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I bought a house last April. Now that it’s cold again (live in N MN) moisture and mold is forming at the ceiling wall joint on the N. side of the house. The mold is forming right at the point of the ceiling joist where is sits on the north wall. You can see where each of the joists is and where all the nails were driven through the drywall. The attic right above has gable vents at each end and is heavily insulated above the joints with batt insulation. I did find a plastic vapor barrier between the drywall and the batts. There are vents in the outside soffits however I haven’t been able to find out much about them yet. There is also mold forming at the base of the west and north wall in the corner. Any ideas why this is forming and how to stop it. My wife is having trouble breathing with the mold. I can attach a picture if needed to help explain the problem.
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"You can see where each of the joists is and where all the nails were driven through the drywall."
You practically answered your own question. Heat conducts through the joists more than through the insulation. Houses in Fairbanks need to repainted every few years because water and grease condense on the joists. Then dust sticks on that. Pretty soon you have off-white walls with brown stripes every 24 inches.
But since you only see it in a few places, I'm thinking those particular areas have either less insulation or more air leakage. An energy audit or a home inspector with a infrared thermometer should help pinpoint the underlaying defect.
Reducing your indoor humidity will help. Reduce it enough and you will eliminate all the mold. But you'll get chapped lips, dry skin, and static sparks much more. Run the fans during all showers and cooking helps. Cracking a window gets outside, cold dry air into the house. Or you can purchase and operate a duhumidifer. Any of these are cheaper, initially, than ripping into the wall. But fixing the problem saves energy, allergies, and the building envelope into the future.
*Thank you for your input. Could a secondary 2X4 inner wall help control the heat conduction through the frame ans top the mold. The drywall in the corner especially is getting a little soft where this was obviously a problem before we moved there. If the present drywall was completely covered with another stud wall, would that keep the health hazards from the mold from coming through to the interior? I realize that something would probably have to be done with the ceiling too, but I can deal with that.You mentioned moisture in the house too. Last season we had a wood stove which we supplemented the electric baseboard heat. The wood stove obviously dried the air. This year the wood stove is gone and we have added two non vented propane fireplaces, one in the basement and one on the main floor. Do the propane fireplaces help add to the humidity in the house too?
*A non-vented fireplace adds humidity big time. Especially if you use them for heating, not just for looks a few evenings a year. Some are only recommended for occassional use, not for normal space heating REGARDLESS of what the salesperson said. Read the factory literature.At an absolute minimum, get a Carbon Monoxide detector. Bob Walker and I have posted numerous thoughts on them over the years. Seach on each name plus "carbon monoxide detector" to find those threads.Another insulated stud wall, especially with offset studs would almost certainly eliminate the mold. But questions remain about the underlaying cause and how much damage has been done (no building materials should remain wet for long). -David
*Jerry,Is one of your gas heaters isolated in a room? Tryclosing the dorr and testing the humidity in the room before and after. Crank up the wood stove if you have to.
*Are you sure it's mold? Try dabbing it with Clorox. They say Clorox will remove/kill mold but not soot, which also forms such patterns.Do you burn a lot of candles? Unvented heater? Both can cause soot. Are there soot deposits around the registers (assuming GFA here.)If it is mold, you need to control the condensation by (i) reducing humidty levels or (ii) warming up the cold spots. (or, of course, both.)Even if it is mold, David's advice to get a CO detector is spot on in any house which has a combustion appliance (including a self-cleaning electric oven!) I recommend the one's with an LED digital readout. They tell you more and sooner. The one's that only sound an alarm are designed to try to wake you up enough to call an ambulance (exageration there, unless you are among those who are sensitive to CO.)
*In answer to some of the questions posed above. The free standing propane fireplace is in our living room which precludes closing off the room, and we have been using it exclusively this season to cut down on utility bills for the baseboard heat. The wood stove has been removed as a condition of the sale of the house. The former owner removed it. The discoloration on the walls is definitely mold and I have been cleaning it regularly with clorox, but an now cutting through the paint because of so many cleanings. I wondered about the propane heaters hadding moisture since we have the heat shrink plastic on the windows as an added barrier to condensation and there is almost always heavy moisture on the plastic.All your answers have been very helpful. It looks as though maybe we will go back to the electric baseboard heat and add another stud wall to the existing one to add insulation and remove the heat transfer from the framing members. Thanks to everyone that has contributed to my problem. It is much appreciated.
*The propane is definitely adding moisture, without a doubt.Some of your wifes symptoms could be Carbon monoxide poisoning.My instinct is that you have voids or shorted batts poorley placed at the locations you are seeing problems. Loose cellulose or spray foam might get you a better job. The mold is only the symptom, not the cause. The cause is a bad insulation job. Rectify that and you'lll stop the condensation that feeds the mold.
*Heavy moisture on the plastic indicates way too much interior moisture. Those propane units are probably a major culprit. How old is the house? What's the cellar like?Steve
*The house was built in the late 60s. The basement is a walk out. The three walls within the ground are full block walls and the north wall which is the walk out side is half block and half wood framed. We get condensation on the block walls that are above ground level which has caused some mold in the past. I plan on putting some insulation on those walls in the form of ridgid foam. We already foamed and closed in half of the basement for a bedroom/living room area and they seem to stay much warmer and drier. However we still do have some condensation forming small puddles which comes out from under the foam and puddles on the concrete floor. I used 1" foam directly glued to the block and then a 2X4 wood frame with fiberglass batts in that part of the wall. We don't seem to have a moisture problem to speak of in that part of the basement where we have our second propane fireplace.
