Metal Building Condensation

[Friartuck]

Trying to assist a fellow car guy in diagnosing a severe condensation problem.

1. Metal building erected two years ago on slab. Size is 18 Wide X 35 Long X 12 High at the roof peak.
2. Dry unpainted concrete floor
3. Rigid foam insulation on walls and ceiling (under roof line)
4. Kerosene heater keeps temp at least 40 degrees.
5. Location is NJ, first real cold weather past few weeks.
6. Condensation is so severe its weight is pulling down ceiling insulation boards and puddling on the floor. Seems to occur at front half of the building, the side with the garage door.
7. Single insulated overhead door.
8. Problem just started when it got really cold, say under 40 and below.

What is the cause and what is the remedy?

 

[lakeroadster]

Relative humidity and kerosene Heaters: Thus, water vapor buildup in the enclosed home can create problems with condensation, molds and mildew.

http://www.oldhouseweb.com/how-to-advice/kerosene-heaters.shtml

I think for every gallon of kerosene you burn you are adding a gallon of water to the air...

 

[cybrdyke]

Yep. The heater.
CD

 

[KenB]

Double yep. Physics 101: The products of combustion are carbon dioxide and water vapor. Solution is a dry heat.


Ken

 

[Friartuck]

Thanks guys. I knew coming to GJ for this problem was the best bet. The collective knowledge here is incredible.

 

[850xpeps]

Taping the insulation joints to stop the vapour transfer to the cold tin might help a bit but ya heater is most likely the xulprit

 

[Selo]

Friartuck,

It does not sound to me that the insulation is installed correctly to prevent heated air from contacting the cold sheet metal of the roof underside. It sounds like the garage has an insulated ceiling, but not an insulated metal roof. Until that is corrected I don't think another source of heat is going to stop the condensation. Heated uninsulated metal buildings sweat no matter how they are heated.

Could you post some pictures?

Selo

 

[finn]

High school chemistry lesson.

Upgrade to a vented heat source.

Your ears will thank you too, once you ditch the noisy torpedo heater

 

[Kpaige]

Yes change to a correct heater. But hot air contains moisture. Moisture vapor will turn back to water on contactcwith a colder surface. Instal proper insulation on the walks and ceilings with at minimum a 6 mil vapor barrier with fully taped seams!
It will cost less to heat and no more rusty tools!

 

[Radix2]

Friartuck,

... Until that is corrected I don't think another source of heat is going to stop the condensation. Heated uninsulated metal buildings sweat no matter how they are heated.

Yes change to a correct heater. But hot air contains moisture. Moisture vapor will turn back to water on contactcwith a colder surface.

This is not true.

What you are both missing is that cold winter air (due to it being cold - cannot hold much water) - so heat that winter air up, and the relative humidity plummets. This reduction in relative humidity due to heating is why humidifiers are often used in the winter.

If you have a correct heater that vents wet combustion gasses outside, you should expect very low humidity inside a heated building in the winter time - if there is condensation it will be from things like - melt water from cars, cooking, showers, moisture from slabs, breathing, etc.

 

[Kpaige]

It is true.
I have seen many buildings that run dry heat condesate. Just because the relative humidity is so low that we need humidifiers for comfort does not mean the heated air does not contain moisture. Its just not enough to be comfortable to humans.
65 in the house zero outside dry as dry can be if you allow that warm air to settle on the cold metal roof it will condensate period!
I fix these issues for a living. Proper vapor barrier, proper insulation, and proper ventilation is the only solution.
Use my info if you want.

 

[Radix2]

It is true.
I have seen many buildings that run dry heat condesate. Just because the relative humidity is so low that we need humidifiers for comfort does not mean the heated air does not contain moisture. Its just not enough to be comfortable to humans.
65 in the house zero outside dry as dry can be if you allow that warm air to settle on the cold metal roof it will condensate period!
I fix these issues for a living. Proper vapor barrier, proper insulation, and proper ventilation is the only solution.
Use my info if you want.

OK, I see what you are talking about now. You are right, you can't let your interior air contact uninsulated surfaces for a variety of reasons including this one.

His immediate problem here is venting the combustion inside.

 

[Kpaige]

Agreed

 

[Selo]

This is not true.

What you are both missing is that cold winter air (due to it being cold - cannot hold much water) - so heat that winter air up, and the relative humidity plummets. This reduction in relative humidity due to heating is why humidifiers are often used in the winter.

If you have a correct heater that vents wet combustion gasses outside, you should expect very low humidity inside a heated building in the winter time - if there is condensation it will be from things like - melt water from cars, cooking, showers, moisture from slabs, breathing, etc.

Not missed at all...You make a good point re cold outside winter air. Yet how many of us have buildings where there is no "melt water from cars, cooking, showers, moisture from slabs, breathing, etc". With all due respect the answer is none, thus any heat source in an uninsulated building will promote sheet metal sweat.

Cheers, STJP

 

[Selo]

It would be nice if the original poster could clarify his insulation installation and post a pic or two. Lots of interested experienced folks here willing to help.

Selo