Pole Barn Condensation

[rk396]

I know this topic has been discussed, and i've read through what i could. However my situation seems to be a bit different then what others are experiencing.

I recently put up a pole barn, wood sides, trusses with a traditional roof (shingles). I have a ridge vent along the entire length (30' x 40' x 12'). It has a poured concrete floor. I have insulated the walls, and put up a vapor barrier, and i've insulated the ceiling with faced 6" insulation. So basically i have an attic. When the humidity increases i get a large amount of condensation on everything. So my question is do need to add a few vents along the walls (below the ceiling) to help sweep air through the barn? I'm thinking i've effectively sealed off the barn from the portion that vents.

Has anyone else experienced something similar, or any thoughts as how to help this situation.

thanks

 

[911mike]

I run ceiling fans 24/7 and have reduced the problem by 90%. I run them on low most of the time but sometimes conditions require high. Works great in the winter too.

 

[Kevin54]

RK....first off....Welcome to Garage Journal. Secondly, if you don't mind, could you put the State that you live in, into your profile? It makes it so much easier to answer a lot of questions that may arise. Everyone's location is different, with different climate zones.

I have to agree with 911Mike....ceiling fans and high humidity really helps out. As far as what causes the humidity, you can get very many answers, but no solution. My garage, and my son's garage is both built the same. Neither one of us has a vapor barrier under the concrete floor. In the summer, when the heat and humidity is really high, my floor is dry as a bone. My son's garage....he has to take a squeegee to get the moisture off of the floor. That is not exaggerating, and I have no idea as to why it does it. We live 20 miles apart.

Seeing that the garage of yours is done, the only thing you can do is to try and remedy the situation. You can't add vapor barriers under the floor now, you have a vapor barrier in the walls, and you have it in the ceiling. The best thing to do is add air movement, and that will be by ceiling fans. You don't need a lot, but you need some.

Hopefully you can add a couple in and remedy the situation.

 

[rk396]

Thank you both for the replies, I live in NY (Buffalo area), so the climate see's extremes. I did forget to mention that I have a vapor barrier in the concrete as well, so even with all the moisture i'm getting on the metal surfaces (cars, and equipment). The floor is quite dry.

I think the ceiling fans is a good idea, and i certainly have the extra outlets to accommodate that. Would just air movement be enough? or should there be some air exchange as well?

Thanks Again.

 

[sands35]

Basically condensation happens when you have the right combination of humidity and temperature.

Is this happening in the morning, evening or any time?

I'll bet the humidity is high because you have a tight envelope, but the night drops temperatures enough to force condensation. Yes, fans will help, but something to control the humidity level in the garage would be best. You can also warm it up somehow to keep surfaces over dew point.

 

[Ruthless53]

We have two large airplane hangars in Southeast Texas that are both metal. One 20,000 interior space and one about 8,000. About 3-4 times at the start of the spring we get bad bad condensation all over the airplanes and floor. You can't even walk on the epoxy floors without busting your tail unless you shuffle. It usually only happens 3-4 times and then for some reason doesn't happen again the rest of the year. Not sure why....

 

[600SL]

I'm running into the same problem this time of year in NC. Condensation happens when the temperature and dew point spread are close and there is a high relative humidity.

Fans will assist with convective evaporation of the condensate.

Maintaining the heat up about 5 to 10 degrees above the dew point is probably the most efficient solution since this usually occurs in the AM and not much heat is required especially if the garage is insulated and doors are not being opened or closed. Right now my temperature is 66° out and the dew point is 63. I walked in this morning there was no visible condensation but I could not light a match that was left out in the garage over night. I probably would have seen visible condensation if I was in there 2 hours ago. I haven't seen them But I will be looking into a thermostat that turns on heat with low temperature dew point spreads whenever the temperature is below 70° F.

Then of course there are dehumidifiers and AC which lower RH.

 

[MoparTrucks]

My pole barn is minimally insulated with double bubble and I have a ridge vent and air can circulate at the top of where the walls meet the roof because I never sealed that and I never have had a condensation problem while a buddy has a pole barn similar to mine and it literally rains in his shop.

I think part of it is where your shop is situated (mine is on a hill with good drainage and good wind flow) and I think making things too air tight contributes to the problem. I am curious to know others feelings about this theory.

 

[SALIV8]

Good info.

I have an exhaust fan I am prepared to hook up if this happens to me. Maybe I'll just short cycle the ducts so it's more of a fan..

I'd toss a couple floor fans in there for a few days to see if that helps before dropping money on ceiling fans.

 

[Daniel Dudley]

http://www.radonseal.com/radonseal-mitigation.htm

 

[smokem2020]

I live in Indiana. I think the problem is just like your iced tea in the summer. It's cold and the air is hot and humid. The concrete takes a few days to catch up with the weather. I try to keep my garage closed when it warms up quickly. Heating the space helps but cost money and looks stupid running the heat when it's nice out. I've dumped floor dry on the floor after removing the water. But that's messy too. It does dry and can still be used again. Moving your cars outside helps some as they warm up quicker. My dad bought a new car. Never drove it. Parked it in an unheated and Drafty garage. It rusted so bad it looked like it was drove only behind salt trucks. Good luck in dealing with this problem. I know it's irritating.

 

[sbarshie]

I had this issue with my old/current garage and the only thing that helped was to tear out the insulated ceiling and remove the kraft vapor barrier from the fiberglass insulation.
Then I put it all back up without the vapor barrier.
It was painful to say the least. My ceiling is OSB and having a breathable ceiling really changed things.

I left all the wall insulation with vapor barrier intact and reduced the trapped moisture to an acceptable level.

I say this helped, it didn't eliminate the problem entirely. Before removing the ceiling vapor barrier I was getting so much moisture coming throught the floor and trapped air that mold was a concern.

Running fans also helps when we have lots of rain and really moist ground, since I didn't but plastic under my floor.

I'm in PA where we get, snow, rain, heat and everything else you get.


BTW, my new place has the same pole barn construction you have and I'm real concerned about how insulate it because of my last exp.

 

[Novicaine]

I've don't this problem, but I put a vapor barrier down before pouring the concrete... did you or others with this problem?

In my old shop I did have this problem (75% sure I didn't put down vapor barrier), so in the summer I just ran a little window AC unit to keep moisture down and as a nice side effect it cooled it off. Since it was a little unit, it didn't cost much to run. One summer I didn't do this and a got a layer of green mold everwhere, ugh.

 

[Big Bad Dad]

You need vents in the soffits. Think of the ridge vent as an "exhaust" where the hottest air flows out. The soffit vents are the "intake" where the cooler outdoor air comes in and lets the moisture flow through the building instead of condensing on the cool surfaces.

 

[Jimmies63]

You need vents in the soffits. Think of the ridge vent as an "exhaust" where the hottest air flows out. The soffit vents are the "intake" where the cooler outdoor air comes in and lets the moisture flow through the building instead of condensing on the cool surfaces.

If you have a ridge vent, you need the right square footage of soffit vent to allow air in to **** the moisture out the ridge vent when the sun shines. Make sure you have soffit vents and they are not plugged.

Not sure you need or want a vapor barrier in the ceiling. That will only trap moisture. Let the attic heat up and draft the moisture out the ridge vent from air flow through the soffit vents.

Someone mentioned they didn't have a problem with OSB. That would absorb moisture and release it later. Same principal. Like a holding pattern for moisture between cool/evap cycles