White stuff

[ali nash]

I have this white stuff on my bedroom wall, painter put zinsser bin stain block on the wall before painting. Ignore the pattern of brickwork as it had a brick sticky panel on it, but changed our minds. You can wash it away but it's back within a week. Painter has no idea what it is. it isn't efflorescence as it doesn't appear behind a long mirror hanging on the wall. Never had a house I've lived before do this. If you know what it is and know how to stop/treat it please let me know

 

[accelerator]

Is the wall damp at all? Or is the room damp? It could possibly be a white mould. If you ran a finger across it, does it come off?

 

[ali nash]

If it was mould wouldn't it go behind the mirror? It doesn't come off unless it's washed off with water, it's so confusing

 

[accelerator]

Not necessarily. You didn't say if the wall or room is damp.

What is this brick sticky panel you mention, and did it involve adhesive, i.e. being stuck onto the wall?

 

[ali nash]

No the rooms not damp, yes the brick was a sticky panel, but it's happening above the bed where there wasn't any sticky panels

 

[aveatry]

I and going with effervescence from wet or damp and that wall is an unvented blocked up chimney brest

 

[ali nash]

Its a shared wall with a neighbour, they don't have anything on their side. We have a flat roof, but surely having a stain block painted on before the paint should have stopped it coming through?

 

[accelerator]

It is likely to be moisture within the wall that is reacting with the coatings put on the wall (effervescence), and no, the stain block wouldn't stop it.

Alternatively, it could be a reaction between the stain block and the paint.

 

[ali nash]

What would stop the efflorescence, just spent £3000 on getting my house decorated

 

[accelerator]

Making sure there is no moisture in your walls.

The fact that it's water soluble also suggests its efflorescence.

 

[ali nash]

How do I do that

 

[accelerator]

Use a moisture meter, or a thermal imaging camera, which will show temperature differences caused by moisture.

 

[aveatry]

Its a shared wall with a neighbour, they don't have anything on their side. We have a flat roof, but surely having a stain block painted on before the paint should have stopped it coming through?

Could there be a leak in the flat roof, have you asked them if they have the issue.

 

[ali nash]

It is a flat roof, next door don't have any issues, mind you it's a cream wall so seeing it might be harder. We have had problems with the roof, the drainage pipe is blocked so the overflow pipe pours when it's heavy rain. But we are having that dealt with tomorrow

 

[aveatry]

It is a flat roof, next door don't have any issues, mind you it's a cream wall so seeing it might be harder. We have had problems with the roof, the drainage pipe is blocked so the overflow pipe pours when it's heavy rain. But we are having that dealt with tomorrow

I think that may be the problem, if your joining wall has any kind of gap then it is running down the inside of your side perhaps.