I have a 5 year old semi detached. The upper level wall between the second washroom is showing water dripping from top (near the vent pipe).

Upon climbing into attic, there is absolutely no leakage from roof, There are some traces of water near the exact location of dripping. The insulation in the area closer to the water seen was a bit black, but not moldy.

However, I have no clue of the actual source of water.

Some facts:
I don’t have a central humidifier, though I use a room humidifier
I do have laundry upstairs
Hot water usage is only in mornings and evenings.
The leakage has no pattern (I couldn’t relate to laundry/ wash/bathroom usage)
Happens once in 2-3 days and 1 drop per three seconds for few hours and then stops (completely dry).

Is it local condensation while venting?
Could it still be roof?
Some insulation that needs to be fixed?

Please help.

Pantar

If there is a leak in side of a wall, there is water or condensation that is taking place within the wall space. It could be worse, because you may also have a persistant leak, which will ultimately show up as a major problem.

So, do not hesitate to find the stud spacing and cut the gyprock that is covering the wall, exactly where the leak is taking place. It could be a neat cut and refit and a small expense to patch up the Gyprock with Polyfilla, just as this is written. Later on it could end up costing you a whole lot more if not investigated and fixed immediately. If it is nothing, then leave it open for few days and observe the leak and the quantity and the patern, with times. You might hit the right cause and eradicate it completely. Have a laugh and call it off.

These are investigative techniques and follow it to a "T" and find the RIGHT solution and FIX IT, till it is no longer a problem.

Freddie.

Hi Freddie,

I did cut the gyprock/drywall at the leak location. And as you suggested, I did that to prevent further damage, since the water could show up on the kitchen ceiling in the lower level leading to further damage and expenses.
There is a Black vent pipe very close to the origin of the leak running from the upper level to the roof. There are no cold water pipers at the leak area.
Below is a sketch of the opening showing the black vent pipe (shown as Vent pipe), Studs (shown as ||) and the drops of water (shown as 0). The Vent Pipe is completely dry the water dropd orgin is from the top.
_______________________________________________
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
|| (Vent pipe) 0 ||
_______________________________________________

The shower lines for both the upper level showers are on the opposite wal. The only water pipes running on this wall are 2-3 studs away feeding the washer.

I am planning to go again into Attic. Please advise what specifically to look for and /or any other techniques to use for.

Thanks
Pantar

The sketch or the drawing that you have posted was not very much enlightening. So, you are on your own.

But the spot where the leak is in the wall that you have cut open and left it for further investigation. So, observe the spot to see if it gives you any more clues. Keep a constant eye on it till you resolve the situation.

Sitting far away from you, I am not able to envision an immediate cure. So be persistant in your attempts and resolve your problem as soon as you hit it.

Freddie.