White powder behind paint

[Jason2011]

I am re painting a spare room and around the window there is a lot of paint which is cracking. I was scrapping the paint away along with other old coats I came across this white powder. It easyliy turns to dust if scrapped.

I was just wondering what this is and how to fix it?

The rest of the room there is none.

Thanks for any help.

Here a pic of it View media item 74300

 

[footprints]

Sounds like a case of Distemper, not the sort dogs get though!
Have a look at this thread that is current.



//www.diynot.com/forums/plastering-rendering/whats-this-on-my-wall.395826/#3048373

 

[JohnD]

how old is the house?

is that a conservatory roof above it?

were there any marks of damp?

 

[Jason2011]

It's 1952 build. It's in an upstairs bedroom. And it did have some small bits of damp/mould

 

[JohnD]

is your photo upright? what's that at the top?

 

[Jason2011]

Here is one shows position better View media item 74304

 

[JohnD]

so the photo is not upright.

is the left hand side the top?

what is above it?

does the gutter or roof leak?

or is it condensation? how is the room ventilated?

 

[Jason2011]

Yeh left is top stupid I pad.

Above it is the main roof guttering but we do suffer a lot with condensation on the windows. And before this used to be the room where're washing would dry in winter months with a de humidifier.

No leaks that I am aware of

Ventilation is only through opening window or leaving it on the latch so slightly open

 

[JohnD]

then the powdery material might have been efflorescence resulting from the damp wall.

you can clean it off with a broad metal scraper. Dry the wall out well before redecorating. If your windows have no trickle vents use the ventilation position. Fresh air dries out walls, not heat. Don't wet the powder, which is mineral salts, or they will soak back into the wall.

 

[Jason2011]

Ok makes sense as the damp was only around the window. Will have a go at that thanks for your help

 

[JohnD]

inspect the roof and gutter during rain, there may be water dripping or splashing on the wall.

if this is the only external wall of the room, it will be the one that suffers condensation, because it will be cold.

 

[Jason2011]

Yes it is the only wall that's external so once scrapped it dry it paint it. And just make sure that we keep the condensation down by leaving the window a jar and we also have a dehumidifier for the washing. And I am hoping that should keep it away.