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I am looking at buying a house built in the 1940’s. And one of the problems is that on the inside, mold developes on the walls when items are placed to close to the wall. Please advise….
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Dewpoint is being hit at the lower temperature behind the placed objects....Run a dehumidifier to lower dewpoint or move to drier climate????
Or possibly harvest and sell...
J
*Eric it sounds like you have a house that either doesn't have any poly behind the drywall (if it was a renovation) or the drywall is covering the old rockwool paper bagged insulation that has failed miserably.Jack is right in the sense that any objects placed in front will prevent the air (convection currents) from dispersing the moisture. The Dehumidifier will lessen the problem but not solve it.How's the siding on this house. If your siding is deteriated enough to allow excess moisture to infiltrate your house, you will have a major job on your hands. Last but not least, how damp is your basement?
*Gabe, If the moisture is from the outside to all the outside walls ...cripes it's time to demo all and start over...Rarely do I see moisture in walls from an outside source unless at a localized spot where something is definitely messed up.J
*Jack I seen it on a house one time that had had a cistern. The pipe from the roof had leaked inside the wall cavity and completely rotted out everything but the outside and inside layers. You couldn't tell from a visual inspection. When we went poking at the siding, a piece fell into my hands.Anyways, on that call we had been told that mildew was always forming on one corner also.I think though, in this case, the house was built in the 40s, it's not unusual for wood siding to be in such poor condition to leak like a sieve.Another common type of house that is a pain when it comes to mildew is one constructed of solid brick walls.
*Gabe,If you read your last post....you are learniing to agree with what I said, "the dewpoint is being reached on the inside surface of cold wall areas....And if the source of water is from the outside then usually an outside water handling component has failed in a localized region...Dehumidifier time...J
*Jack, it's not a matter of joining any side. I am not on anyone's side, I like to think for myself and my decisions are based on knowledge and experience. I use every new and innovative method, the difference is, I don't blindly use only one. Houses are too complex and varied in location, design and construction to oversimplify with one cure all. Only a simple mind would try otherwise.Now this is why we install poly under the drywall, in our new houses today, in the event that the exterior would fail to protect, it makes a perfect line of defence. Unfortunately, for every good builder, there is another who is not, and that's a fact. It's a sad commentary on our trade, that we have to try to design houses to be idiot proof, if for no other reason than to protect the consumer.In his post he indicated that the mildew was not localized. I originally refered to the basement as a possible source of excess moisture. In my second post I added the possibility of exterior siding, even brick could be the culprit. Many times in older homes the bottom of the brick weeping holes get blocked and water becomes trapped in behind. Older brick in most cases is also more porous and absorbs water, causing many moisture problems in homes and buildings.If we both did a onsite visit to the house, we would probably figure out the problem in a flash, as it is, we can only quess with the information given.
*Gabe,I never said you were joining my side...Perhaps being that you are "wrapped way too tight(in poly)"...Are you possibly having trouble seeing through the multiple layers of poly over your eyes???As an Australian ski buddy liked to say....sometimes your posts sound like you are "too full on!"Flame proof but not fool proof,One_Eyed_JackJust messin with ya to liven up this place...You actually are fun, and somewhat knowledgable... just a little thin skinned...
*Jack maybe it's because I haven't flown in a while?Time to get back into it, think I'd like to graduate to floats and spend more time fishin and huntin.
*Gabe,I almost only fly on floats...That puts the airport where it is accessable to me and to where I want to go...Livin in lake country,J
*>>Now this is why we install poly under the drywall, in our new houses today, in the event that the exterior would fail to protect, it makes a perfect line of defence.<<Gabe,I have to say this is the first time I've ever heard this rationalization for poly behind the drywall. I've always understood the rationale to be as a VDR to prevent interior moisture from migrating into walls. Seems to me the place to put a drainage screen to protect against exterior moisture would be outside the sheathing, behind the siding (ie: felt or tyvek), not behind the drywall.Am I crazy?Steve
*Steve you know as well as I do that there's a dozen reason to install poly and this is only one of the benefits.Now you're starting to get desperate and you're grabbing at straws.
*Steve,Brave poster that you are...I know you know...and you probably know that I know...And we both know what is known, yet it's still fun isn't it...Long live the poly posts...J
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eric:
all this talk about poly behind the drywall misses a key factor in your original post:the pacific northwest. I once lived in a house in Eugene that had 1-1/2" tall white fungus growing under the bed. Clover and moss would grow between the tiles in our bathroom. The problem was the site and had little to do with construction. We had the same problem with items close to the wall. No amount of dehumidification would have helped this house-we moved. Should've been tipped off by the strong smell of bleach when we looked at the place.
I'd investigate the site conditions and crawl space ventilation. But I'd be hesitant to buy a 40's era home which has endured 50 years of northwest mold, mildew, moisture and dampness. The house probably has problems which are deep and not easily repaired.
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Gabe,
Desperate? Grabbing at straws?
I'm merely voicing my understanding of the reasons for using poly, and this is one I have absolutely never heard before, and it seems counter-intuitive to me.
