Metal building condensation (help please)!

[jejeosborne]

I would not advise any type of venting unless you never plan on conditioning your barn. If you ever plan on heating this building, venting is not an option. Venting is for unconditioned spaces such as attics and crawlspaces. Venting prevents the differential temperature issue I previously mentioned. You could have just built a carport type structure if theft and conditioning wasn't an issue.

 

[clemsonfor]

I have an open carport with corrogated thick metal roofing. It is say 20x24 and open on 3 sides. Its attached to the house but to a florada style porch that is not heated or cooled and sometimes has at least one or two windows open on it so its not like its heated or anything.

Anyway my point it on rainy or damp cold mourings as it warms up or on a day after really cool ones and the concrete pad is holding the cold it will have a soaking wet floor, also as it warms up it condenses on the roof to the point that it "rains" under the carport.

 

[jejeosborne]

I have an open carport with corrogated thick metal roofing. It is say 20x24 and open on 3 sides. Its attached to the house but to a florada style porch that is not heated or cooled and sometimes has at least one or two windows open on it so its not like its heated or anything.

Anyway my point it on rainy or damp cold mourings as it warms up or on a day after really cool ones and the concrete pad is holding the cold it will have a soaking wet floor, also as it warms up it condenses on the roof to the point that it "rains" under the carport.

Your roof would have to be colder than the air for condensation to occur. I guess there may be short periods of time this happens but it doesn't take long for thin metal to achieve the same temp when exposed to the same air temps on both sides. Concrete can store a lot of cold energy so it is more a problem.

 

[Garybake]

What about hooking up a humidistat to an alarm that can be tweaked just before condensation point and will let him know to fire up a torpedo heater before condensation on equipment starts. As long as shop stays a little warmer than extreme stabalized cold to warm damp temp fluctuation should keep moisture from condensing. Just a quick fix thought for extreme seasonal fluctuation. If it has been cold for days and warm forcast is predicted quick heat would help. (A 35 degree drink brought to 48 on an 85 day will not condensate as much. I would prefer a foam wrapper around it but what are you going to do?)

My only sollution to maintaining a constant minimal heated area halfway between temp extremes.

 

[lilranch2001]

I still say let the slab cure out some and see if the condensation is minimized at that point.

 

[newbury]

Since soil does not contain air, there is no humidity in soil. Air contains massive amounts of air.
Eddie

Uncompacted "soil" contains air.
Air contains 100% air.

I have an open carport with corrogated thick metal roofing. It is say 20x24 and open on 3 sides. Its attached to the house but to a florada style porch that is not heated or cooled and sometimes has at least one or two windows open on it so its not like its heated or anything.

Anyway my point it on rainy or damp cold mourings as it warms up or on a day after really cool ones and the concrete pad is holding the cold it will have a soaking wet floor, also as it warms up it condenses on the roof to the point that it "rains" under the carport.

I've a similar situation in a shed I recently bought in NE Mississippi.
Building about 40x60, all metal, unheated (no need in Ms.) rains for a while on mornings when it was below freezing and whatever moisture which condensed on the roof comes down, as the sun warms the roof.

I've had recommendations of insulating the roof (coffee cup analogy).

My question is - what would be the best way? DIY kits run around $1/sq ft for an inch thick. Should I just cut up styrofoam cups from along the interstate and glue them to the ceiling? If professional install is $1/sq ft where should I go for bids?

Picture is prior to purchase, and yes the roof leaks slightly and I'm getting it fixed.

 

[EE_Bota]

I did a Google search (without quotes) of "condensation in metal buildings."

This site
Controlling condensation in metal buildings

and

This site

Design & Build With Metal: Understanding Condensation In Metal Buildings

were most interesting to me. Metal buildings represent a great deal of value for the cost. But much of what I am reading gives me pause. I don't own a metal building, but I know folks who do. I had never considered that in my conventional garage, that is it a blessing that my tools are not getting wet and rusty. I thought that was a given..but that shows what I knew, or thought I knew.

