Plumbing in the Home/water stains.hidden leak?

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QUESTION: Jay:

I recently moved into a house with virtually pristine palster throughout.  There are, however, two porblem spots.  One shows yellow leaching throhg the palster, but the spot is not wet and the palster is not soft, and there is no sign of leaking in the bathroom or laundry room above.  The area above the leak was remodeled  Could this recurring stain be from an old leak that have chabged the composition of the plaster?

The other spot is even stanger.  The spot is also under a bathroom and is shaped as if liquid was poured onto a flat surface and allowed to run, but the spot is not discolored or wet and the line patterns (ridges really) are raised and rock hard, almost as if someone had dragged a finger across wet plaster, made raised ridges,  and allowed them to dry.  Any idea what this is or what caused it?

ANSWER: Bill  check above the stains. Could a toilet or tub overflowed or something like that? Are both stained areas on a ceiling or is one on a wall?. If a wall, is there a chimney behind the wall? It is possible the stains are from a previous leak especially if they are dry after constant use of the fixtures. Buy a can of spray stain killer that is oil based like Bin or Kilz and paint it then watch it for a few weeks if nothing appears  or gets wet than I would say it was a previous problem that was fixed. Sand down the areas and finish coat it. Also, don't rule out a roof leak where the vent pipe penetrates the roof. water could be following down the pipe when it rains then dries up. Check the roof flange for cracks. I have seen this several times. Good luck
J

PS if the stain is on a wall that covers a chimney, check the flashing on the roof. If you have a new furnace or boiler, make sure the installer lined the masonry chimney with a stainless line to thwart condensation if you have one

---------- FOLLOW-UP ----------

QUESTION: Jay:

Both problems are on the ceiling, and yes a tub or sink could have overflowed at some point befor I moved in. So you are saying that both areas described (even the ridges) would be water damage and since there appears to be no active leak that I can find these sorts of problems can appear well after the original leak if they were not properly fixed (kilz, etc).  The key point here is that the yellow stain is not wet, and I stuck a pin in the ridges which also revealed no concealed water.  The ridges are hard like the rest of the palster only they aqre raised like a 3D topical map showing mountains.

Bill

Answer
Bill, I'd say the key here is that they are dry. That's definitely a plus. I would go ahead and refinish and keep an eye on it for awhile. The ridges are puzzling, perhaps a poor repair job?? Anyway, hopefully any previous problem seems to have been corrected and a little cosmetic work is all that's needed.

Plumbing in the Home

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Jay Nicholas

Expertise

Plumbing & Heating (warm air, hot water & steam heat)

Experience

40 years in the business, 35 years as a lic. master plumber in NY State. Retired

Education/Credentials
Graduated Magna cum laude at the School of Hard Knocks

Past/Present Clients
Commercial, residential and light industrial. You name it ...I have probably worked on it

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