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Attic condensation Leak exhaust duct

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DennisCTB
Join Date: Nov 1998
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2010-01-07          167936

I have a two story family room where I am getting an occasional leak out of one of the recessed lights. There is no leak when it rains but rather the leaks occur at random times when it has not rained for even a week or two.

The amount of water is just enough to wet a 2 inch circle on the carpet, like maybe a quarter of a cup. It does not have much of an oder either though might have a little yellow tint.

The leak comes thru one of the recessed lights. It is a fully metal square boxed recessed light between the ceiling joists, the attic is above the light so it is fully accessible from above. When I go into the attic to inspect the light there is no water on the light or anywhere near it when I remove the insulation. I have mouse and rat poison in the attic that I placed up there in the fall, a small portion was eaten shortly after I put it up there.

I don't see any mouse dropings near the fixture. I don't see any way to get into the can for any critter, though it does not take much for a mouse. I also banged on the can and got no animal reaction.

Any ideas?


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Murf
Join Date: Dec 1999
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2010-01-07          167937

Yup, it's a pretty common problem.

First off, don't worry about your roof, it's fine. The problem is one of condensation. The light gets warm when it's on and the air in the attic is cold and likely very damp. The combination causes a great deal of condensation to form at certain times. This is likely aggravated by warm air leaking up around the light itself and into the attic. That leak in the vapour barrier is where the water is coming back in.

I'm willing to bet if you double check the vapour barrier and add more insulation above the light the problem will go away.


Best of luck. ....

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s chrand
Join Date: Aug 2004
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2010-01-07          167938

condensation?
maybe it's not fully insulated around the fixture, or a small break in the insulation, and you're cooking spaghetti which puts a lot of moisture in the air, and the heat from the light bulb is making the light housing warm, allowing the moisture to condense on the inside of the housing, and sometimes there is enough of it to actually drip.
can you get to the bulb side of the fixture to inspect it the next time it happens?
just a thought...


darn... i see that murf just beat me to it! ....

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DennisCTB
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2010-01-07          167939

interesting, I have 3 lights in that area, at least one has insulation on top but not the dripping one. We have lived in the house for 12 yrs since it was built and never had this happen. Does warm very dry house air exacerbate the condensation? As I have not been running the humidifiers.

I will see if I have piece of insulation to put on top and see what happens. ....

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hardwood
Join Date: Dec 2002
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2010-01-07          167940

OK, I really don't have an off hand cure for dripping lights, but MURF!!! Vapour, is that Canadian slang for when you are across the table from a very proper lady or something??? LOL!!! ....

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earthwrks
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2010-01-07          167941

I agree with Murf. By the sounds of it you have good cross ventilation which is why you're getting condensation. Just to be sure, verify that the outside air temp is the same or very close to the attic air--the roof structure is only meant to keep the elements off the house not provide insulation or keep heat in or out.

A friend had a new home built that had 2" of ice on the inside of the roof sheathing and less in other places. His dryer vent and bath vents exited into that are where ice was thickest. Mold was forming too from past years and the sheathing was sagging.

A 2500sq ft home with only three roof vents and no soffit vents. Long story short the builder tripled the number of vents and the problem went away. Imagine that.

Dennis when we have can lights in an attic we build a box around it about 18" sq made of 2x6 then loosely cover with insulation. Just for safety in casesome one puts a too hot of bulb in the fixture.





....

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auerbach
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2010-01-08          167948

One part of the explanation is, as said, condensation. The other is heat conductivity. There's less liklihood of condensation on insulative materials like wood or fabric, more likely on conductive ones like glass or metal.

So one solution is to make the metal less conductive by packing insulation around it. The other is to get a humidistat for the area, and if it shows high (generally above 30% relative humidity), control it with ventilation or a fan. (Without getting into dew-point measurement, the colder it is outside, the lower the humidity has to be in order to prevent condensation.)

Third, if the problem only occurs after the light has been on, leave it off, replace the bulb with a compact fluorescent, or (very carefully) install a heat deflector above the bulb such as aluminum foil. ....

