Condensation in my bus shed.

[bevans6]

I have a steel sided frame building to store my bus in in the winter.  I'd keep it in there in the summer too, but there is a problem with condensation...  I literally have puddles on the floor under anything over 3" square, and I've seen it literally drip from the ceiling.  Here is the deal - it's a frame building, 6" stud walls 12 feet high with an engineered truss ceiling/roof, full span.  It's roughly 60 feet by 50 feet, and there is R-20 insulation in the walls and ceiling with vapor barrier plastic.  The floor is a concrete slab.  There is little to no ventilation in the attic, there is very little ventilation in the building itself unless I open the big sliding doors.  On a warm day like today (for here at least) the temperature inside the building is around 20 degrees cooler than outside, and it's very humid so I get the condensation because the floors are below the dew point of the air.  My goal is to let it get a bit warmer and find a way to get air circulation so I can get rid of the dampness.  My first thought at this point is to remove the R20 bat insulation in the ceiling so the air can circulate, and open up soffit and peak vents in the roof.

Anyone have any experience with these large buildings?  Any ideas that don't involve air handlers and dehumidifiers are what I am looking for...  I won't be heating the building in the winter, so there is little need for the insulation.

Thanks, Brian

[bobofthenorth]

I've seen some pretty effective passive ventilation systems.   If you can set up a chimney that gets natural heat you may be surprised how much air exchange you get.

[chessie4905]

 Ventilate your attic.  Also, I use a dehumidifier in the summer months, just to keep the humidity low. It doesn't cost that much and takes care of times when I have to open the door/s to move something in and out. Never had drips from ceiling; 48X60X15;10 inches in walls and 12 inches in ceiling, 6 inch concrete slab. Feels like AC in summer if I keep the doors closed. Dehumidifier raises inside temp about 2 degrees, but It is still more comfortable in there than without and covered full length pit doesn't smell funky either. I just leave it run over the floor drain so I don't have to dump the condensate container.