Marks on the wall

Pingu1

I have discovered some brown marks on the wall in the communial area of my block of flats, next to the back door. I'm worried it is water marks. They seem to be on the lower part of the wall. The ceiling looks fine and there are no marks in the area directly above on the first floor. I have noticed a smell in the area in the past although it was fine today. The first picture shows the marks, the second one is the ceiling, the third one is the outside and the fourth photo is the area directly above on the next floor. If water was coming down from the roof, why would it only appear on the lower wall? There is another property next to the wall, could it be from there? Can anyone advise? Thanks.

WIAWSNB

How wide and high an area is affected?

When did you first notice it? Did it appear suddenly, or develop over time? What's the smell of?

I would agree it is liquid forming to the extent it is running in rivulets down the wall. Possibly it's water, but is coloured by picking up dirt on the wall as it forms. Possibly someone sprayed or spilt something there - if it appeared suddenly.

It doesn't look as tho' it's come through from the other side, tho' I guess that can't be fully ruled out (it wouldn't make sense for it to look like this, I don't think.)

Who is responsible for communal cleaning?

If you wanted to, you could clean just one vertical strip in t'middle a foot wide, and monitor it for return. That should answer a few Qs.

Blue_Doggy

Does anyone who lives in your block have a dog which comes back muddy and wet from walks and shakes itself when it has come in through the back door? That could be the cause. An enthusiastic shake by even a moderately hairy dog can go far, even making the odd splash on the ceiling.

How are the communal areas serviced or cleaned? Is there a contracted cleaner or is it the responsibility of the owners of the individual flats?

born_again

Someone left or kept the door open, when raining?