Dark Circles on skimmed plasterboard

[cmacca75]

I have recently had some walls & ceilings plasterboarded and skimmed, i left them for a month, when i came back i noticed some dark circles had appeared on the plaster about the size of a football, when i painted over them with 2 mist coats and a topcoat, they still came through the paint, does anybody know what these are and how they are caused?

P.S they are all on the walls but not on the ceilings.

Thanks

 

[joe-90]

If you have a damp meter and they show up as damp then you have a problem with your outside walls. Check for guttering and stuff like that. A month is plenty long enough for whatever adhesive was used to dry.

BTW you aren't supposed to post the same question in different forums.

 

[cmacca75]

If you have a damp meter and they show up as damp then you have a problem with your outside walls. Check for guttering and stuff like that. A month is plenty long enough for whatever adhesive was used to dry.

BTW you aren't supposed to post the same question in different forums.

Sorry Joe, new to this forum business, I am just trying to find an answer for this problem.

When i knock the plaster on the dark circle it sounds more solid than the rest of the wall,

 

[joe-90]

I'm guessing that you are talking about outside walls and it is damp making its way through the adhesive. That's why dot and dab is no good for outside walls. You should have used battens (in-filled with insulation) and then boarded that out with foil backed plasterboard.

If they are internal walls then you need to check for leaks.

The main thing is to check it for moisture with a meter to see if it is a continuing damp problem or just a dried stain.

 

[joe-90]

If it's on a chimney breast then get back to us.

 

[cmacca75]

It is on all the internal walls including 2 chimney breast walls and even the wall under the staircase, I have had the whole ground floor plaster boarded and skimmed. Do you still think its a damp issue?

 

[joe-90]

No. It sounds like staining through the adhesive which has since dried. Oil undercoat and paint. (Or a stain block).

 

[peaps]

The adhesive is creating cold spots. You will find they will not go away.

 

[cmacca75]

Plaster boarded walls

• cmacca75
• 2 Oct 2011
• 1

Dark circles

These are the dark circles. Are they cold spots?, they have appeared on every wall.

 

[peaps]

Plaster boarded walls

• cmacca75
• 2 Oct 2011
• 1

Dark circles

These are the dark circles. Are they cold spots?, they have appeared on every wall.

Is it an outside wall? It looks like it still has some drying out to do so it's advisable not to paint but it's the adhesive that's causing the dark spots. If it's on an outside wall (In my experience) you will not get rid of the "shaddows" altogether and you may find it will condensate in thoses spots, due to the cold spot. If it's an inside wall I would let it dry out. a dehumidifier will help.