*How's this for a theory -Lack of perimeter heating (baseboard turned off) and dependence on interior / radiant source (propane FP) allows exterior walls to chill below dew point, even on the interior face of drywall. Thus ANY moisture coming in contact with very cold wall condenses. Jeff
*Every pound of propane you burn generates 1.63 pounds of water vapor. A 500-gallon propane tank holds 2,200 pounds of propane and represents 3,600 pounds of water generated inside your house.Get a direct-vent heater (takes outside air for combustion and, more importantly, exhaust ouside like a proper combustion device). Monitor is one brand Toyo is another. It will let you heat for a lower cost than electric baseboards AND be safe.I agree with Piffin that you should consider if your wife's symptoms may by low-level CO posioning. BobW has posted signs and symptoms in the past.The condensation may be forming high on the wall because the most humid air (exhaust from the unvented propane fireplace is also the warmest and will rise to the highest spots in each room.Unvented fireplace salespeople should not be shot (although that isn't a bad idea). They should be placed in a small room with one of their products operating. -David
*If you are having enough moisture in the basement to form puddles at the base of walls that are already foamed, presuming that it is well done without voids, leads me to suspect that the block walls are leaking water from the soil. Does it show up in heavy rains in summer when heat is off too?I don't know what to do about the salesmen - after all, they're selling hot air.Jeff, I think there is a lot to your theory.
*to help your significant other out until you solve the moisture problem (probably the propane heating):wait for the clorox to dry, rinse with water. let dry. follow up with ammonia. the bleach kills the living stuff. the ammonia will kill the spores. brian
*The puddles form as a result of water condensing on the concrete block and running onto the floor. The north wall has no soil against it--totally above ground. When I put the foam to the wall I glued it with construction grade subfloor adhesive. Worked great to hold the foam directly to the block. I then built the 2X4 inner wall over the foam so the block never comes in contact with the 2X4s. The cavities in the 2x4 wall are then filled with R11 fiberglass batts. I would have thought that would have been enough to keep the block insulated from the inner temperatures. However, there must still be enough temperature difference between inside and outside to cause the condensation. It then finds it's way to the floor behind the foam. I'm lucky not to have a seepage problem. In the summer during the hottest days the concrete floor sweats if I don't keep a fan turning.
*I am going to try your idea of the ammonia. I've washed the molded area with bleach a couple times so far and I'm sure I'll have to again, but it keeps coming back. Maybe the ammonia will keep that from happening. You can only wash drywall so many times before it starts disintigrating the wallboard which appears to be happening in some places.
*Sounds like you have a very wet house. Try a way of reading the huimiodity. 19% is plenty for wood. 40% is comfortable for people. I'm betting you have over 60%
*"Unvented fireplace salespeople should not be shot (although that isn't a bad idea). They should be placed in a small room with one of their products operating."The trouble with that is they don't mind it. Whenever I see one during "heating season" I walk in with my Monoxor II, stroll around and get all sorts of high readings. I'll call a sales person over and show 'em what the readings are. They don't care! (Readings are often above BPI evacuation standards.)We need to come up with something they'll feel!
*b High levels of CO can kill; be aware that regular exposure to low levels of CO can cause long term serious health problems. Just because you aren't dead doesn't mean you don't have a CO problem!Have your home (and propane heater) checked for CO - I recommend someone who is a Building Performance Institute Carbon Monoxide Analyst.If there is evidence of CO poisoning, pursue medical treatment (It can be hard to find a doc who will know about treatment other than emergency treatment, but there are treatments available.)b Also, be aware that there is growing concern about the health efects of mold in homes. There are numerous, conflicting opinions about mold and its effects, but it sounds like your house is a candidate for significant mold issues.
*bob's right. it's interesting. i returned to property management recently and discovered what a concern that the health risks pertaining to molds. it was a practical problem for myself... recaulked tubs (stripping it all out and replacing with new latex caulking) and 6 mo - 1 year later it was filled with mold again. found this ammonia answer in a reader's digest article. hasn't let me down.one other thing to help out your significant other in the future. when you repaint, paint with oil-based paint (if it's an area normally painted with flat wallpaint, chose the eggshell finish - you'll like it). the mold is actually feeding on the water-based paint (and drywall paper, if you have rocked walls).brian
*follow up...no need to add a second wall. the oil-based primer and paint will be adequate to seal the original surface. i doubt that you will observe the moisture problem now that you've stopped using the propane heater. if by chance you do, a dehumidifier with humidistat would be in order. best prices found on eBay.brianBA degree, UCLA (Microbiology)
*For a long term fix you need to do more than just kill the mold and change out the stoves.You said the drywall is soft. For a long term fix cut it out. Look at the underlying framing and insulation. Bet you find it soaked and maybe even rotten. Take it out and rebuild the area with proper framing and insulation. Sure this takes a bit more time and money. But it how much is your health and comfort worth?While you are at it take a look at other places in the house. If you are having problems in one spot you probably are in others too.If changing out the stoves doesn't solve the moisture problem then you'll need to add ventilation. An energy inspection can tell you which is best; a heat exchanger or just an exhaust fan. But, if the wood stove was doing the job before and your only change is to move to the unvented heaters getting rid of them and fixing the damage will most likely take care of things.
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I bought a house last April. Now that it's cold again (live in N MN) moisture and mold is forming at the ceiling wall joint on the N. side of the house. The mold is forming right at the point of the ceiling joist where is sits on the north wall. You can see where each of the joists is and where all the nails were driven through the drywall. The attic right above has gable vents at each end and is heavily insulated above the joints with batt insulation. I did find a plastic vapor barrier between the drywall and the batts. There are vents in the outside soffits however I haven't been able to find out much about them yet. There is also mold forming at the base of the west and north wall in the corner. Any ideas why this is forming and how to stop it. My wife is having trouble breathing with the mold. I can attach a picture if needed to help explain the problem.