I'm close to giving up on your ability to stay on topic and off personal swipes.
Steve
*Gabe, are you are saying that the poly under the drywall is a final barrier in the event that the exterior waterproofing fails?That sounds silly. So, in effect, you are attmpting to stop the water so that it will only rot the frame, thus protecting the drywall?Sounds like convoluted reasoning to me!Blue
*If y'all insist on living in rain forests, y'all oughta' start building grass huts!Blue
*I hadn't read Steve's post, but you comment about grabbing straws is totally wrong. He is making a strong point, You can't claim that moisture is gravitating outward, then change to say it is gravatating inward!Make up your mind.And while your at it, explain why heat will expand something, and cold will also expand something!Totally confused, going back to beating wood,Blue
*Steve, Blue etcIf poly had only one function, you would have a leg to stand on. However it has a multitude of functions.Drywall is an air barrier. Some applications with paint also become moisture barriers. Plywood with paint and tape is also a barrier. However not every house benefits from these applications.I have openned up walls that had partial poly installed behind the drywall. The areas where we found mold and mildew were also the areas where there wasn't any poly. The same room had no mold or mildew where the poly was sound. This means that the moisture was coming from the outside. Had the poly been constant, there would not have been any mildew or mold in the apartment.I'm sure you have all kinds of theories, however I have to rely on facts.
*>>I have openned up walls that had partial poly installed behind the drywall. The areas where we found mold and mildew were also the areas where there wasn't any poly. The same room had no mold or mildew where the poly was sound.<<Gabe,Not out of biligerence, just looking for data: in these instances was there any difference in the condition of the wall cavity behind the poly vs. the non poly areas?Steve
*FredL,If you have nothing intelligent to say, say nothing.Steve,The two outside walls were identical in construction.First level apartments, first 4 feet was concrete, upper 4 feet was wood frame. Moisture was coming from the concrete to the drywall.
*Gabe,Between the concrete and the drywall seems like a useful place for it to me. I've been known to put it between below-grade stone walls and the studwall that got built up against it (kitchen in a banked stone house). I'm still inclined not to use it anymore when there is wood-frame wall on exterior side of it, though I have plenty of times in the past. Steve
*Fred,I knew there were plenty of good reasons.Just out of curiosity, have you used poly as a physical barrier to hold cells in like you showed in that picture on the other thread? Wouldn't you prefer something more permeable? Having a hard time reconciling this practice as well as use of RFIB in the same instance with the notion that it's good to leave the cavity free to dry to the inside under conditions of low interior moisture. Is it because it was in a roof situation rather than a wall and the presure is constant interior to exterior?Yours,Steve
*Steve,What about house wrap finally having a good use as a breathable hold back for DP cels on the inside warm side of a home's shell...I have been thinking about this since getting involved in breaktimepolyventism...Near the stream,J
*Gabe,I like the consistency in what I you see differently than I...Again in your own analysis of a need for poly, I think you are fully missing the problem and the solution...The concrete and it's capillary water moving ability were that walls problem...And the solution is to stop the water before it gets into the concrete or after, possibly with tu-tuf or a long term poly type product...but just having poly to protect the drywall is hiding the rest of the water damaged wall possibilities...Not good.Near the stream,J
*Jack you may be near the stream but you're off the mark.Ever stick a piece of celery in your favourite drink and watch the coloured juice make it's way "up" the stalk?The wall wasn't damaged.The moisture was in the concrete to start with and was also being absorbed from the ground under it.
*Gabe,Exactly my point and on the mark totally...The poly in the wall was, is useless where it was, is...The water has to be stopped from getting to all wood and building products that it could damage, not just the drywall.Are you saying what I'm saying, but I'm not "seeing" that?Near the stream,J
*AJ,Seems I've heard that recommended by others in the past.Fred,It's not the strength, rather the non-breathability of the poly that makes me pause. Is that not an issue in ceilings?Steve
*Gabe,I must disagree with your statement that we apply poly under sheetrock to protect it should the outside fail. Maybe I'm missing something here but I believe that the poly is supposed to prevent the moisture from inside the home from getting into wall cavities and attic spaces where it can do harm. If poly under the drywall is a last line of defense from exterior failure then youre going to have more than a couple of sheets of drywall to replace/repair. Without oversimplifing the issue the exterior envelope of the house, siding,flashing etc. should attempt to keep out all but floodwaters. While poly helps the transfer of moisture from within the house it is better to stop exterior water at the outside than try to stop it somewhere in the middle of the wall. Use bathroom exhaust and the hood over your stove to expell the largest sources of moisture and make sure your clothes dryer vents to the outside. If the moisture is from the basement then that problem needs to be addressed as well. Sorry for the ramble just wanted to clear up the poly thingy.mike
*There is more to the facts that you are presenting.Also, how come you ditched the question about cold expanding things, and heat expanding things?Blue
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I am looking at buying a house built in the 1940's. And one of the problems is that on the inside, mold developes on the walls when items are placed to close to the wall. Please advise....