Add to that a wide ditch with either no grate or a rickety one across which each barrel must pass for washing, and you are getting the idea. We are not even considering a space with inadequate insulation from summer heat and winter cold as a barrel room of any kind. As received, barrels are usually works of art, with good looks and aromas. If sulfur dioxide is present and obscuring the real barrel aromas, simply rinse with enough water to clear it out, and re-sniff. If good sweet aromas are missing, get on the phone.
Wine barrels continue to look more like furniture if a mildewcide is applied to the exterior.
That happens to be my personal preference. While there is some controversy about the reduction in oxygen transport with this coating, I have not seen data confirming that. If so much money has been spent on this magical wooden tank, I want it to stay young and beautiful. Ten year-old barrels that have had neither mildewcide nor red wine staining are just not as pretty as I would like. Any coating that seals the barrel surface is defeating the purpose of the barrel design.