Ridge vent installed properly?

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  #1  
Old 08-04-09, 06:58 AM
J
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Ridge vent installed properly?

I recently had a mold problem in my attic. I took care of one major issue but the mold continued growing. So, I had a person from Servpro come look at the mold to remove it. Everything is ok as far as moisture in the attic. The humidity is a normal level, however it is incredibly hot (about 100* at 7PM). The guy looked at my ridge vent and wondered if it was venting correctly. We turned the light out and you can see a slight amount of light coming through it, but thats about it.

Can anyone tell me what I should be looking for to tell if it is venting properly?

Oh, an I should add, the mold seems to be growing right near the ridge vent....that is probably a clue of something?
 
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Old 08-04-09, 07:25 AM
B
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Hi j, If the mold is near the ridge vent, I would assume the moisture problem is up there as well. Is that where the mold was growing before the ridge vent, or is this a new location?

Not sure where you are, but 100 degrees is typically not very hot. I've seen temps of 140 and 160, that's HOT.

Now, here is the clue we need. He said the humidity was normal, but at what temperature. That's why they call it relative humidity. If it was 50% at 100 degrees it could reach 100% when the temp drops at night. It is a complex number that depends upon the house, outside, and basement moisture. For example, you could have a high moisture issue in the basement that is flowing up around vent pipes into the attic. Or simply live in a very humid area. Where are you anyway?

So, pull the rest of the numbers, outside, inside, and basement temp and humidity and the time of day you take the reading. Also what are your low temps at night.

Do you have any know water leaks or a house full of plants. Are your bathroom vents exhausted to the outside through side walls or soffit vents?

We will wait to here back.

Bud
 
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Old 08-04-09, 07:46 AM
J
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Hey Bud, thanks for the reply. Im am in western MD.

I guess you are right about the temperature. It was about 30 degrees warmer in the attic than outside. It was right about 53% at 100*. Ive watched humidity at different times of the day and it typically stays at that point or lower. Of course, if it is more humid outside, it will go up.

The bathroom fans...ug, what a saga. They are the reason for the orginal problem. They were vented into the eaves and all of the moisture was going right up against the underside of the roof sheathing, causing the mold. I extended the pipe and installed vents through the soffit to get them venting outside. The gentleman tested the moisture content of the roof sheathing at that point and others and said it was dry.

My biggest fear is that we will pay to clean the attic and the mold will come back.
 
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Old 08-07-09, 08:01 AM
J
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Dang it, forgot my numbers at home, but I can tell you Im not seeing anything out of the ordinary. The RH of the attic stays about the same as it is outside. The temps are of course higher and go down at night. The basement is cool and slightly humid. We have a dehumidifier running constantly to control that.

I just dont see where there is any issue. The thing that concerns me is the mold still growing. Even though I fixed what was the orginal problem, can the mold grow just based on the humidity from the outside air? There is always going to be some amount of humidity in the air.

Also, I did a little smoke test on the ridge vent. The smoke seemed to find its way up and out of the ridge vent. It wasnt like anything was sucking it out, but it did go to the vent.

Another interesting observation....the mold is ONLY on the north facing side of the roof. Not sure if that makes any difference.
 
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Old 08-07-09, 10:05 AM
B
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When you relocated the bath vents, you used soffit vents. Frequently this does not eliminate the moisture finding its way back into the attic, as the soffit vents are designed to pull air in, and the warm bath air wants to rise. Is the current mold anywhere near the new vents?

Now, you have to try and seperate "relative humidity RH" from "humidity H". The number you are using is RH therefore an attic temp of 100 degrees and 50% RH is a lot different than an outside temp of 80 degrees and 50%RH. Just as the outside air gets dry in the winter when you heat it, so should the attic air when it is heated. ie 80 degree 50%RH outside air should become something like 100 degree 40%RH once it enters the attic and heats up. So, if the RH is really remaining the same at a much higher temp, then moisture is being added somewhere. Here is a link to play with:
Temperature, Dewpoint, and Relative Humidity Calculator

Moisture is getting into your attic from somewhere, bath vents, moisture from basement, water leak (roof or other), fish aquariums, tons of house plants, condensation. 50% is about the threshold for mold growth. At 100 degrees and 50%RH, in the evening when temps drop, the RH will climb. At about 75 degrees, many things to consider, you could reach the dew point and see moisture on cooler surfaces. If you are getting confused it is ok, so am I.

Bud
 
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