Condensation In Attic Ductwork

When the hot humid attic air contacts the cold duct or the cold duct boot the moisture in the air condenses on the cold surface just like the condensation that happens on a cold can of beer.

Condensation in attic ductwork.

Even though the air conditioning equipment appears to be operating normally humidity inside the house is between 60 and 65 and return ducts located in the attic show significant condensation. Even if the insulation layer is at the attic floor you ll probably be better off making the roof the pressure boundary of the house in which case the absolute moisture levels but not the temperature of the attic will track that of the conditioned space below which should reduce the condensation potential dramatically. Vapor barrier on the attic side of the duct s insulation is compromised. It s a natural process and similar to the way a chilled soda begins to sweat once you take it out of the refrigerator on a hot day.

So if you see unusual water staining on any of the ceilings in your home and the roofer has eliminated roof leaks it is likely coming from some fault with the duct system in your home. Condensation on air ducts can be a serious problem. The more the insulation compresses the less it can insulate your home. Condensation will begin to drip onto your attic insulation making it less effective at regulating temperatures inside your home.

Moisture goes right through the fiberglass insulation and condenses on the inner liner drips on ceiling below after building up. Ductwork located in an attic must be hung properly so that the insulation can do its job. Condensation from the ac ducts can drip onto your home s insulating materials. The 1 746 square foot house has r 19 insulation between the rafters and between r 15 and r 20 of rigid foam above the roof sheathing.

The colder the air is inside the duct the greater the chance of ductwork sweating. At the end of the day there are really only two causes for condensation on ductwork. Improperly insulated ductwork and excessive moisture in the air. Remember that condensation can cause all sorts of problems from leaks to mold infestation so take the time to address this problem as soon as you can.

It can also feed mold growth and cause ceiling joists to rot and sheetrock to disintegrate leading to unhealthy air quality in your home and the need for costly structural repairs. Both of these are easily treatable. Keep in mind that your insulation helps you save up to 10 on your yearly energy bills. As the humidity level rises outdoors condensation will gradually begin to form on the surface of your air conditioning ducts.

Let s say your ductwork is in your attic. There are two main ways to solve this problem. When ductwork is touching it forms a very cold spot where they are touching thus condensation begins. Over time condensation dripping from your ductwork onto attic insulation can cause it to compress which lowers its r value.