Is my builder fobbing me off? Damp patch...

[Grouseman]

We are coming to the end of an extension and complete refurb of our property.
All internal walls were plastered in December, left to dry then professionally decorated (mist coat etc)
Since April, a patch of paint above the skirting has been slowly flaking off. The exposed plaster left behind looks damp (dark pink, rather than the light colour of dry plaster.)
The wall behind is new blockwork, built as part of the works.
We have not encountered any similar issues throughout the rest of the house.
I have spoken to my builder about the problem and he said it is 'salts' coming through as it is an old wall but it is a new wall he assembled as part of the build!!! I'm therefore concerned he's trying to fob me off and that it may be something more serious. Note: I will need to make final payment to builder in the next couple of weeks...
As a lay person, I'm worried it may be a leak from the towel rail pipe that goes into the wall, through the skirting.
Does anyone have any ideas what might be causing the damp patch and whether I should be concerned. Also any advice on how to play it with the builder would be appreciated!
Thanks in advance!

 

[JohnD]

radiator + pipes +water + damp = leak, perhaps.

How's the pressure on your boiler?

 

[vinn]

Why not search the recent threads on exactly what you ask about?

As above, there could be a leak on the radiator flow and return - but where do they run from and to.
Are they above the floor or below it?
Whats on the other side of the wall?
Its not reassuring to see pipe stubs coming out of a skirting - they should have come out above the skirting.

Assuming that this is the new extension floor, did you notice a membrane (DPM) going down below the concrete?
Does the new block wall have a DPC?

 

[wessex101]

It would be reasonable to withhold a small amount from the final payment, say £300 to £500 until the problem is rectified (assuming that there aren't any other snagging items).

I assume that you have not got a defects period, 3 to 6 months.

 

[mointainwalker]

If your builder is saying it is "salts coming through " then he is admitting that he hasn't plastered the wall with a salt-resistant plaster and you should be pulling him up on that to start with, but not ignoring the possiblilty of high outside ground-levels etc that may also be adding to the problem.

 

[Grouseman]

Hi All. Thanks for the responses - much appreciated.

JohnD - I've just checked the boiler (system boiler with megaflo) and the dial is in the red, at around 0.3 bar. So would this suggest a leak? Am I right in thinking it should be no lower than 1.5 bar?
vinn - From memory the pipes that feed the towel rail disappear below a concrete screed. The other side of the wall is our kitchen but there are appliances that use water up against that wall. I seem to remember there was a DPM but not sure about the DPC - it's an internal wall, so would this make a difference? The wall was build using a couple of courses of red bricks then grey blocks above...sorry for my lack of know how!
wessex101 - good advice about the final payment, we don't have a defects period I'm afraid.

So on balance, do you think more likely to be a leak rather than 'salts'???

 

[WabbitPoo]

yes

 

[rochester plasterer]

How long ago was that plastered ?

 

[Grouseman]

Hi rochester plasterer. It was done in December. Not had any similar issues anywhere else in the house and it was all done

 

[kazuya]

have you topped the boiler back up into the green?
they do need topping up now and again but not often, and yours is very low
it does all look suspiciously like a leak

 

[rochester plasterer]

That's strange, like you say it is clearly not dried out plaster under the paint, looks like it possibly hasn't been 'mist coated' to be fair could be wrong. There is definitely a damp issue there that multi finish looks like it was plastered a couple hours ago

 

[Grouseman]

It is strange that it's just an inch thick strip just above the skirting...

 

[rochester plasterer]

Yea like the others have said if there's a small leak going on behind there it will slowly start soaking up the plasterboard, so over time this will get worse. You can see the multi has soaked up this leak as it is really wet. Its going to be a bit of a mission but that rad needs coming off and the skirting to find out what's the problem in that wall, as vinn says the pipes should have come in/out the wall just above the skirting. That's no salt problem.

 

[rochester plasterer]

It's a bit hard to see in the picture but can you see any staining around the paint work near the bare plaster

 

[Grouseman]

A couple of close ups - can't see any staining, just a little bit of chalkiness (just off centre in top photo)