vapor barrier in attic

Old 11-12-04, 05:52 AM
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vapor barrier in attic

hi, my windows sweat something afull. the house is 30 years old,ranch style.hip roof on ends,vents on ends and also perferated soffit. i believe the trouble is in the insulation.i have 6 inch unfaced fiberglass, no vapor barrier. what's the best way to fix it?
Old 11-12-04, 07:07 AM
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Don't see what having no v/b in the attic has to do with your windows sweating. Are you getting any wet spots in the ceiling or ice inside the attic? Those would be the signs that moisture is getting in and condensing in the cold attic. You can just pull up the fiberglass and place a 4 mil poly sheet under it. That'll stop vapor from penetrating
Old 11-13-04, 05:55 PM
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I don't have any wet spots on the ceilings or walls,all the windows in the house sweat something terrible,they are anderson theropanes,they have done this since the house was built,any ideas?
Old 11-13-04, 06:13 PM
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Condensation on windows

Condensation on windows is usually indicative of too high humidity level in the home. When warm, humid air settles on cold surfaces, it produces condensation (sweat) like on the outside of a cold beverage glass. Condensation on windows is usually not the fault of the window unless window seals have failed. Today homes are built much tighter and there is not as much air flow, so humidity tends to be a major issue if home is not well-ventilated.

There are some things you can do to reduce condensation on windows. Keep draperies or blinds open in order to increase air flow around windows. Turn on exhaust fans a few minutes before cooking and bathing so fan can create air flow before you introduce an increase in humidity and continue to run for 30 minutes or so after cooking and bathing to exhaust humidity. Make sure gas burners and clothes dryers vent to outdoors. Unvented gas heaters also add humidity to the air. Turn off humidifier on furnace or any other humidifiers you have in the home.

Make sure attic is well ventilated. Make sure your crawl space vents are open and you have enough of them. Crawl space should be dry and covered with polypropylene (plastic) vapor retarder to keep humidity from rising through subfloor. If you have a fireplace, open damper to allow an escape for humid air.

The only way to know what your humidity level is to measure with a hygrometer. These are sold where they sell thermometers. Temperature should be maintained between 35%-55%. Anything over 55%, you need to run dehumidifiers. Humidity can vary from room to room, usually higher in kitchen and bathrooms. Fans will increase air flow and improve ventilation.

Vapor barrier in attic goes beneath insulation in order to keep warm, humid air from rising into attic where it can cause condensation problems there. Inspect attic to make sure there are no moisture problems there and that you have adequate ventilation.

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