The floor and the walls of our shower are tiled. The valve and lever (Delta Monitor) are on a wall shared with the living room . The shower head is on a perpendicular wall and is also shared with the living room. I noticed water marks on the wooden living room floor. I removed the coverplate from the valve and shower head, wrapped paper towels around any accessible pipe joints and opened the valve to cold and hot and NO dampness was found on the towels. Our house is 8-yrs old and is built on a slab and there is no access panel. I would have to tear out the living room wall to see the pipes beyond the joints which are visible through the holes cut in the shower tile. I checked the tile grout joints and found missing grout around the floor drain and a few 1/4 inch areas of missing grout on the wall. Is it likely this could have caused an area of discoloration in the wood 1 foot by 5 ft long? I regrouted the entire shower in the hopes of curing the problem. I went in search of a moisture meter to compare before- and after-repair dampness, but they don't sell them locally and the online models are very expensive. How can I tell if I fixed the problem short of waiting to see if the living room floor rots? What next? You need to add a praying hands icon.