Hi Friends,

I have a town home, and a few weeks ago I noticed a water spot/stain on the ceiling of my second floor. The plumber said it's not related to plumbing (i.e. leaking pipe, etc.). I wonder what it could be. Anything in attic? Any idea? How can I diagnosis this? Who should I have to take a look at and fix it?

It's does not seem related to roof leak b/c there's been no rain for weeks.

Thanks much.



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You probably have to look in the attic. You
could have an animal living there. Do you have
an air conditioner on the roof?

If there is a heat/ac unit near the spot it could be condensation or pump

If no plumbing is in the area I would suspect a roof leak here in the northern states water lines are usually not in the attic/ unconditioned space

You need to crawl through the attic to the location above the stain, and try to find a source of water. The hard part can be when the water flows down from a distant source. I've seen water enter through an exposed nail hole in a shingle, flow down a rafter, drip off something attached to the rafter to a point on the plywood floor, flow across the plywood to a seam, then flow a few more inches down a rafter to create wet spot on the ceiling. A slow leak may appear weeks after rain; the spot may have been slowly soaking through the ceiling for months/years. All of this may be complicated by attic insulation, which can turn a straight dripping flow into a soggy mess.

If you can't find the source, clear away all the nearby insulation etc. and wait for rain. Sometimes you can spot a slow water flow down a rafter or roof by using a headlamp at night and looking for a shiny area.