locating source of water ingress

[diy_fun_uk]

Hi

in my ground floor flat (rented out) there's a damp patch on the lounge wall at roughly chest height. the section of wall is between the lounge and kitchen and would originally have been an external wall decades ago. at some point a kitchen and bathroom extension has been added.

one contractor is saying the cause of the damp patch is most likely a leaking rising main in the wall, however he can only see a small part of it (via ceiling hatch in kitchen and under kitchen sink i think) and would need to break into wall to properly assess he didn't actually see any water or signs of the pipes leaking.

second contractor said he didn't think it would be a leaking rising main, more likely caused by leaking external downpipe that sits in corner where lounge wall meets kitchen wall. he supported his theory by saying that's probably why expanding foam has been injected behind downpipe.

a third contractor (only based on seeing pics though) advises downpipe very likely not leaking and that foam would have been injected to compensate for gap left by smaller diameter plastic pipe compared to cast iron pipe it will have replaced. he advises water possibly getting in through poor pointing or faulty window seal or something.

for information, the damp doesn't start to dry out if there's been no rain for x days, so i reckon it's either a leaking internal pipe e.g. rising main (constant water under pressure) or the downpipe that will have water running through it whenever the flat upstairs uses water and/or when it rains.

PLEASE HELP!! i don't want to instruct a contractor to fix one thing if it ain't broke! based on these pics, what would you reckon is the probable cause of the damp? i've marked it's approx. location and size in black.









any thoughts / advice welcome.

 

[foxhole]

It could be a leaking pipe, it could be the external pipe or the overflow pipe in the corner [where is it fed?]it could be a poor seal on the window it could be the extension roof is not correctly installed allowing rain water down the wall.It could be a leaking/blocked gutter which overflows and runs down the outside of the pipe using the foam to suck it into the wall .Can't really say from a few pics, the foam certainly serves no purpose and should be removed.The foam may even be hiding a gap at wall joint.
Would help to drill a few exploratory holes or cut out a section of plaster, easily repaired.

 

[ree]

Why not post this on the Building forum, or the Plumbing forum?

Perhaps go to the guttering that the RWP drains, and check from there all the way down to the ground that the RWP is sound - water test from the gutter outlet.

There is an overflow pipe (copper?) peeping out near the RWP in pic 3.
Where does the o/flow pipe come from?

Is the extension two-story? Is there a bathroom above?

Where is the foam?

FWIW: your render is touching the ground level

 

[KenGMac]

diy_fun_uk, hi

One thought is that because you can see and touch the rising mains water pipe if you can touch it,then if there is a leak from it, it could be argued that at least some of the escaping water will then run back down the outside of the pipe? the pipe should be wet or damp, or dripping?

if the pipe is totally dry then this tends to eliminate the rising pipe as a suspected source.

A further thing that you can do with this rising pipe is to use a screwdriver or similar, place the blade of the driver against the pipe and put your ear to the handle end, if there is a leak you may, stress the word may be able to hear the leak as a high pitched SSSsss?