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kthompson
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2010-01-09          167971

Depending on air movement it will do this without the light on. Just the difference in the in house temp and the attice temp. Air leaks around recesssed lighting happens. Here it was (not sure if still is) code did not allow insulation over recessed lighting due to heat built up.

Made a mistake when installing exhaust duct in one bath room with non insulated metal running straight up. No problem except when attic is cold (about freezing or colder) then the can be a good amount of dripping on top of toilet seat. Made us wonder about the puddles on top of the seat until one day the water dropped on one of us. ....

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earthwrks
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2010-01-09          167972

Kenny that vent pipe should exhaust into a roof vent or the air will still condense in the attic like I mentioned earlier. Insulating the pipe does as you say help.

And that puddling on thr seat thing---yer supposta lift the seat.

Speaking of toilets, didn't you tell me that one time your bathroom caught fire? But...luckily you put it out before it got the to house. Lol ....

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kthompson
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2010-01-11          167987

Quote:
Originally Posted by earthwrks | view 167972
Kenny that vent pipe should exhaust into a roof vent or the air will still condense in the attic like I mentioned earlier. Insulating the pipe does as you say help.And that puddling on thr seat thing---yer supposta lift the seat.Speaking of toilets, didn't you tell me that one time your bathroom caught fire? But...luckily you put it out before it got the to house. Lol


In our normal warm weather venting to the attic works well. Two of ours vent to the eaves which allows any condesition to drip or ice up as temp may be on where either will cause no damage. Our bathroon has a very high roof line above it and it vents to outside vent but the bare metal the temp had already dropped before it gets outside.

As to the fire you are correct, but you never did tell me was what was the cause of the fire...what you were smoking or what you were releasing. Has all the hair grown back?

Well I could have said yes, we place all outhouses in Washington. You pick the one you like best. ....

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hardwood
Join Date: Dec 2002
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2010-01-11          167989

The plumbing system in our farm house has two sewer vents thru the roof that are both part of the same system.
Both go into the attic as 1 1/2 PVC then are stepped up to 3 in. before they go thru the roof, they are at opposite ends of the house. Whenever the wind blew more than just a breeze it sounded like a non stop steam train whistle till one or the other would frost shut just above the roof. After figuring out the reason for all this I put another trap in the system that kept the air from whistling thru from one vent to the other. I'm a long way from being a sewer vent expert, but I think it was caused by the wind currents going over the roof causing there to be a bit more or less siphon effect on a vent pipe??? ....

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kwschumm
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2010-01-11          167991

I would bet that most building codes in the US would frown on any venting to the attic.
....

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cutter
Join Date: Feb 2000
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2010-01-12          168010

I'm a bit confused re the freezing shut of the vent at the roofline. Only air in there so unless you mean covered with snow, it should not freeze shut.

In high winds the vents will pull a vacuum, they actually suck the water down in my toilets a bit on those occasions, no comments please :)

I have never heard sewer vents whistle, but given the location, I would guess it could happen. Most likely you could place some sort of cap on them that would disrupt the wind current and still allow them to operate effectively.

....

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hardwood
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2010-01-13          168011

Cutter;
Yes, it seemed the moisture in the vent air would freeze to the inside of the vent pipe above the roof line till it was blocked. The train whisle sound did stop when a vent froze shut, but we could then smell sewer gas in the house. This happened several times the first winter, and which one froze seemed to depend on the direction of the wind. After the trap was put in stopping the free flow of air from one vent to tne other it hasn't happened again in 13 winters since. Frank. ....

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kthompson
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2010-01-14          168048

I may not fully be in understanding of Cutter but I do agree it does not seem like there would be enough moisture in a vent pipe that has mostly gases in it to freeze shut. But I learned long ago just cause I have not seen it happen does not mean it can not.

