Condensation on Skylight

[HotChick]

Hi,
What would cause condensation on a skylight? Never had this issue before until my a/c was replaced.

Thanks.

[second opinion]

Hi,
What would cause condensation on a skylight? Never had this issue before until my a/c was replaced.

Thanks.

Breathing to fast!

Inside or out? There must be cold air blowing directly on the skylight but sounds unusual, since the skylight is in the hottest spot in the house.

[jpsmith1cm]

Hi,
What would cause condensation on a skylight? Never had this issue before until my a/c was replaced.

Thanks.

The simple answer is that the temperature of the skylight is below the dewpoint of the surrounding air.

The WHY becomes a much more difficult question to answer.

[Shophound]

Which side of the glass is seeing condensation is a very important piece of information to know. If it's on the exterior side, and at night, you're keeping the inside of your house very cool, or there is supply air blowing straight onto the skylight. If it's on the interior side of the skylight, and it's at night, then it could be night sky radiant cooling dropping the temperature of the skylight glass below the dew point of the interior air.

[HotChick]

Hi...they didn't seal my duct work and one of them is in the attic space that channels around the sky light...so...could it be blowing there? I assume that is what is the problem...that or they blocked the sophets with ducts and the window can't breath...or did i just make that up ? Don't know if that can happen.

[HotChick]

Won't I get mildew along the window frame? I had central a/c before. They changed the duct work. Never had condensation.

[beenthere]

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[Shophound]

Again, is the condensation occurring on the inside of the skylight, or outside?

[HotChick]

Hi
I couldn't tell bc it was getting dark out. The window is pretty high up and behind a screen and it was all fogged up. It was 65 outside (it had cooled off around this time of day). I think it was inside but I can't say for sure.

See the photos of skylight here, it is tunneled up through a sophet, and you'll see that ducts are run all around three sides of it (and the side there are no ducts is an outside wall), kind of closing it off away from the rest of the attic... which is why I'm concerned that they are either blocking the windows "breathing" space or something, OR, they are all leaking air into this space.

http://s1163.photobucket.com/albums/q546/hotchickphoto/

I will try and see if I can tell next time it happens. Since the window opens I may be able to figure it out.

I have another question maybe you guys can answer. My attic fan is in my higher attic. My house is split and this skylight is in my lower attic. There was big "doorway" type space between the two attic levels that is now 75% blocked by flex duct.

Will i end up needing to put an attic fan on the other side of the house now? Me no understand exactly what the attic fan does but I feel like what ever it does, it can't do for the lower half of the house anymore...or...maybe bc its in the higher half its not a problem. Dunno