Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
(OP)
They look like below.
I was told that it is humidity that ascends through the wall due to capilarity
I have watched the area for around an year. We had a very dry summer in Toronto.
These spots have not changed at all. I tried to dry them up with a hair dryer
but I had no luck
I seems to be some sort of salt.
The area has roof above and gutters. The problem was originally caused by an incorrectly sloped patio that was sending the water toward the wall.
That was fixed. What could these spots be and how do I remove them?

I was told that it is humidity that ascends through the wall due to capilarity
I have watched the area for around an year. We had a very dry summer in Toronto.
These spots have not changed at all. I tried to dry them up with a hair dryer
I seems to be some sort of salt.
The area has roof above and gutters. The problem was originally caused by an incorrectly sloped patio that was sending the water toward the wall.
That was fixed. What could these spots be and how do I remove them?






RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
You can also see that the dark spots appear to follow mortar joints in the underlying masonry wall. It is likely that the masonry has a lot of moisture in the unfilled cells that bleeds through the more porous mortar joints and causes the staining. I see no weeps for the underlying masonry wall, so likely the moisture continues to collect.
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
Then I did that test with the hair drying and nothing happened
I also removed the power plugs from the wall and I tried to sniff the air from beyond the wall.
If there is moisture trapped there it should also radiate toward inside and ..no there was absolutely no smell
As indicated the problem used to be because the patio used to be sloped toward the house! That is fixed, I see no water there anymore.
Below is what it looked when the wall was receiving the water from the patio.
I would say that now I am seeing just salts which refuse to go...
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
http://www.eng-tips.com/viewthread.cfm?qid=391109
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
I would have removed the drywall, the vapor barrier and the insulation if I wanted to put that in practice
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
Larry from Lehigh White Cement Company
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
and the humidity of the wall in general. Absolutely no difference between spots and the surrounding area.
It was under 0.8% (I believe it was around 0.6%) so yes it is confirmed this is salt. I am now fixing other issues around the house while the weather still allows this and I will try to wash these spots with an light acid solution to see if it works. I am tempted to redo the parging for the entire house
I will report back when I have the results
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?
The scale says it is for construction materials, not drywall only
Yes the conductivity is what they measure that way but there is a correlation isn't it?
RE: Dark grey spots (like humidity spots) on parging.It does not seem to be water. How do I remove them?