More help needed w/ pole building humidity

[jsduke]

Thanks to all who responded to my first post (drainage). All great information (love this site) /forums/images/graemlins/smile.gif .

Since it hasn't rained significantly here in a while and the floor of my building is fairly dry, I'm thinkin' I may have more work to do in addition to the drainage because the humidity is still above 90% (tractor metal always wet to touch) unless the overhead door is left open.

My building is steel clad (sides/roof/doors) with 'single bubble' insulation between roof steel and supporting wood framework. A ridge vent and soffit venting, open to the inside of building, comprises total 'planned' ventilation (no windows or cuppola). Additional air may enter where the steel corrugations stand out from the ground level pressure treated nailer.

While the tractor and other equipment inside bead moisture (mostly but not entirely on the underside) the inside of the steel seems fairly dry(?).

Any ideas on how I can diagnose/eliminate this indoor rain forest? It can't be that good for my stuff /forums/images/graemlins/frown.gif.

Thanks again.

duke.

 

[DavidJ]

You basically have 2 choices.

Dehumidifier. Which will reduce the moisture to a noncondensing level.

Power ventilation. This will be the lower cost but I'm not sure it'll completely cure the problem. I'm sure it'll help because you said it gets better with the overhead door open.

 

[BubbaJr]

I have 6" of insulation in the walls of my pole barn, and 12" in the ceiling. I still had a moisture problem and found that it was coming from the concrete (about 1-1/2 years old). I bought a dehumidifier and now everything is dry out there. Just make sure you get one that is sized for your building.
Good Luck.

 

[Junkman]

</font><font color="blue" class="small">( I still had a moisture problem and found that it was coming from the concrete (about 1-1/2 years old). )</font>

When I poured the floor in my garage & cellar 20 years ago, I put 6 mil poly on top of the gravel and have never had a problem of moisture coming up from the ground below. I did it in my latest garage floor 3 years ago and the contractor said that it is common place now to use it. The only thing is that when they pour the concrete, it must be stiffer because the moisture in the concrete will only come to the surface when they power paddle it. I does take longer to set up, but that is a plus for strength. I also finished the top surface with a clear poly sealer as soon as it was dry enough to walk on ....

 

[jmc]

I think you should start with the floor too. The old timer who is going to concrete my polebarn floor told me that the concrete sealer works so well you don't really need the 6 mil plastic underneath. Although I'm going to put the plastic down anyway, that's a pretty good recommendation for an after-the-fact fix. Cheap too. A dehumidifier would be a very last resort to me with the soffitt/ridge vent openings.

 

[Junkman]

I spilled some diesel fuel on the concrete this weekend and learned for the first time that it will dissolve the concrete sealer and make it tacky. Now I have to wash that area with a detergent and reapply the sealer. I wouldn't skimp on the plastic.... cheap insurance.....

 

[beenthere]

Adding heat to the building will help lower the relative humidity and decrease the wet condensation on the equipment and tools in the building. If you have insulation, heat will be the easiest fix available to you, IMO. Plastic beneath the slab would have been the best, but too late now.

Too many old timers say plastic isn't necessary, but they don't have to put up with the wet concrete slab either. Some who pour the concrete don't like the plastic because the concrete can't be worked as quickly so it takes them more finishing time. The last concrete I had poured, the crew put down two inches of sand on top of the plastic, holding it in place and making the concrete set up quicker for earlier trowling. Seemed to work great.

 

[Egon]

The plastic keeps the water content of the mix at proper levels. The soil underneath can't absorb any water from the mix thus making finishing time longer and requires more site time before the final trowelling.

gon

 

[jsduke]

I guess I failed to say that my floor is not concrete /forums/images/graemlins/blush.gif. The base is an aggregate/dirty fines mix (crusher run). The floor has yet to be topped with a clean fines/agg. material (several inches).

Is there some way I can place plastic down between my base and topcoating maybe using sand or stone dust to isolate the plastic from the larger aggregate below and above to prevent puncturing/tears? Maybe a very thick plastic and/or multiple layers?

Thanks.

duke.

 

[Junkman]

put down a 2" or 3" layer of stone dust and then put the top coat on. 6 Mil plastic should have enough strength to hold up. I would use concrete rather than any other top coat because of the firmness. I have found that when you park anything on a gravel or asphalt floor, that it will eventually sink into the surface.... I would also put wire into the concrete and if you are planning an apron, then put some re rod into the end where the apron is going to be and have it extend out about 2" from the edge of the floor. You can do this by drilling some hole in the wooden form to put the rods through. The only problems is that you will have to cut the wood to take it off the rods.... chances are it is only going to be a 2 x 6 so you won't be wasting much lumber.... I spaced mine 12" apart and the apron has never fallen away from the floor......