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I was just up in my atic and saw mold growing on 3 of the 4 sides of my attic roof. I have 4 roof vents at the top of the roof and no soffit vents. I have been in this house 4 Michigan winters now and have never had this problem. Last summer i had a new roof (tear off) put on. They suggested installing soffit vents. Would soffit vents be the cure? The mold is starting to take over. Please help.
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Always curious about these things.
Do you have any new bathroom, kitchen fans or even vent stacks that are located inside this space?
Gabe
*Kari ,I,ve heard of cases where damp crawl spaces can contribute to this problem.
*mold needs oxygen, moisture, temperature and food..the moisture is comming from your house... and mold in winter in michigan means a substantial heat loss from the living space....stop the leaks thru the ceiling #1..add insulation..roof vents (you mean the mushroom type , right ?) are real close to no effect..a balanced vent system can reduce moisture .. but it has to be balanced between the soffits (source) and a good ridge vent , like Shingle Vent II as teh (exit)check your foundation for excess moisture... vent baths and kitchen, seal the ceiling and insulate the attic.....
*Kari,Venting an attic space is not rocket science, but neither is it as simple as cutting some holes and plunking in some vents. As Mike pointed out the venting has to be balanced, with the amount of venting roughly broken down to 50% high venting, (at or near the ridge) and 50% low venting. (at the soffit) If the amount of high venting greatly exceeds the amount of low venting, as it seems to have happened in your case, the attic space will be depressurised when a wind blows over the roof. Without low venting in place to provide replacement air, a partial vacuum builds in the attic space, and moisture rich interior air is pulled from the house through any leaks in the vapour barrier. Some of the worst mold and mildew problems I have seen are in attics that have had new roof vents installed! The owners, with great intentions, try and improve their homes but in the process make things worse. The worst offenders are usually the “Turbine” type whirly bird vents which do a great job of moving air but can create one hell of a low pressure area in an attic if additional low venting is not installed at the same time..
*The only thing that is new is a furnace i had installed last fall. It is vented through a new chimney liner. Im keeping the house about 10 degrees warmer ,(70 ), now that the old gravity heat furnace is gone. The new furnace also has a humidifier but i dont keep it turned up very high. The mold seems to be growing on 3 of the 4 sides of my roof. I was crawling around up there and the moisture seems to be the heavyest around the edges. My insulation is not covering the soffit area. Im putting in those soffit vents and hopefully that will help to dry it out. Other wise i dont know else what to do.Kari
*Kari:Since the only changes are (i) the new furnace and (ii) the humidifier, added moisture in the house air migrating to the attic and condensing on the roof sheathing is almost certainly the culprit.That moisture is i probably coming from the humidifier (the humdistats aren't very accurate or well clibrated) b BUT it could be from an improperly installed furnace flue: water vapor is a big part of furnace flue gases and excessive moisture ina home can be caused by flue problems. (Yeah, it was just installed, probably by "professionals." Unfortunately, sometinmes they make mistakes and sometimes they don't know what the heck they're doing --a couple of months ago I inspected a house in SE Michican with a "professional installation" where the flue cap had been installed directly on top of the flue so the flue gases all ended up in the house!?!)Although it's not very likely to be flue gases, if it is it can cause very serious health effects so please have trhe furnace installation and operation checked out: preferably by a Building Performance Institute trained Carbon Monoxide Analyst. (If youy're in SE Michigan, drop me an email and I'll send you some names.)
*kari, what kind of ceilings do you have in your home? I assume your house was built in the 20's, if you had a gravity furnace replaced. Is this a new problem since the furnace was replaced? or just the roof? or did they coincide? What kind of roof was torn off? Did you have wood shingles underneath asphalt and skip sheathing? Did they overlay the roof with OSB? OSB is like a vapor barrier, it doesn't allow moisture to pass through. I tend to agree that you have too much humidity in the house. You should be changing the humidity level with the outside temp. The colder it is the less humid your house should be. Soffit vents are definitly something you need. Jack and Bob have given you some good advise, make sure all the stuff that is supposed to vent is vented out of the roof, (and functioning) plumbing, bath fans and kitchen vents.
*Hmm...Gravity to forced air with a new humidifier. Sounds like the house is being pressurized with warm moist air.Do you have just a big central return?I tend to think venting is not the problem nor the solution here. If you're pumping warm moist air into the attic only massive venting efforts will get rid of it, but even then, plenty will condense on its way out. I think the new furnace and humidifier is way suspect. Turn off the humidifier for a while and inspect for air leakage into the attic with a smoke pencil.Didn't you guys learn anything from fred (chuckle)?
*This problem is new since the furnace instalation. My ceilings are both drywall and plaster. Two rooms were replaced with drywall. i turned off the humidifer 2 days ago and put in the vents. Im going to give it a few more days and go up into the attic again. 3 layers of ashvalt shingles were taken off and new tar paper and ashvalt shingles were installed. No sheathing need to be fixed. House was built in 1925.I did notice that the dry side of the atic has about 16" of insulation in it and the moist areas seem to have about 10". Maybe i need to even that out.thanks for the info, kari
*What is a smoke pencil? I will have to do some research.thanks, kari
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I was just up in my atic and saw mold growing on 3 of the 4 sides of my attic roof. I have 4 roof vents at the top of the roof and no soffit vents. I have been in this house 4 Michigan winters now and have never had this problem. Last summer i had a new roof (tear off) put on. They suggested installing soffit vents. Would soffit vents be the cure? The mold is starting to take over. Please help.