JimReed

Humidity Control in a Steel Barn with Gravel Floor

7 posts in this topic

I have a separate steel barn adjacent to my workshop where I intend to store wood for eventual use. It has a gravel floor and the building seems damp. My thought was to install some roof vents which I know should help some but I think the real key is some kind of vapor barrier. Does have anyone have any good recommendations. My thought was to put down a vapor barrier over the existing gravel floor (#2 stone) and then put down a layer of finer gravel (#1 stone) but I don't know if this is the best way to do this or what would make the best vapor barrier. Because this is purely a utility building, I am looking for the cheapest solution to this problem.

Thanks for your help!

Jim

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I would worry more about air flow maybe using attic fans. The issue with those types of building is the rapid temp changes. For example if its cold in the morning but starts to warm up and you swing open a door there is a rapid temp change causing the release of moisure. The idea is to just keep things dry and the temp changes sloooooow. Attic fans on a timer are plenty for pole barn type building. The floor will stay dry as long as its not getting flooded from the exterior. Look at your run off and correct as needed.

Don

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Dwacker, are you saying forget the vapor barrier altogether? But you are exactly right about the rapid temp changes causing the problem. Here in Upstate NY we can have frigid nights and warm days so when you open up the barn mid morning, humidity instantly condenses on anything metal. Because of this, I worry about what these huge humidity swings might do to my wood.

My barn (1,100 sq ft) is just steel with 16' high ceilings and 12' doors on each end. Currently there are no vents or fans. Does anyone have any recommendations for the optimal venting/fans for this size area or do you know a resource where I can compute these needs?

Jim

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Dwacker, are you saying forget the vapor barrier altogether? But you are exactly right about the rapid temp changes causing the problem. Here in Upstate NY we can have frigid nights and warm days so when you open up the barn mid morning, humidity instantly condenses on anything metal. Because of this, I worry about what these huge humidity swings might do to my wood.

My barn (1,100 sq ft) is just steel with 16' high ceilings and 12' doors on each end. Currently there are no vents or fans. Does anyone have any recommendations for the optimal venting/fans for this size area or do you know a resource where I can compute these needs?

Jim

I would not put down a vapor barrier. Lowes has some decent attic fans, personally id just put one in each gable. They are rated pretty high so two should be plenty. Just run them on timers to counter act the temperature changes.

Don

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Controlling humidity can be tricky business and I would definitely research this best you can. From my understanding, you have to either stop the source of moisture getting into the building or control condensation by maintaining a level of temperature above dew point. Ventilation also comes into play depending on your situation with materials and environment. http://www.buildingscience.com/ might have some info to help you out. It's kind of confusing to figure out the best solution and I don't know if it's going to come cheap. I have heard of some people insulating their steel buildings with Prodex and they seemed happy with the results. Mostly from a temperature point of view. Not sure about humidity levels. Here's a link to the Prodex product http://www.insulation4less.com/Insulation4lessProduct-19-Prodex-Total-16-inch.aspx They might also be able to help you out with some info. Hope this was of some help.

Art K.

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As this is a barn and not an enviromentally controlled enviroment I'd say that stickering and piling your wood in an area that has plenty of air movment is the key. Stacking your wood on the north side of the building to avoid radiant heating then cooling throughout the day/night might be an idea as well.

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Drystack your wood and provide lots of airflow and make sure it does not receive any direct mosture such as rain etc. Thats all you need to do. Doing this will ballance it to the levels in your region.

As for your floor. An exposed gravel floor is a very high source of humidity. It retains moisture and will only serve to prolong your high humidity levels. Basicall it is dirt. It dosn't retain as much moisture as top soil but it still does retain a lot. If you install enough fans for the size(volume) of space you have you will reduce the levels of humidity in the room as much is allowable in your particular climate. To reduce the levels further you need to seal the environment and condition the air either by heat or cooling depending on what season it is.

If this is a utility building then leave it as gravel and provide good ventilation. Remember your lumber being stored in your utility building is better than the sawmill that sawed your wood. Sawmills store their wood outside with tarps on them for the most part. Some have storage areas with a roof over them but the sides are always exposed. Seems to have worked well this way for 100's of years so why try to reinvent the wheel.

I grew up with my family owning a sawmill & logging. We would saw cedar and birch almost exclusively. We dry stacked all our wood and left it outside covered with a roof overhang then later just outside with tarps. Thats how we dried all our wood. Worked perfect!

If it ain't broke don't fix it!!!

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