Condensation Inside New Shed

Old 02-17-18, 08:44 AM
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Condensation Inside New Shed

I recently had a 10x20 Prairie Built barn delivered. The barn sits on a gravel pad.

I store my motorcycle in there and I have noticed condensation on my bike. I'm concerned where the condensation is coming from. Could it be moisture leaching out of the wood? The shed has vents on each end at the gable.

Thoughts would be appreciated.


Old 02-17-18, 08:48 AM
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The shed stays cold while it warms up outside. So the humidity from the outside air condenses on the cold objects inside. Same reason a car has frost or dew on it in the morning.
Old 02-17-18, 09:34 AM
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Would insulating the inner walls with foam board help cut down on moisture?

Its been really wet wet around here lately so may not be much that can be done short of heating the building.
Old 02-17-18, 09:51 AM
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You could run a fan to move out the moist air.
Old 02-17-18, 09:59 AM
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Is there a floor in this shed?
If not it could be a large part of your problem.
Is so then possibly humidity from the air is condensing on cold objects at night.

Insulation could help but exposed foamboard would be against fire code if you are concerned about this.
You could also increase the size of the vents to allow moisture to escape.
Old 02-17-18, 10:01 AM
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I'm not personally familiar with the climate in Ohio but I agree moisture may be moving into the shed. So, while I agree with XSleeper as a general matter, I'd focus on reducing the moisture inside through ventilation. Your shed (like most) has a passive ventilation system, meaning you're counting on the vents to passively move air. While this is perfectly OK, it's hit-and-miss as the vents may or may not be venting adequately. My suggestion is to do nothing this winter. But, if the problem continues enlarge the ventilation.

BTW, you say nothing about the floor. please let us k now what it is and how it was done.
Old 02-17-18, 10:36 AM
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The barn sits on a gravel pad.
Adding foam to an unheated building will keep the cold temperatures inside the shed longer each morning... while the outside warms up. This would prolong the amount of time there is a large temperature differential. It's the temperature differential that provides the conditions for the dew. For insulation to help, you would need to be heating the shed. Then the insulation would help keep the heat in. Insulation alone does not make something warmer.

On a car that sits outside, the sun and wind combine to evaporate that moisture away. Inside the shed you have no sun, no wind, no heat source other than the ground (if it's not frozen) or the sun on the outside walls and roof.

So unless you plan to heat the garage, ventilation is about only thing you can control. Blowing outside air in could possibly make the problem worse by introducing warmer, more humid air into a cold room. But eventually the air movement would win out since it will equalize the temperature inside/outside more quickly than if you did nothing at all.

Rather than blowing warm air in and cold air out, I would probably suggest you first try to just keep the air moving inside the garage with a fan, and see if that helps.

Otherwise, the roof of your building likely warms up the fastest, so if you used a fan to mix the air up high with the air down low, that might also reduce the amount of time it takes for the dew to burn off.

Since you say the barn is setting on a gravel pad, the ground itself can be a large source of moisture.
Old 02-18-18, 05:30 AM
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Bottom line, in an unconditioned space you are subject to the elements.

My current garage which gets a little heat off the adjoing house is like that, when we start to get warm spring weather and the foundation , tool boxs and cars are still cold everything gets wet.

About the only think that helps is to keep the vehicles covered but it's a small imporvement,
Old 02-18-18, 06:11 AM
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I would suggest a moisture barrier, a plastic membrane (6 Mil+), below the gravel on the floor, unless one was installed before the gravel was laid down.

But with that barrier comes the need to make sure that no moisture, rain, snow or ice, is allowed to enter the gravel from above; as it will just come back up.
Old 02-21-18, 12:16 PM
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I agree that a moisture barrier under the gravel may be all you need. Make sure you sufficiently lap it up the sides to prevent any ground water from seeping in. I have 30 year old dilapidated piece of crap wooden shed with no ventilation and a wooden floor and have never had any moisture issues.

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