Redecorated Bedroom - odd white furry mould near window spreading + more damp?

[uptoyou]

Hi all,

Having spent a lot of time and effort redecorating daughters bedroom and fixing (at least I thought I had), a damp issue, are things now getting worse?

Highlighted area where damp, black mould and peeling paint used to be before decorating:

Weird furry mould (?) where there was never any damp previously. Looks like it has burst through the plaster. I scraped it out a few days ago and its kind of bursting out again!

It was spreading a bit but it looks like it has at least stopped to the areas you can see:

When I was decorating I pulled all the old sealant out from around the window frame and there were big gaps to the outside, a breeze coming through and some daylight - so I used expanding foam down all the sides and along the top to seal it, cut it back and then finished with sealant. You can see how the sealant is turning a 'plaster' colour and you can just about make out a change in colour along the top (circled) - this is almost now dripping with water - I'm hoping this is just from an inside/outside temperature change but I'm concerned I've sealed something which is stopping water running away from somewhere and its settling on top of the window and soaking through...I don't know - have I sealed a vital air cavity which keeps the temperature regulated?
I have another thread here where I used Zinsser anti-mold paint on all of the inside window section but it was a disaster and kept peeling - the coverage ended up a bit hit and miss and it didn't ever really fully take - is this damp patch circled where the Zinsser is preventing condensation from penetrating the paintwork?

Any advice appreciated, thanks.

 

[robinbanks]

The "mould" appears to be efflorescence, where damp egressing from cementitious surfaces brings with it salts that crystallise as the damp evaporates away. It should stop happening when the source of the damp is removed, or there are no more salts left. Are you sure that your reparations didn't introduce a problem whereby water getting into the cavity above the window was formerly getting out somewhere in the outer skin of the wall, but is now making its way across to the inner skin? What is above this window? Is it known to be free from leaks/are there weep holes that are definitely clear of debris and sealants?

Also (though I doubt it's causing a problem this high up) note that windows frames are expected to get water in, and this they are designed to let it out again. Be careful that building works don't block up drain holes in a window opener or frame. Water may enter a frame at any joint, and is expected to collect in the lowest part of the frame and be drained away either via weep holes in the visible surface (face drained) of the lowest frame member or via holes underneath it (base drained). Base drains may drain into a sill which then has holes drilled in the front under the projecting lip and the water discharges from there

 

[uptoyou]

Thanks for the reply
I vented the windows and by the evening the top part had dried out, so it must have just been on the surface else it would still be wet.
I'll scrape out all salts/crystals and prep that area and re-finish, it;s just in a very odd place for damp to be getting to and nowhere else!

 

[noseall]

Hi all,

Having spent a lot of time and effort redecorating daughters bedroom and fixing (at least I thought I had), a damp issue, are things now getting worse?

Highlighted area where damp, black mould and peeling paint used to be before decorating:

View attachment 321360

Weird furry mould (?) where there was never any damp previously. Looks like it has burst through the plaster. I scraped it out a few days ago and its kind of bursting out again!
View attachment 321361

It was spreading a bit but it looks like it has at least stopped to the areas you can see:

View attachment 321363

View attachment 321362

When I was decorating I pulled all the old sealant out from around the window frame and there were big gaps to the outside, a breeze coming through and some daylight - so I used expanding foam down all the sides and along the top to seal it, cut it back and then finished with sealant. You can see how the sealant is turning a 'plaster' colour and you can just about make out a change in colour along the top (circled) - this is almost now dripping with water - I'm hoping this is just from an inside/outside temperature change but I'm concerned I've sealed something which is stopping water running away from somewhere and its settling on top of the window and soaking through...I don't know - have I sealed a vital air cavity which keeps the temperature regulated?
I have another thread here where I used Zinsser anti-mold paint on all of the inside window section but it was a disaster and kept peeling - the coverage ended up a bit hit and miss and it didn't ever really fully take - is this damp patch circled where the Zinsser is preventing condensation from penetrating the paintwork?

View attachment 321359

Any advice appreciated, thanks.

One looks like condensation related mould (near to the window frame) and the other looks like damp.

 

[^woody^]

Zinnser is effectively like a gloss paint that tries to prevent future condensation mould by being impermeable. It does not prevent condensation, and if the material behind it is getting damp then it won't work either.

If that "white furry mould" is powdery and crumbles, then its more likely to be salts from moisture within the plaster
drying off.

 

[uptoyou]

Thanks again for the replies.

I think it was just condensation - windows have been vented since and it hasn't returned.

I've been DIY'ing prepping walls forever and I've never had this other problem - it;s also in an odd place where there were no issues before.
The 'white furry mould' does indeed crumble, and it's still 'growing out' of the same place, albeit not as much.
There are are couple more blisters now as pictured - tapping on them feels hollow, but I will scrape it away this weekend and see what lurks behind:

 

[uptoyou]

Just to add, the part where 'mould' and bubbling is happening was never repaired or touched up, just painted!!!

 

[uptoyou]

Just posted up a new thread on this and would appreciate any thoughts from contributors to this thread if possible please > Prep and fix now, or wait?