Condensation on Double Pane windows

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  #1  
Old 01-03-09, 09:54 PM
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Condensation on Double Pane windows

We looked at a 6-year old Log house today to possibly purchase and found a lot of condensation on all the windows. Some facts we know about the situation:
1. The house seemed nearly empty with the inside temperature of about 65-68F
2. A cold day in Alaska. Outdoor temperatures were -30F
3. the house has three separate heating systems: 1) ground floor with hot water circulating in tubes under the flooring, 2) second floor has radiant heat, 3) a gas stove on the first floor.
4. The design is an open space all around the house
5. All window were nearly equally covered with ice in the bottom section of the window (with visible mold under the ice)
6. The gas stove heater draws outside air for combustion

We understand the high difference in outdoor/indoor tempartures and the fact the the house is nearly empty may play a role in the excessive condenstation.
The question is.... what do we need to ask and what do we need to change to remedy the situation.
 
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Old 01-03-09, 10:04 PM
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Condensation on windows in the heating season is caused by high Humidity in the home. Increase ventilation and make sure you use your bath and kitchen exhaust fans.
 
  #3  
Old 01-03-09, 10:47 PM
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Indoor humidity should be at 35-55% year round ( measure with hygrometer sold where thermometers are sold). Humidity levels tend to vary from room to room. If humidity is high, install dehumidfiers and run fans for improved air circulation.

Make sure house is adequately ventiliated and is properly insulated. Make sure all stoves, bathrooms, and dryer vents are vented to outdoors and not into attic or other space. Inspect attic to assure you have adequate insulation and ventilation for the area. Seal all gaps where warm, humid air leaks into attic area where temp should be equal to outdoor temp.

With adequate insulation, ventilation and dehumidifiers and fans running for improved air circulation, you can control condensation issues. Condensation occurs when warm, humid air hits cold surfaces and condenses. Opening up window treatments to allow air and heat to circulate can provide minimize condensation.

What do you need to ask? Fuel bills for the last 12+ months. Any issues with condensation? Mold? Mildew? Why are you seeing these issues?

Hire a home inspector. Discuss issues. The inspector should provide the clues for which you look. If you have not signed the contract and plan to, then put in a contingency clause re: pending inspector. Hire a real estate attorney to cover your butt if something goes wrong.
 
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Old 01-03-09, 11:02 PM
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Thank you Twelvepole for your comments. We will definately hire an inspector AND an attorney.
Since there is a lot of ice in the bottom of the windows do you think there is a significant amount of air flow from the window seals? The house has been rated '4 star plus'. But I wonder if that was a summer time rating and the seals behaved differently than at -30F.
 
  #5  
Old 01-04-09, 12:37 AM
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Never lived where temps reached such lows that you mention. I do have a mountain cabin in WV where it is not unusual to get 3+ feet of snow in ski season. Now I am old and with heart disease, I lack the adventure in my heart to weather the trip to my beloved cabin and the 4 1/2 drive.

I don't have your problems despite lack of insulation, dropped ceiling, loss of heat, etc. Never dealt with -30 degrees. It sometimes gets to minus degrees there, but not your extremes.

Can't hazard a guess re: your windows and environmental conditions. Can't hazard a guess re: insulation, attic ventilation, heating, humidity levels, window quality, fit, and sealing,etc. I have no idea what Alaska conditions are. Ask Palin.

A professional home inspector is a good start, but no guarantee, and a real estate attorney is also a definite bonus.

It is so difficult to provide advice without seeing the property and offering an inspector's advice. Hats off to you for hiring a pro inspector and real estate attorney.
 
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Old 01-04-09, 05:55 AM
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Hi EBK,
If it has a 4 star rating, then someone did an energy audit/rating. Alaska is very advanced in their energy rating procedures with their own software (Akwarm) and standards. Of course few of us down here ever have to deal with permafrost, thus their custom approach.

But, see if you can get your hands on that audit, it will be very informative.

As for the frost, excluding Alaska, I'm up north and even very good windows will get moisture and frost. My greater concern would be the log construction. Even the best ones usually don't have the insulating capabilities we needed four months ago. Prices have come down now, but if they go up again, there is no place to add extra insulation.

Enjoy
Bud
 
  #7  
Old 01-04-09, 07:59 AM
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At -30 the dewpoint is extremely low so it would not take alot of humidity to condense. That being said something doesn't seem right....I'd be leary of the hot water tubes on the ground floor heating system. This could be leaking and adding to the humidity (among other problems). Second, is the ice on the windows inside or outside? If it's inside, run - don't walk - away from that house as fast as you can. Ultimately its your call but I would not enter into a deal unless you get a thorough inspection and some guarantees from the seller.
 
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Old 01-04-09, 08:53 AM
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I think some off you are going a little to far. It was stated that home was almost empty! To me this means no body has been their for awhile. That would lead to decreased ventilation, which would raise the RH in the home. A simply test for RH would be all that is needed to tell if it is high. At -30 I would say that you would like the RH to be about 20%. At this level you might still have some condensation but any lower might cause the wood to dry out. My Thoughts.
 
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