We live full time in a 35" fifth wheel. The area under the bathroom sink has a 14 x 14 laundry chute opening to the storage area below. The plumbing drain vent is also located underneath the sink. All this is enclosed with the cabinet around the sink. We currently are staying in an extremely hot & humid climate (Louisiana Gulf Coast). Our problem is the underneath side of the sink is allowing condensation to form on the sink bowl. This caused a mold issue in the area under the sink before it was first discovered. I have since closed off the laudry shoot opening and cleaned the walls of any mold. My theory is that either the moisture from the hot air in the storage area or from the drain vent is condensing on the much cooler sink bowl. We keep the inside temp around 72. Has anyone else seen this problem occur? If so how did you correct it? I am thinking of removing the sink and trying to find some kind of spray on material that can be used to insulate the bottom of the sink. Does anyone know of such a material? Hot in La.