rust in lights = ventilation issue?


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Old 09-08-11, 06:44 PM
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rust in lights = ventilation issue?

two story home built in 2003 with a two story entry and family room on the main level. for years i have noticed what i thought was dirt build up inside our flush mounted ceiling lights. recently we had some nasty wind driven rain that resulted in a slow drip coming from a light on the 2nd level.

pulled the dome cover, it was full of rust. this is one of those nipple looking dome lights with the center pillar/screw for the glass. that piece is totally rusted. no water damage to the ceiling or any drywall anywhere in the house. some of the metal parts of the light are rusted as well. pulled the dome from the other lights and the same thing, just not as bad. in fact, a simillar light on the first level too.

i poked my head up into the attic, but it was at dusk and sorta dark. i did not see any water damage or signs of mold. i need to go back up there in day light and move the insulation around where the ceiling lights and inspect that. maybe this weekend.

any ideas or direction for me? much thanks.
 
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Old 09-08-11, 08:02 PM
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What is the rh in your house in summer and winter?
 
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Old 09-08-11, 08:11 PM
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I would suspect that the light is cold and that water is condensing on it when it is cold just like it would on a cold can of beer.

Either the light isn't an air proof IC, or it needs an air barrier /more insulation over it. Some ppl will build a foam box around their lights to enclose them and make them warmer, but you need to know more about the specifications of your existing light before you start doing something like that.
 
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Old 09-09-11, 04:56 AM
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Also when you pull back the insulation check to see if there is vapor barrier behind the electrical box that is tape sealed or otherwise with the ceiling poly vapor barrier assuming you are living in a northern climate. Is the box metal or plastic also?
 
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Old 09-10-11, 10:21 AM
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not sure what RH Factor means.

this is all the ceilling mounted lights on the second level. this one is worse than the others and the only to actually drip water during a heavy rain storm. ill get up there today to determine what i got going on with the one light. thanks for the tips.
 
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Old 09-10-11, 10:58 AM
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Second floor means the lights are exposed to the cold attic as mentioned.

RH is relative humidity. You should pick up an inexpensive meter to know that number.

During a heavy rain the RH is usually around 100%, thus chances of condensation increase.

A plastic vapor barrier over the electrical box for the lights could provide a surface for condensation if the insulation above it is not sufficient.

Be sure your bath and dryer vents are directed to the outside and not the attic.

Bud
 
 

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