I live in a multi-unit building in Jersey City, NJ and I decided to take the sheetrock off the exterior walls to expose the brick, a very popular thing in older city dwellings here around New York City. After completing the demo I noticed that some of the bricks looked like they were painted white with some type of overspray. I thought it gave the wall character until I noticed that the white was actually some type of mold or fungus. It has a powdery consistency so I decided to brush it off with a scrub brush and a little muratic acid solution. Some of it has gone away and some seems to be coming back. Does anyone have any idea what this is and what I need to do to eradicate it? Thanks for any helpful suggestions.
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I am not a mold specialist, but what you describe sounds like efflorescence of the brick. Is this white powder a bit thick, sort of crystal like? If it is efflorescence, is there any moisture source migrating into that brick? You usually find this stuff in a basement wall, down near the floor.
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I'm with Calvin, sounds like efflorescence, which apears when mositure moves through masonry and picks up some salts from the masonry. When it reaches the inside, it evaporates and leaves the white powder salts behind.
However, there are whitish molds. This might be one of the few cases where a mold test might be appropriate. (Note that the experts are generally coming to agree that mold testing is unnecessary in most cases.)
One possible test: put some cholorox on a small section and see if it goes away. Cholorox is supposed to clean mold, but not effloresence, but I can't vouch for that, though. Effloroesence has a salty taste, but I don't recommend the taste test!
Thanks to both you and Calvin for the replies. I think your suspicions are most likely correct about the efflorescence. On closer inspection it only looks like mold when it starts to reappear. If it goes undisturbed for a while it does get thick and starts to flake off, which doesn't sound like the behavior of mold. I will do the clorox test, but I figure the muratic acid test is already giving me the same results I will get from the clorox.
I was considering putting a few coats of clear polyurethane on the brick to give it a glazed look but now I don't know if that is going to be such a good idea. Is there anyway to stop this from continuing? The bricks never sweat per se. The wall is actually the interior layer of an exterior wall. I am guessing the interior wall is actually a veneer of brick since the entire wall from outside to inside is almost a foot thick. (I am not familiar with the construction techniques of these buildings, probably 1950's). The exterior side has a skim coat of mortar like dryvit and it is painted. A new roof was put on the building about two years ago and the walls are capped with aluminum flashing up there (4 floors above me). This wall was covered with framing and sheetrock for years so I don't imagine the problem is extreme but . . .
Thanks for your help.
I was considering putting a few coats of clear polyurethane on the brick to give it a glazed look but now I don't know if that is going to be such a good idea.
Nope, probably not a good idea; it would just seal moisture into the brick (but not for very long.)
Is there anyway to stop this from continuing? The bricks never sweat per se. The wall is actually the interior layer of an exterior wall. I am guessing the interior wall is actually a veneer of brick since the entire wall from outside to inside is almost a foot thick.
You need to keep moisture from getting into the walls. Impossible to say where it's coming from, from where I'm sitting. It could be a bad roofing job, it could be the exterior needs to be sealed with a masonry sealer. "Sweating" or lack thereof isn't necessarily significant, Sweating is usually a form on condensation, which is unlikely on brick walls above grade.
(I am not familiar with the construction techniques of these buildings, probably 1950's).
I'd guess earleir, but don't know much about that area other than growing up 20 miles from there in the 50's. Full masonry walls tend to be from an earlier time.
The exterior side has a skim coat of mortar like dryvit and it is painted.
Ahh. Dryvit, (aka synthetic stucco) was developed in Europe after WWII to come up with a way to insulate old masonry buildings. It has had lots of problems in the States being used on frame construction because of improper application and (some claim) faulty material and application design. The problems have been water infiltration which then gets into frame walls and is sealed in by the rest of the synthetic stucco and then causes problems, sometimes big problems.
A new roof was put on the building about two years ago and the walls are capped with aluminum flashing up there (4 floors above me).
Another possible source of water infiltration.
This wall was covered with framing and sheetrock for years so I don't imagine the problem is extreme but . . .
Was there mold on the backside of the drywall you removed? That can be significant. The conditions you describe offer a high potential for mold growth. Mold needs oxygen, temps between 40-100 degrees (usually) food (including the paper liner on drywall) and moisture.
Also, mositure in brick can be a big problem.
You might want to consider asking neighbors if they have had symptoms of mold exposure. The possibility of a mold problem is likely to get the owner's attention in this day and age; and the owners insurance might cover repairs if they still have an older policy in place. (Insurance co's are currently stripping out mold damage from their policies. Don't wait if you want to pursue this potential issue.)
