I am giving my wife a hug in the kitchen a couple of nights ago and while she's looking over my shoulder spouts out, "What is that brown spot on the ceiling?" I could feel the hairs on my neck standing up... shivers down my spine. I know what's above us... and I KNOW what a brown spot on the ceiling means.
I rush up the stairs, run into the bathroom, opening the vanity doors. Inside, it was wet. Small puddles of water on top of my wife's yet-to-be unpacked cosmetic items. In the center of it all was a small generic brand of baking soda. It was totally drenched with water. You could squeeze it like a wet sponge. Surrounding the baking soda box, the boards making up the bottom of the vanity were soaked too.
As in the mouse post, I took apart the floor of the vanity, coming to the screwed down board again. This whole board was soaked as well. Opening it up, I can see the lath below... wet. Well, now I am seeing the "brown spot" from above.
So what caused this water staining on our plaster ceiling? I can only make an educated guess. You see, we took our showers in the morning, humidity remained in the bathroom, like it has previously. We used the sink like we have previously. Yet, the staining was seen at least 8 to 10 hours later on Sunday, after three full weeks of the same daily humidity levels. There are no real leaks coming form the sink. At least, none that could cause this level of staining. I ran the water for several minutes on hot, cold and warm. I filled the basin up, allowing water to enter the over flow (as recommended by a forum). No leaking. Then I did a tissue test (also from a forum). I ran the tissue around the valves, drain pipes, etc. as the water was running. There was a small leak from the cold water valve, but honestly, if this were the cause of all that water, then I must have the biggest shut off valve in the world. There's no way that a drip an hour (if that) could cause that much staining. The photo below shows the water droplet forming under the valve behind the handle.
So what changed that could have caused this level of water accumulation?
Here's my educated guess. My dear wife, wishing to rid the bathroom once and for all of the smell of death left by the home's former owner, purchased and placed a small box of baking soda under the vanity, directly over the screwed down board. When the humidity built up in the bathroom, it super saturated the baking soda and as we do not have a vent fan to rid the moist air, the little box of baking soda did the best it could. It sucked all the moistness out of the air... until it could no more (poor little guy). The wooden panel underneath the box began to absorb the moisture from the baking soda... then the baking soda started to pull more moisture out of the air... thus a cycle started. Taking several hours, it slowly wetted the ceiling below causing the brown staining.
OK, seems a bit far fetched, but can you do better?
11/17/2011: Update
Seems as though the valves under the sink are leaking, especially when they are on full open... I have a tray under the sink to catch any additional water leakage, but so far none as I have turned the valves back to less than full open.
