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Condensation of window frames not glass!

I have a brand new house with double pane single hung aluminum windows (builder's grade) My problem is that when the heater is on I have so much condensation on the window frames (not the glass) that water puddles on the window sill - so bad that it is starting to rot out my sheet rock on the side of the openings. My builder got with the AC installer and he suggested we add a fresh air vent to the hvac plenum in order to add some humidity. (that didn't make sense to me) That helped but the windows on both ends of the house are still condensating. My builder suggested setting the thermostat to 68 to see if it stopped the condensation. It condensated less but I still have water. Please help!

Re: Condensation of window frames not glass!

sounds like you have too high a relative humidity in the air. have you run a dehumidifier

Re: Condensation of window frames not glass!

This is a classic problem. Adding storm windows, heavy curtains (that touch the floor to reduce the chimney effect), reducing interior humidity are all steps to take. Controlling interior humidity is important: use the exhaust vent when showering, install a better, bigger exhaust vent in the bathroom. Use the microwave to boil water when possible. Dry clothes in the dryer not hang them in the basement.....

Re: Condensation of window frames not glass!

All of the above answers are accurate & helpful---however, there's another possible cause to condensation on or near the windows that could be dangerous & has to be checked out ASAP.

Sometimes a hole develops in the furnace combustion chamber at the heat exchanger, this allows some of the combustion products (water vapor, carbon monoxide) to enter the plenum and get into the living area via the forced air duct system; any family members experiencing flu-like symptoms, watery eyes, sore throat, trouble breathing, lethargy, etc. may be breathing combustion products.

I would suggest immediately buying a carbon monoxide detector/alarm at one of the home improvement stores---they sell for between $10-$30, and are a quick, effective way of being sure this problem doesn't exist.

Re: Condensation of window frames not glass!

Good suggestion on the CO detector, I have a couple Kidde Nighthawk units with the digital display. It will show a numeric reading that is too low to trigger the alarm units.

Also, the aluminum frames will conduct the cold. The builder grade units don't have the thermal break the higher price units have.

Re: Condensation of window frames not glass!

The aluminum around the window frame and the aluminum sashes conduct heat much faster than any of the surrounding materials, therefore it is colder and and moisture is going to condense on this surface much quicker than any surrounding materials, including the glass. It will be worse of there is any air leakage around the windows.

You could replace all the windows with wood/vinyl units. That would be expensive. Something that might work, I've never tried it so I'm not sure it would, but you could look at some wood or PVC trim pieces to glue to the exposed aluminum frame. You could use a (non silicone) latex caulk so that if it didn't work, you could remove it. Basically you would be blocking the air in the room from touching the aluminum frame. You can't do anything about the sash though, you may still get condensation on it.

If you can attach some wood or PVC trim to cover the outside exposed aluminum frame, it might also help keep the aluminum warmer. Also make sure there no air leaks around the movable sash, you can always caulk around the fixed sash if needed.

I think if this is done right, it could improve the appearance of the windows as well.

Re: Condensation of window frames not glass!

Thanks for sharing this wonderful post.


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