I think you guys are almost 100% right that it isn't mold. I was attracted to look at this thread because the title seemed wrong. Mold needs food to host it and brick ain't it. Your desription had me thinking efflourescense before I was done reading it.
So where is the moisture coming from to cause it? Maybe the shell (roofing and stucco) is a tight seal and no exterior water is coming in (not likely). Then the source of the moisture would be what is produced inside the building and gets trapped in the brick wall. It could be condensing in cavities of the masonry and then leading itself back in, picking up mineral on the way. In this case, sealing the brick would help but it could be coming from upstairs neighbors area so you can't get to it and do anything. The only way to be sure, IMHO is to be sure you are sealing the whole wall, top to bottom, inside and out. This is apparantly not doable.
I would consider painting on a slurry of Thoroseal white for the effect you are looking for. It'll give you a sealer and a whitewash look and it combines with the masonry to bond and is less likely to flake off but will still breathe a little. Use their admixture. After it cures, you could paint it again with a latex formulated for masonry applications.
Then, if it still efflouresces, you can call it charachter marks...
Excellence is its own reward!
Edited 8/4/2002 2:00:11 PM ET by piffin
Mold needs food to host it and brick ain't it.
I've been trying to remember if I've ever seen mold growing on brick. I think I probably have, but couldn't swear it.
I have seen it growing on concrete block, however. The block obviously isn't a fiood source, but the years of dirt that have built up (on basement walls, for example) can be. I'm thinking the same situation could arise with brick, but maybe brick has some natural mildewcide?
Maybe. I did say almost 100%.
And I was thinking you would be here on this one Bob. Where's the water coming from in your thoughts and would the Thoro hurt anything?
I was figureing that the high alkalii in the masonry is what prevents molds. I have seen minor mold on block or concrete walls below ground where a pile of crap is left against it to hold amp for years, but the stuff piled was the food host.Excellence is its own reward!
I was figureing that the high alkalii in the masonry is what prevents molds.
THWACK!!! Self-inflicted dummy slap at this end. Of course! When I've seen mold on block, it's been on painted block basement walls. Honorary senior moment on my part!
And I was thinking you would be here on this one Bob. Where's the water coming from in your thoughts and would the Thoro hurt anything?
I'm not sure. I'd be concerned that it might seal moisture in and let it build to high enough levels to cause some damage, but maybe it would just force the dampness to the outer walls and .... Hmmm. Jersey City (or Joisey City, as we native Joisyites put it!). Gets cold there. Could result in spalling on the exterior of the walls.
WHere its coming from is anyone's guess: could have been stupid mistake in the roofing job or dryvit job. Those seem the most likely.
Could be internal sources getting into the wall higher up. Lots of possibilities.
If this is a rental or condo, I'd raise the mold red flag, That should get management's attention!
Mangement should definitely know about it! This is a condition that can affect everyone in the building. But he did say that it's a very minor one.Excellence is its own reward!
Firstly, let me say thanks to you guys. This thread has been very educational for me.
I didn't see any mold on the sheet rock when we took it off. The unit is actually a duplex unit using the 1st and 2nd floor. The brick was exposed on both levels. There is hardly any of the efflorescence on the 2nd floor. The 1st level is about 200 sq. ft of exposed brick and about a third of the wall is affected. Beneath that level is the basement where the brick wall is painted white. I haven't noticed any mold or efflorescence and very little moisture unless there is a flash flood type of rain.
I will have to consider the suggestion to apply Thoroseal. I'm not sure it will be any better than reframing and putting sheetrock back up. I guess the first thing to do is to confirm it definitely isn't mold (feel pretty sure from what you have given me that it isn't but ...) and that it is not symptomatic of anything more harmful.
Thanks again for your help. Any further comments are definitely appreciated.
There is hardly any of the efflorescence on the 2nd floor. The 1st level is about 200 sq. ft of exposed brick and about a third of the wall is affected.
That suggests that there is a leak in the exterior cladding. Dollasr to donuts there's a window above the area with efflorescence. Dryvit is possibly one of the most commonly screwed up building materials, especially the detailing around the windows.
QUoTE
I was figureing that the high alkalii in the masonry is what prevents molds.
THWACK!!! Self-inflicted dummy slap at this end. Of course! When I've seen mold on block, it's been on painted block basement walls. Honorary senior moment on my part!
ENDQUOTE
We were getting so smart, I had to run across this moss on brick yesterday!
Another try at attaching the pic: