Condensation on skylights

[removeb4flight]

My new shop has 4 skylights, which is great for natural light. These are the aluminum curb types mounted to a comp shingle roof. Now that it is winter, and with snow on the roof, the cold aluminum is condensing a lot of moisture. The shop is barely heated to 55 degrees. My ceiling is drywalled and has R-19 insulation above it, so the heated air rises to the top of the light wells. I may have made this problem worse by bringing in some wet wood 2 days ago which has dried in the shop. Is there any good way to insulate the aluminum curbs to cut down on the condensation?

[Wgoodrich]

If you bought a less expensive skylight that is not a good quality double insulated glass the glass will condensate commonly.

If you have a good double insulated glass but condensation appears on the metal only which is also very common then you have a different problem.

If you have the second option good insulated glass quality that does not condensate but the metal only is condensating then you can paint with a rubber paint putting on many layers of the rubber paint. This often stops the cold metal hitting the warm air inside limiting your condensation.

Either condition above mentioned can be helped by installing a small fan from the ceiling that will blow air constantly across that skylight thus drying out the moisture by air circulation. You would have to install a fan on each window using this trick. This is not a cure but will reduce the condensation concern.

Try buying a humidistat to find the moisture level in your shop ambient area. If it is around 50 % realitive humidity you only have a skylight concern to address.

Hope this helps

Wg

[removeb4flight]

Thanks for the advice. It is the metal curb which is the problem. The plastic is double walled. I will try the rubber paint insulation idea. I think I had a lot of condensed moisture because I was running a small propane heater, the type that has a catalytic screen, to heat the shop. No venting caused water vapor to build up inside the shop.

[Wgoodrich]

That rubber paint installed thick should help and can be installed outside or inside. The goal is to stop the convection between hot inside and cold outside causing the condensation. Break the metal transfer transmittal of that heat meets cold and it should reduce the condensation.

Good Luck

Wg