I have a pebblecoat 4-square house built in 1916. It has the original slate roof with a
small flat area in the center (about 5’ square) where the chimney came through. When we
bought the house 7 years ago, the flat area of the roof had been leaking down along the
chimney for at least 10 years. We removed the chimney from the roof, attic, 1st & 2nd
floors. It is still in the basement. We had professional roofers install a rubber membrane
roof on the flat area, including new flashing, and have had no leakage. We patched the
walls where the chimney was with wallboard and taped & mudded it up to the original
plaster walls. Now whenever there is heavy rain or high humidity, the plaster wall along
both sides of where the chimney used to be oozes or sweats. It almost feels slightly oily
to the touch. The new wallboard that covers the void where the chimney was remains
clean and dry. It mostly dries back up until the next wet day. We have laid paper down
on the attic floor and are positive that the new roof is not leaking. There are no plumbing
lines or ductwork anywhere near this area. Can anyone tell me what is causing this? I
can email a photo if it would help.

post a photo, Is the wall where the chimney used to be exterior or interior?

It's an interior wall. I don't see where I can post a photo.

OK, If the wall is oozing some substance, Its an iterior wall, and the new rock placed where the hole once was. The only thing I can think of is.
Is there some sort of spray foam insulation behind the older walls?
Is the stuff appearing only when it rains outside or high humidity? Or is it appearing anytime.
Has it gotten worse, stayed the same, or stopped all together?
Something is leaking somewhere. Chemical reactions can cause this to occur, but it will happen all the time or until the chemical reaction stops.
What kind of wall is it. Old plaster with new sheetrock along side? What is behind it. First floor, Second floor?

This wall is on the 1st floor, but the upstairs is having the same problem. It just doesn't show as much up there because we haven't finished rehabbing the upstairs yet. It is 90 year old plaster, very hard and dense, harder than I have ever seen, over wood lathe & fir studs. The plaster is in excellent condition for its age throughout the house with very minimal cracking except in this area where the roof leaked along the chimney. The long-term leakage there made the plaster covering the chimney very crumbly. The crumbly part was removed with the bricks.

No insulation. We used the open cavity to run new wiring up to the attic and second floor when we tore out the chimney, but other than that it is an empty wall cavity. Then we patched the attic floor with plywood. No insulation in attic either because of the wood floor up there instead of open joists. We would have to tear up the entire tongue and groove floor to insulate the attic.

There is not much paint build-up on the wall itself because it was covered with several layers of wallpaper from when it was built until we took all the layers off and primed & painted 7 years ago.

It only happens during rain or high humidity weather. It doesn't even need to be hot. 2 weeks ago it was 65 degrees (in January!) and rained for 2 days and it did it then. It is getting better over the years. Maybe in 5 or 6 more years it will stop on its own. I have posted a link to a photo in photo bucket. Thank you for taking the time to try to figure this out.

Joan

http://s258.photobucket.com/albums/hh250/joaniebu/?acti...nt=walloozing008.jpg

Looks like you still have a chimney, but instead of bricks, it's made of drywall and plaster. My guess is that cool air is travelling up the cavity where your chimney stood. When the plaster gets cold enough, near the attic, the moisture condenses on the wall surface. Get some insulation above it to keep it warmed above the dew point and it will quit. block off the bottom of the shaft to slow the air travel.

Totaly agree wiht Maintenance 6. Moisture may be coming up from the basement as the current chase is acting like a chimney.
What the stains remind me of is nicotine stains. The yellowing often bleeds through paint unless its properly cleaned and sealed before the paint goes on. This stuff can often feel sticky. Any dampness that comes up from the basement can be enough to make this stuff bleed through the finish. Try to paint with a oil base sealer primer and then repaint. That may help. But closing off the chase is a good idea as well. Not only to stop this from occuring but to prevent heat loss and a quick moving fire if it ever happens.
FYI love the natural trim. Must be a lovely home. Not to many folks leave it like that anymore.

Thanks guys. We will definitely try your suggestions. My husband actually had the same theory, but couldn't figure out why cool air would move UP a chase.

To answer that question is simple, sort of.
Even though the air appears to be cooler then that of the house, Its not cooler then the air within the attic during some times of the day or evening.
So a natural chimney effect takes place and air rises into the attic.
Also during warmer months, The natural ventilation within the attic pulls or draws air into it as it vents out. If the attic does not have enough natural makeup air, i.e. soffit vents it gets it where ever it can. The old chimney chase. Even if you do not correct this issue with the stains, You will save a ton of hard earned money on savings from energy use by sealing the chase off.

Everyone is wrong,The real cause of the problem is due to efflorescence thru the plaster,the previous leak caused soluble salts to be deposited at the surface and now they are attracting ambient moisture from the air thats why it occurs when it is damp outside.You need to scrape old plaster off completley and treat with a sodium silicate product such as ashford ,etc. Thanks T.J Bentley Rembrandt Surface Systems,Inc. Sarasota Fl.

Hi Joanie, First, with respect to the other posters, one has to see, feel, smell and personally inspect the surface as well as the home to make a complete and accurate diagnosis of the problem. It is most likely a combo of several issues. Our suggestion is to contact several Fire and water restoration companies in your area and have them do an inspection. Also, call you homeowner's insurance adjustor. They have expertise in moisture problems and will tell you if you're covered. Even if you are not, they can give you a referral to a reputable contractor who can fix your problem. In closing, you can also contact your local BBB for one. Make sure you get a signed estimate and contract as well as a clear understanding of their guarantee. Sometimes remodeling can bring out the worst in a house. It's important to get professional advice before making any structural changes. Best to you and yours, Dan

Thank you TJ and Dan for taking the time to figure this out. TJ, your theory would explain why it happens to just the real plaster on each side of the old chimney and not to the new drywall covering the void. This plaster is rock-hard. We removed the crumbly stuff with the chimney. Do you think we could get away with just removing the paint and scrubbing down the plaster before we seal it with the sodium silicate product? I see that the product is for industrial concrete floors. Do you know if it is available for homeowners? We are not well off and very rarely hire contractors. (Also we enjoy the satisfaction of doing things ourselves.)
Joan

Dear joanieb,
You mentioned that there was wallpaper on the old plaster before painting. There could wallpaper glue remaining
under the paint you put on. Try sealing with an BIN or oil based primer. Wallpaper glue can ooze throgh water based primers and paints. Moisture in the air can make it much more visable, even sticky or liquid
Good-luck
evg

You may want to try digging-out as much plaster as possible and then skim-coating it with fresh plaster, followed by B-I-N seal primer. This has alcohol in it, so watch the flammability issues in the Wintertime, but it will usually "kill" anything. We used to use it for fire restoration painting when I worked for a fire damage restoration company.