A few months ago I noticed a small water stain appearing where a
plaster crown molding meets the ceiling. Recently I noticed a
dripping noise after I shut off a sink in a bathroom that's more or
less above the stain. I might not have noticed it sooner because
there's usually a lot of noise from the bathroom vent fan.

Before I call a plumber or have the ceiling or wall ripped open, I'd
like to find out if the drip actually indicates a leak, and not just
normal water draining through the drain pipe. If I run the sink for
10 seconds, then shut it off, the dripping starts about 15 seconds
later, and continues for about another 15 seconds, at a rate of about
3 drips per second. I can hear it from the bathroom as well as from
the downstairs room. The plumbing is about 20 years old, in a house
that's much older.

Are there any tricks to find out what's going on?

Jimmy

wrote:

A few months ago I noticed a small water stain appearing where a
plaster crown molding meets the ceiling. Recently I noticed a
dripping noise after I shut off a sink in a bathroom that's more or
less above the stain. I might not have noticed it sooner because
there's usually a lot of noise from the bathroom vent fan.

Before I call a plumber or have the ceiling or wall ripped open, I'd
like to find out if the drip actually indicates a leak, and not just
normal water draining through the drain pipe. If I run the sink for
10 seconds, then shut it off, the dripping starts about 15 seconds
later, and continues for about another 15 seconds, at a rate of about
3 drips per second. I can hear it from the bathroom as well as from
the downstairs room. The plumbing is about 20 years old, in a house
that's much older.

Are there any tricks to find out what's going on?

Jimmy
\

If the 20 yr old plumbing was done in PVC, dripping noises
are common and may not indicate a leak.

A stud finder can be useful in locating wet plaster
since it appears denser than the surrounding dry plaster.
Try it.

An Ohmmeter might be used with a pair of probes to detect
areas of lower than normal resistance. Takes some experimenting.

Touching the suspect area with the back of the hand can sometimes
show up moist spots from the feel of it.

Jim

wrote:
A few months ago I noticed a small water stain appearing where a
plaster crown molding meets the ceiling. Recently I noticed a
dripping noise after I shut off a sink in a bathroom that's more or
less above the stain. I might not have noticed it sooner because
there's usually a lot of noise from the bathroom vent fan.

Before I call a plumber or have the ceiling or wall ripped open, I'd
like to find out if the drip actually indicates a leak, and not just
normal water draining through the drain pipe. ...

The water stain indicates a leak.

Whether it's actually the drips hitting the ceiling or inside the drain
is of little consequence; the leak needs fixing.

As another poster said, investigate for dampness in the plaster and the
ceiling area. If it is drain rather than supply, not using the suspect
sink for a while should allow it to dry completely whereas a supply line
leak would continue.

--

On Sep 23, 4:57 pm, dpb wrote:
The water stain indicates a leak.

Whether it's actually the drips hitting the ceiling or inside the drain
is of little consequence; the leak needs fixing.

The thing is the dark area on the ceiling is so small and slow-growing
that I'm not even sure it's a leak. It's maybe 6 inches long and a
quarter inch wide, along the edge where the ceiling meets the molding.

As another poster said, investigate for dampness in the plaster and the
ceiling area. If it is drain rather than supply, not using the suspect
sink for a while should allow it to dry completely whereas a supply line
leak would continue.

How long should I avoid using the sink to wait for it to dry?

I think the drain pipes are PVC, but if they're copper, does that mean
a dripping noise definitely indicates a leak?

Jimmy

wrote:
On Sep 23, 4:57 pm, dpb wrote:
The water stain indicates a leak.

Whether it's actually the drips hitting the ceiling or inside the drain
is of little consequence; the leak needs fixing.

The thing is the dark area on the ceiling is so small and slow-growing
that I'm not even sure it's a leak. It's maybe 6 inches long and a
quarter inch wide, along the edge where the ceiling meets the molding.
....

What else do you think it might be? Even if it's mold/mildew that would
be indicative it's damp.

Get up there and see if the spot is damp to touch, slightly softened if
actually plaster, etc., ...

The drip may or may not be inside the pipe; there's no way to tell from
here as I can neither see nor hear it to judge.

If it's actually the water dripping on the upper side of the ceiling it
may be possible to tell that by being close and listening carefully--the
old mechanic's trick of the screwdriver touching the wall and using it
as a stethoscope might help locate it if so.

Drips inside drains can occur w/ either Cu or PVC. If it's been a long
time in the house and never noticed it at all until recently, it's
likely a new symptom.

How long before the area dries out if damp would depend on many factors
but I'd think a week would make a difference that should be discernible
at most if it's significant at all...

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