Reducing moisture in a pole barn??? Vapor barrier???

I have a new pole barn which I will use for cold storage of machinery. Someday maybe the front will have some concrete, but for now it will be dirt/lime/or rock. My question is - would a vapor barrier under some course lime or rock chips reduce the moisture and subsequent dripping from the roof??? How will course or waste lime hold up??? What about small rock chips??? Is any one of the two better??? Course gravel like road stone would probably be hard on a vapor barrier. I do have the grade elevated to eliminate water coming in. Eventually the building will get gutters as well. Guess I am leaning towards putting down some waste lime over a vapor barrier. Any comments or ideas. Building is 50' by 88'.

The vapor barrier should have been on the roof the floor will be fine with anything.

Sounds like you built the building in a low place. Mine is elevated and it stays bone dry except for the outer edges when it rains hard. I think if you add in a few inches of gravel that should do it. You could even lay some polyethylene plastic under the gravel.

Saw this in a friend's small metal shed.

Some pole barns in my area have shingles, eve and ridge vents to prevent condensation on roof.

At night roof is exposed to sky and cools below dew point, water condenses inside and outside on the cold steel. You can dry the air out somewhat with vapour barrier on floor but if is very cold out or clear sky it will still condense.

I am going against the crowd here, but a I think a vapor barrier underneath will help. I put a vapor barrier underneath the concrete in my barn, and I noticed that stuff doesn't rust much now. I previously had a dirt floor, and everything rusted quickly. The earth has a lot of moisture, and it wicks upward. I am on a high point, and have very sandy soil. I guess I can say that a barrier underneath concrete will help?

From your comments it sounds like the building is already built. If not seriously consider adding insulation under the steel corrugated metal roof sheeting. The metal cooling and the subsequent moisture condensation will be your problem. When I built mine 1 1/2 or 2 inch insulation was added to the roof. It was some of the best money spent on the building with absolutely no condensation. If your plans ever progress to using part of the building for a heated shop the insulation is already in the roof. The other thing with preventing/eliminating condensation is air movement/circulation. That is another issue that needs to be addressed.

The last 2 sections of pole barn we built has the white/silver bubble type barrier with the white side facing the floor. With cattle in it year round you never see a drip. In the older building with bare steel when the frost underneath melts it's almost raining indoors

I have a dirt floor shed where moisture was a problem.
I put in a lot of drain tile around the building to stop water migrating underground underneath it.
I had a vent in the peak, but wanted more.
So, I made a pipe 'chimney' attached to the vent hole so it would 'draw'
Helped a lot.

I think the vapor barrier in the floor is a good idea, stop the moisture from coming in. The condensation stop under the roof steel is also a very good idea, but it's best to stop the moisture from coming in. It would be best to have sand under and over the poly to prevent puncture. We have poly under our floors and our sheds are dry.

When I built my riding arena, I put osb down, then 30# roofing felt, and steel on top of it. No moisture problems from the roof. The portion that has concrete floor has moisture barrier under it, slab does not sweat either. The extra cost of the Osb board and roofing felt was well worth it to me.

Wont work. Everytime the air is humid and the steel is cooler than the air you will have condensation. The time to plan was when you built the roof. You needed wood, then vapor barrier, and then steel. I did this with good venting. My walls condense, roof never.

I put up a 60x80 and don't have any problems at all.Did you put Sheeting under the roof tin?

(quoted from post at 12:57:11 08/02/17)
I am going against the crowd here, but a I think a vapor barrier underneath will help. I put a vapor barrier underneath the concrete in my barn, and I noticed that stuff doesn't rust much now. I previously had a dirt floor, and everything rusted quickly. The earth has a lot of moisture, and it wicks upward. I am on a high point, and have very sandy soil. I guess I can say that a barrier underneath concrete will help?

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I agree, Spook. We did the same thing in our barn, put compactible fill, then vapor barrier then concrete. I truly believe it stops the moist vapor from wicking up from the earth. We have a high water table and before the concrete with a heavy rain the water would rise up and have a mini flood in the lower end of the barn. My barn (built 1902) has a metal roof and we don't get condensation in it, have plenty of ventilation however. This is even with animals in the building.

At the other place we had the same vapor barrier on the floor under the concrete and the metal roof was insulated, and animals inside. No condensation issues there either, but again lots of ventilation.

Hadn't been following this thread, but let me first say that BOTH ways of thinking are correct.

We live in a wetlands area and have some outbuildings with concrete floors. Can't tell you how many times I've gone out and the concrete is saturated with water! Also, the ground is soft and every time you take a step, you leave a wet footprint behind. So if the water table is high enough, not even concrete will prevent the upward wicking of moisture! Poly sheeting in the floor will definitely help, but avoid having rock with sharp edges as it will puncture the sheeting over time and you'll be almost back where you started, except that the now-leaking poly will retard the flow of moisture in BOTH directions! If you have rain/snow that gets inside, it will then have a more difficult time draining into the soil with the poly barrier there.

The advice about condensation on the ceiling is also spot-on. I had set up a small, portable building one winter to keep the truck parked in. I figured it would save be having to brush the snow off every time. Well, that part was correct, but there was another problem instead. As the temp inside the building was warmer than outside air temperature, melting snow and ground moisture would evaporate, then condense on the uninsulated ceiling of the tarp-like fabric. It would continually build up, then rain down on the truck. Ended up spending a lot of time chipping/scraping ice away!! Needless to say, I started parking outside after that, just like usual. Sure was glad I didn't have any open tools left in that place!

Ventilation is probably going to be the key element here. If your building is ventilated, then the outside and inside temps should stay relatively close to each other. Yes, there WILL be times when the outside temps cool down so quickly that condensation will still form, but the more the building can breath, the less you have to fear from water staying any longer than necessary.

You never mentioned how high your water table is or whether the pole barn is on high ground, so I'm going to guess that you fall into the majority, which is NOT like us with our extremely high water table. Ventilation will be the key to the overall health of the inside of the building and anything stored in it, but I also like the suggestion of insulating the ceiling of your pole barn!! Not just any insulation will work, though. If you use blown-in (cellulose) or batt (fiberglass) insulation, it's simply going to get wet and hold water, which will cause even more problems! Best thing would be to have a spray foam insulation company come and spray the ceiling. If you could afford it, would also help to spray the walls as well. If you do this, THEN adding poly in the floor will nearly stop any and all moisture problems you may have. The spray insulation will help prevent leaks, will STOP the condensation, will regulate the temperature moves in the building, and will make the building much stronger as it sorta glues the metal sheeting together. It will also make the building much quieter inside. It also adds value to the building if you should ever move or choose to convert the building into a workshop. Be sure to include ventilation, with the vents near the peaks of the building, or use a continuous ridge vent along the top.

Vapor barrier the floor, and insulate at least the roof.
My brothers 24' x 80' barn with the roof going on with insulation.