Of all the options I have seen or considered...I'd be tempted to add ventilation so air can free flow from low in the building directly out and through the roof ridge vents. Then I would consider fans...depending on the size of the building...perhaps several ceiling fans (like in a house) turned off and on based on a humidistat. This is to keep air moving around and direct it generally toward the ridge vents.

I'm no expert, and I don't mean to imply this post is fit for any purpose.

 

[jejeosborne]

I did a Google search (without quotes) of "condensation in metal buildings."

This site
Controlling condensation in metal buildings

and

This site

Design & Build With Metal: Understanding Condensation In Metal Buildings


The first site is using comparison to pregnancy. He also used an example using a soda can in front of an air conditioned vent as an example of ventilation. I don't think a/c is an option for the OP. Blow unconditioned air over the same can and more condensation would occur. Again this is what my home dehumidifier does, blows air over cold metal. The goal here is to keep the warm air away from the cold metal. I consider that example not feasible.

The second site describes ventilation similar to what I mentioned. You need to ventilate the section between the insulation and metal. To do this you would need an attic space. Your goal in an attic is to keep the temp in the attic similar to the outside. I doubt an attic is an option for the OP. Ventilation I think is still not the best answer for this particular instance unless there is a source of moisture inside his building like livestock or he is making moonshine.

Basically he needs to separate the air from the metal. Simple but somewhat expensive. I have the fiberglass wrapped in plastic and it is only about an inch thick on my ceiling and I get no condensation. The plastic conforms to the contour of the metal and the seams are overlapped and sealed. A ridged insulation would have to be sealed at the seams very well to prevent any air to get through. Maybe the OP just needs to tape up the seams.
Jeff

 

[EE_Bota]

I did a Google search (without quotes) of "condensation in metal buildings."

This site
Controlling condensation in metal buildings

and

This site

Design & Build With Metal: Understanding Condensation In Metal Buildings


The first site is using comparison to pregnancy. He also used an example using a soda can in front of an air conditioned vent as an example of ventilation. I don't think a/c is an option for the OP. Blow unconditioned air over the same can and more condensation would occur. Again this is what my home dehumidifier does, blows air over cold metal. The goal here is to keep the warm air away from the cold metal. I consider that example not feasible.

The second site describes ventilation similar to what I mentioned. You need to ventilate the section between the insulation and metal. To do this you would need an attic space. Your goal in an attic is to keep the temp in the attic similar to the outside. I doubt an attic is an option for the OP. Ventilation I think is still not the best answer for this particular instance unless there is a source of moisture inside his building like livestock or he is making moonshine.

Basically he needs to separate the air from the metal. Simple but somewhat expensive. I have the fiberglass wrapped in plastic and it is only about an inch thick on my ceiling and I get no condensation. The plastic conforms to the contour of the metal and the seams are overlapped and sealed. A ridged insulation would have to be sealed at the seams very well to prevent any air to get through. Maybe the OP just needs to tape up the seams.
Jeff

Pregnancy...saying you either are or are not pregnant, but condensation ranges from a little to a lot, and matters a little or a lot. Also, he shows examples of tin roof covered buildings, and in my area, covering houses with metal is all the rage.

Unconditioned air blown over surface...will have the effect of making the metal temperature match the air temperature more quickly than it would otherwise. Your post #83 seems to agree, except for the cold energy part, which I don't really understand, so I cannot comment on that.

 

[jejeosborne]

Yeah bota, i was just poking fun at the first weblink. As far as the moving air warming the metal faster, I agree on metal items within the barn like tractors and tools but not on the roof. I gave the example earlier that you are going to need a lot of heat on the roof to counter the cold air mother nature is continuously supplying on the outside of the metal. I mentioned having to heat the whole county. A thermal and vapor barrier is what is needed for condensation on the roof. Ventilate if there is an interior source of moisture.

Hopefully you understand I am with you on trying to help with this problem.
Jeff