Originally Posted By: dhartke
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Last week I inspected a 3 year old home built on a concrete slab that has a tornado shelter beneath it. The shelter is 6’ X 12’ X 4’ high. Entrance is by a solid trap door. The only ventilation is by a 4" PVC pipe that penetrates one wall and terminates in the attic. The walls, floor, and ceiling are poured concrete. Perimeter drainage is adequate.
The floor is covered by 1/4" or less of water and the walls are all damp (looks like concrete when the forms are first removed), increasingly the closer you get to the floor. No obvious isolated point of water entrance or cracks or honeycomb concrete. I reported "the shelter is damp" and "the owner states it has always been damp" and "UGL Dryloc may prevent further water seepage".
The buyer has requested a cost estimate to apply UGL Dryloc. I now wonder if indeed the dampness is from condensation instead of seepage. The air is stagnant except for the 4" pipe vent. Can condensation occur to this extent in an almost air stagnant space? Can the concrete walls allow the transfer of that much water?