Barns and condensation.

Wakey · Apr 7, 2016

We close on this property later this month and most of our belongings will be stored in this barn while I build a new home.

I've seen people here talk about condensation yet I see no proof of it in this structure. I was wondering if this is really more prevalent further up north. This is due East of Atlanta. Does it happen during winter?

I plan on covering the floor with a plastic tarp and if it's advisable, throwing another on top of the furniture and boxes. What say you?

The barn was built in 1994 and the roof was replaced in 2011.

Also, check out the LP siding, will be replacing with Hardi.

Coyote machine · Apr 7, 2016

I'd use roll plastic and over lap the seams for the concrete floor. And put any boxes up off the floor and plastic, if possible, so air can circulate. Tarps are not a good water/condensation break, definitely not as good as plastic; they will leak water over time.

Air movement is a good thing to keep humidity/condensation from taking hold.
Looks like you have a dry building there. Very thin plastic can be used to cover any items that could get damaged by condensation or any roof leaks, if they were to occur.

zzvyb6 · Apr 7, 2016

Condensation forms when outside air pressure goes down. Air will find its way into your plastic wrapper, so when the pressure drops you are gong to have moisture condense out. I'd suggest also storing some very dry hay bales in there. Hay is hygroscopic: it absorbs moisture.

I's also run a full time fan in there to keep the air circulating. Is this building sealable, or is it a typical barn with access to mice, raccoons, birds and other mess makers ?

Wakey · Apr 7, 2016

I think mice can get in to just about anything. I plan on leaving a 2 foot gap between the possessions and the wall so I can monitor dCon trays and spray for pests. All the boxes will be sealed and all the artwork and prints are wrapped with cling plastic. Good idea on the pallets, I'll bring some up there.

The roof has a ridge cap, would I need a fan as well?

Wakey · Apr 7, 2016

You know, I have a squirrel cage from an old A/C unit that I can run out there. Should I rig a timer for daytime operation or run it 24/7?

Cord · Apr 7, 2016

Wakey said:
We close on this property later this month and most of our belongings will be stored in this barn while I build a new home.

I've seen people here talk about condensation yet I see no proof of it in this structure. I was wondering if this is really more prevalent further up north. This is due East of Atlanta. Does it happen during winter?

I plan on covering the floor with a plastic tarp and if it's advisable, throwing another on top of the furniture and boxes. What say you?

The barn was built in 1994 and the roof was replaced in 2011.

Also, check out the LP siding, will be replacing with Hardi.

It's a problem that really shows up in spring in Northern climates. The building, although uninsulated, tends to trap heat (or cold). First couple of warm spring days and the humidity shoots up. The floor and contents, being cold causes the moisture to condense on them. Generally if I have some warm spring days, I'll open up the doors to get the air to move through them. This helps dry up the moisture but also lets the building interior warm up faster. Once the contents warm up the issue goes away on it's own.

Mice are really bad in fall when they are looking for a place to shelter during winter. My garage up north, I can't set out enough bait blocks for them to eat. We've learned to leave nothing out that can be damaged by mice. Anything that is fabric or paper gets stored in totes with a snap on lid.

EddieWalker · Apr 8, 2016

Condensation is formed when you have more water in the air then it can hold. Air always has a certain amount of water vapor in it, even in very dry climates like the desert. In most places, its most noticeable when the air is cooled quickly and the water vapor solidifies This is exactly what happens to a cold soda can on a hot day.

Your roof has air above it and below it. The air above it is controlled by Mother Nature that heats and cools it as the day begins and ends. At first light, you will have the coldest temperatures of the day. If the air still has more moisture in it then it can hold, you get condensation. Air holding 50 percent humidity will increase to 100 percent humidity as the temperature drops. When this happens, water forms on the surface.

In barns, this happens on the underside of the metal roof. The two most common methods to deal with this is air flow, or insulation. Airflow is the cheap way. Do you have eave vents and a ridge vent? Heat rises, so a vent down low allows air to enter it, then it gets hot and it exits the highest vent. Simple, cheap and effective. The other method is to insulate the roof. If there is enough insulation, the temperature change doesn't happen.

tcartwri · Apr 8, 2016

You need to keep air circulating inside the structure. We have several seacans that we use for storage and the first spring they literally rained inside with moisture, and they obviously do not have dirt floors.

k0ua · Apr 8, 2016

The fact that your barn has a ridge vent has a lot to do with it staying dry. My "Kioti house" metal barn had a lot of condensate when first built. I since have put in vents on each end and it has helped tremendously in keeping it from raining inside.