Metal building condensation (help please)!

[Bama67]

Hello all,

A couple months ago I finally built (or had built) my dream shop, 40'x60' 16' eave steel building. My problem is, if is rains for a day or two, the condensation inside is TERRIBLE. Normal weather, it is fine. I have insulation, the thin-foil backed stuff R-10 value. So the metal is not exposed on the inside.

I am talking about bad, it looks like it is raining in there. Not just the water pouring off the purlins and beams. But anything that isn't cloth or wood is basically dripping with the stuff. Metal, plastic, etc.

My polaris ranger and fourwheelers are dripping so much water in the floor they look like I just washed them. My gun safe is pouring it off, my tools are rusted

This is an engineered steel building, and I think it is ridge vented.

I am thinking some serious ventilation would help this alot. But will it get rid of all of it? And I can't imagine how much a de-humidifier for this 2400 sq building would be.

I was think a pretty cupola would look nice, and I could put a big fan in there and I guess I would need some louvers on the wall? Or would I be better off with fans in the wall? How much air CFM/fan size do I need for this large building?

Thanks guys, I have been overseas basically since I built it, and will be home in a few days. My wife said it has been bad, and that alot of our clothes and stuff stored in there have mildewed while I was gone.

 

[Pete Judd]

In addition to adding vents, you need to warm the inside air to a temp just "at least" a little above the out side temp. The warmer the air, the more moisture it can hold. The science of it is that as the out side air as it enters the building warms, it's relative humidty will decrease and it's ability to more water will increase, then you move that wetter air outside.

On my sail boat, 46 ft. I just keep a 60 watt heater running all the time. 4 non powered vents, keep air moving through the boat and just the slight temp increase keeps everything dry and mold free. And this is in the wet PNW.

 

[Hollow]

Keeping it the same temp inside as it is outside is the key. A vent at each end should take care of it. Is the roof not insulated? Insulation will usually absorb light condensation and slowly evaporate it off.

 

[Bama67]

Thanks for the quick replies.

The entire building is insulated. It has that this stuff that has the radiant barrier on the outside, then like 1/2" fiberglass, then the white inside. R-10 value.

Sucks I have to keep it the same temp when it is cold outside. But I would rather work in the cold than all my stuff ruining.

 

[TonyF]

Hello all,

A couple months ago I finally built (or had built) my dream shop, 40'x60' 16' eave steel building. My problem is, if is rains for a day or two, the condensation inside is TERRIBLE. Normal weather, it is fine. I have insulation, the thin-foil backed stuff R-10 value. So the metal is not exposed on the inside.

I am talking about bad, it looks like it is raining in there. Not just the water pouring off the purlins and beams. But anything that isn't cloth or wood is basically dripping with the stuff. Metal, plastic, etc.

My polaris ranger and fourwheelers are dripping so much water in the floor they look like I just washed them. My gun safe is pouring it off, my tools are rusted....:

I occasionally have the same problem, but in a wood framed shop, tools, machines, cars all have moisture on them, I bought a free standing dehumidifier, ran a hose to a drain so it would not shut off when full, and let it run pretty much constantly, seems to keep most of the moisture at bay.
I also try to keep tools and machines coated with oil.

Tony

 

[slowzuki]

Dehumidify or heat the building during seasons with temp swings. After a cold snap, when a warm humid spell starts, it looks like someone turned on the hose inside. The areas where I insulated the slab aren't as bad but still get wet.

 

[Western]

I would say get the air moving, might test a couple of fans until you figure out what you need. You may end up with an intake fan or 2. I had a neighbor that had that problem and he put in 4 cheap ceiling fans (home type) and it made a huge difference only 20x20 shop). It is hard for moving air to condensate

Either way I think you need ventilation as the other guys have said, that is even a standard recommendation for house attics, they can have the same problem without air movement, but usually to a lessor extent since they get some temp abatement from the home structure.

 

[Hollow]

Thanks for the quick replies.

The entire building is insulated. It has that this stuff that has the radiant barrier on the outside, then like 1/2" fiberglass, then the white inside. R-10 value.

Sucks I have to keep it the same temp when it is cold outside. But I would rather work in the cold than all my stuff ruining.

Condensation should only happen when its colder inside than it is outside, right?

 

[slowzuki]

Yup, anytime its colder than the outside dew point you get condensation. Thats why just putting in ventilation isn't the solution. My shop is the worst when the big doors are open when its warm out and is still cold inside.

The fans don't stop condensation but they help stuff in the shop stay the same temp as the air so stuff doesn't condense on it.

 

[EddieWalker]

At any given temperature, the air can hold so much water. When the temperature drops to the point of 100% humdity, you get condensation. With a metal building, you get an inside temp and and outside temp that is seperated by a thin layer of metal. That metal transfers the lower temp to the higher temp and raises the humidity of the air to the point of creating moisture.

More air flow will help, but it takes quite a bit to accomplish anything. All you eves need to be open and a full ridge vent. Not just a cupola. You have to move a lot of air, and since air rises when it's warm, it will flow under your roof and out your ridge vent. This movement will minimize condensation.