Ken as to Codes not liking venting into attic...all I can say is some points do vary a good bit. One that surprises me at least 10 years back when our house was built was low voltage lines had nothing related to them. Don't think they would have cared if on top of studs for sheet rock to have laid on them. Matter of fact electrician ran one door bell wire that way and it was me who required it to be moved not code. ....

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Murf
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2010-01-14          168052

Up here lots of folks have electric heater cables in the vent stack to keep them free all winter.

Any time you have warm humid air exposed to cold air it will condense and freeze, that builds up until it's blocked solid.

You either heat the vent stack or put up with the gurgling till spring.

Best of luck.
....

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DennisCTB
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2010-01-15          168057

Ok guys, I did not change a thing and I have not had a leak for a couple of weeks now, add that to the 13 years of no leaks and I still think it is wierd, even with the condensation theories, why so spotty?

Anyway gotta count your blessings :)

Dennis ....

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kthompson
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2010-01-15          168059

Colder air has lower moisture levels. You need just the right temp and moisture level for it to happen enough to show up. My guess is if you were to place say a tissue on the floor you would notice the sign of a few drops on it but not enough to show on the carpet.

Or it is due to global warming and since this winter is global cooling it happened but I like my first thought better. ....

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Murf
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2010-01-15          168061

Dennis, maybe it's those Turkey Vultures you had a problem with, now they're playing games, messing with you trying to get even for you chasing them off.

LOL LOL LOL



Best of luck. ....

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cutter
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2010-01-15          168062

I was thinking more along the lines of mice having parties up there and using the "can" to relieve themselves :) ....

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earthwrks
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2010-01-15          168064

Kenny I know yer used to breathing a lot of hot air-- ahem--, but cold air does have moisture in it just like hot air.

Right now it is 36 out and the humidity level is 89%. Last week here it was in the single digits and the humidity level was 99%.

You may be thinking of air density. But even then cold air is much, much denser. But that isn't related to moisture content. ....

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kthompson
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2010-01-16          168087


"Relatively Speaking …
Relative humidity (RH) is the percent of moisture actually in the air compared to the maximum amount of moisture the air can hold at that temperature. Cold air can hold less moisture than warm air. At 70ºF, air can hold as much as 12 times the amount of moisture as 10ºF air. That’s why it’s usually more humid in the hot summer months."


Ole Jeff the above quote is found at the link. The same is found in many post on the internet, NASA's was little too long to post.

But seriously you know winter air is dryer, that is why your skin has such a problem being dry and the large jump in sales of all kinds of creams. The fact cold air has 89% relative humidity could be 100% true but if the air was warmed that 89% would begin to drop as warmed. That is why as warm air goes out my exhaust pipe that is not insulated it sweats or condenses and drips into my house. Just think about where most rain (maybe all I don't know that) comes from. You have a warm air mass that meets a cold air mass. If the warm air mass has a high relative humidity you will have rain or snow. Of course warm air and cold air can be dry or full of moisture as it relates to their tempature.

Now HOT Air from Washington may be a different issue. ....


Link:   

Click Here


 
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kthompson
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2010-02-13          168594

Dennis, did you find the source of the "leak"? ....

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DennisCTB
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2012-07-09          184189

Update, still no more leaks from that fixture. Now convinced that the culprit was the fact that I have a central exhaust system fro all the bathrooms so a galvanized pipe runs across the attic ceiling above the three light fixtures.

At the time both of my kids would take very very very long hot showers. That must of caused the condensation in the attic.

Since then they have, with constant coaching from me, shortened the shower time :) ....

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kthompson
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2012-07-09          184190

When we built we install large capacity exhaust fans in our bathrooms. We also used galvanize pipe and with two no issues. But the main bathroom the pipe was run straight up for a few feet. All was fine till we started getting water drops out of our fan. Took a little bit of thinking to realize it was the hot moisture laden air hitting the cold attic air and it really turn the moisture into rain. So we learned in the winter time it make good energy sense to not run the exhaust fan for steam removal. It was not just moisture on the inside of the pipe but it also was on the outside of the uninsulated pipe and that was staining out ceiling. ....

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