Walls and Ceilings - white powder on the bedroom wall

I have some white powder appearing on 2 sides of the bedroom wall. This is only seen in one room. It almost looks like some white brush strokes. we have cleaned it once and its come back again.
The walls are painted dark blue. Is this mildew !!!
thanks

Welcome to the forums!

Are they the exterior walls? How old is the house?

Look higher up on the ceiling and look for small pin holes. Is something chewing it's way through? Mildew would be darker and not a dry powder.

It is effervescence. You are getting moisture from some where

We too have this on 3 of our bedroom walls. 2 walls are exterior 1 is not. I see that it is said that it is efflorescence which I am not ruling out but the research I did on the subject only talks about that happening with stone/masonry. Our walls have fiberboard exterior and drywall interior.

If anyone has any more insight on this I would greatly appreciate it.

Welcome to the forums n8_dog41280!

As far as I know efflorescence only happens with masonary products. Have you tried washing the substance off of your walls? does that remove it? does it return? how soon?


I know you ask 1 question and get more in return :D but maybe with enough info, we can figure it out ;)

Pretty sure it's a moisture problem somewhere.
What is the exterior wall cladding?
Is there a tub or shower on the other side?
What kind of floor construction? Slab on grade? Basement? Crawlspace?
How high up the wall?
If not a tub or shower what else is on the other side of the wall?

What part of the country are you in?

Could there be plumbing inside the walls?

I have seem drywall joint compound bubble and fizz from moisture on the other side.

Plaster, too will effloresce from moisture inside the wall.

Let us know.

Did you ever find out what was going on? I am having the same problem in one of my bedrooms (which ironically is also blue). I have washed with bleach, antibacterial disinfectant, etc. but it always comes back after a few days. I have thought about moisture but one of the walls is a shared wall with another room and there is no issue on the other side.

I would love to know if you found any answers

Water from whatever source will find its way down a masonry wall and find its way out eventually. Now if you don't have a masonry wall I cant think what else it might be. I've seen this happen when lightweight plaster is used to patch sanded plaster.