term fix is some type of conditioning -- keep the air dry.

An unconditioned or under conditioned space is like being outside ... cold inside is no different than cold outside. If the surface is under the dew point ..moisture will condense.

 

[ard]

So, this was a leak? Only?

Not a 'condensation issue'?

(We should do a sticky on "Insulating my [garage/polebarn/whatever] that is sided with [stucco, wood, metal] and has an interior of [___]and will be [heated/AC/both/nothing] and i live in a [heating/cooling] environment A Compendium of wall designs". Or just link to green building designs I guess... )