shadow on exterior walls.??

[foxhole]

Have been asked to do some work in a fairly modern flat, customer asked my opinion about the interior of the external walls. The screw or nails [not sure what was used] to secure plasterboard to walls show thru the decoration as dark spots, every head is visible, non of the heads are 'blown' though the finish over some is poor.
Any ideas on a remedy? should the owner go back to developer [believe they have only been in year or two]
My first instinct was to suggest a stain block over each head and re-decoration?
Another concern is that the walls in question are around the lounge and a mezzanine balcony area above meaning the walls are around 18ft high and the access is poor as the flat is on 3rd floor

 

[PrenticeBoyofDerry]

How old is the property, will it still be under guarantee?

 

[foxhole]

Not sure , probably.

 

[foxhole]

bump

 

[holmslaw]

I have exactly the same in my place.

My external walls are lined with plasterboard bonded to 40mm polystyrene. These are fixed by 5" aluminium nail/screws similar to frame fixers.

Seems that because 3" of ali nails are fixed into the cold side of the insulation this makes the nail head colder than the plasterboard surface. And warm damp air condenses on the head and leaves a stain.

The problem is made worse by fag smoke, there's not much you can do about it. And it is not a defect, its just a consequence of the method and the nails are needed for fire protection, so they must remain.

 

[foxhole]

So how does the stain penetrate the plaster, given than plasterboard screws are near black and they don't show thru.?

 

[holmslaw]

The stain is on the surface, just wipe with a damp cloth.

Before
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After
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