Or you could increase your insulation. Right now, your insulation isn't doing the job. More insulation will seperate the two different temperatures from the outside and the inside enough to stop this from happening.

Last choice in my view would be to maintain the same temp or keep it warmer on the inside then the outside. I don't like this because it means using energy that will cost you money every month.

Do you have any pictures? I'm really curious about the insulation that you have in there now and why it's not stopping this.

Eddie

 

[radioman]

I think the OP is not getting full instructions or understand the concept how to resolve it. The problem can be resolved in one of either 2 ways. airflow or insulate correctly.

To have proper airflow, you need air inside the building to be nearly the same as outside. The proper way of doing it is to have outside air come in from bottom of building and flow out at top. This uses the sun convection air flow and pushes moisture upwards to either roof vent or gable. make sure its either roof vent or gable- not both or you will stop proper airflow.

The other way is to remove the foil insulation and have foam spray on the metal. Its the same concept as your foam coffee cup never condenses from hot or cold liquids. The problem with this is you need to have drywall or wall covering like plywood/osb to prevent fires from sparks.

If the OP is getting so much water dripping, I would verify the ridge vent is not blocked and leave the door open 24/7 until he can get 2-4 vents installed on both sides of bldg along the floor. problem is will the OP be needing to heat the bldg? then this will not work.


On a side note, if Op has water issues now with foil insulation, it may be no good now since its soaked and can mold.

 

[Gate Lavallee]

first of think you said new garage.....if it is a new slab on grade, well going to take a year to get humidity out of this slab, second me think you move air like other poster said from outside down to inside up or you heat the inside at resonable temp. and run de-humidefier for a good while. keep it hot or keep it cold with outside air going through it me think.

 

[mbohuntr]

Keep the air from touching the cold steel and condensating by spraying iso-foam on it.

 

[Bama67]

Thanks for all the replies.

I am still not sure what to do. I know I do not want to tear down $4,000 worth of two month old insulation and then spray several more thousands of spray foam if I can help it.

Understand it doesn't always seem to do this, only when it has been raining and the humidity is VERY high. Most days it is totally fine.

I guess I need to call the Steel building people that I bought it from. I mean, every building they sell like this pretty much will be built this way. See if they have any ideas. I don't think I have any pictures that would be of any help.

What I also don't get is that if I insulate the metal that is still exposed (purlins, beams) How is that going to keep all the stuff that is inside from condensating like it is now?

This building and all that has come with moving out here to our new place has tapped me out basically for now. This is so frustrating, I spent all this money for the building and my stuff might as well be sitting outside.

 

[AGGIE00]

We have corrected this issue by spraying one inch of closed cell polyurethane foam for insulation on quite a few metal buildings. The key is closed cell and not open for many reasons. The largest is the flame inhibitors in it. Closed cell requires an alternative fuel source to burn, and once the source is removed it extinguishes. Open cell is combustible and once ignited will feed on itself causing a rather severe fire hazard.

 

[Bama67]

We have corrected this issue by spraying one inch of closed cell polyurethane foam for insulation on quite a few metal buildings. The key is closed cell and not open for many reasons. The largest is the flame inhibitors in it. Closed cell requires an alternative fuel source to burn, and once the source is removed it extinguishes. Open cell is combustible and once ignited will feed on itself causing a rather severe fire hazard.

Okay, say I did tear down all the new insulation in my building. How much would it cost me to spray an entire 40x60 building with 16ft eaves, roughly?

 

[Bama67]

Alright, I got to thinking and looking back at my contract and supplies for my shop.

I don't think I have ANY sort of ventilation. This thing is sealed up tight, except a little gap above the roll up doors. Which I have 4 of.

So I am thinking I def need some type of ventilation. The large ridge vents, or a cupola or two? Wall mounted louvered fan, fan in a cupola? IDK.

I know I dont want to have to redo the insulation. I cant afford it if I wanted to.
This is depressing.

 

[EE_Bota]

Alright, I got to thinking and looking back at my contract and supplies for my shop.

I don't think I have ANY sort of ventilation. This thing is sealed up tight, except a little gap above the roll up doors. Which I have 4 of.

So I am thinking I def need some type of ventilation. The large ridge vents, or a cupola or two? Wall mounted louvered fan, fan in a cupola? IDK.

I know I dont want to have to redo the insulation. I cant afford it if I wanted to.
This is depressing.

I'd call the builder and tell them of the problems, and ask for a solution. If they request new money, cross that bridge when you come to it.

 

[lilranch2001]

I'd call the builder and tell them of the problems, and ask for a solution. If they request new money, cross that bridge when you come to it.

Get some sort of professional advice, even if it costs a few hundred to get a consultation.
Better to spend it wisely rather than foolishly

 

[moored4]

Condensation should only happen when its colder inside than it is outside, right?

Condensation happens when warmer wet air hits a colder surface. I still have snow on the top of my tin roof with 3 sides open it rained in side there all day :laughing: as it was 46 deg. and the sun shining today and was very humid with the snow we got last week melting. :thumbsup: