Winter Condensation Problems
Now that the winter is upon us I am getting condensation on my aluminum window frames, causing the appearance of a blackish mold. I know how to remove it, but I am more interested in preventing it. Should I get a dehumidifier, or are their other possibilities?
RT from Vancouver, BC
Your mission is to do one or both of two things: increase ventilation and/or decrease the level of moisture in the air any way you can. I know it is winter and we have been conditioned to abhor letting even the slightest bit of outside air in. However, the very tightness of our homes can cause the type of problem you are experiencing. Since the large amounts of moisture that we generate through normal living: washing, breathing and cooking: can't readily escape through the walls or around sealed doors, it instead becomes liquid (or freezes) on contact with cold surfaces: be they window glass or metal window frames.
Your main gripe is unique and virtually unknown in homes built in the last fifteen to twenty years: the full aluminum window frame. Though these frames are mechanically long-lived and pretty much indestructible, they are a disaster from an energy-consciousness point of view. All metals are horrible insulators in that they transmit heat at lightning speeds. The inside of the frame gets very cold because it is virtually sucking the heat from your room to the outside. I have seen metal window frames actually become coated with thick layers of ice as the winter progresses. Though the ice itself is not damaging, the effect of all that water on wood trim and walls when it thaws is no laughing matter!
You must ask yourself where the moisture is coming from. Sometimes, the source of moisture may not even be in the room. For example, moisture from a damp basement or crawlspace can rise within the walls and condense on the cold windows or metal frames. Condensation problems such as yours need a "shotgun" approach. A dehumidifier in the basement or in the affected room, opening a window a crack to let in cool and dry outside air, using the ventilator fan in the bathroom while taking a shower (or installing one if you don't have one), installing and using a vented stove range hood, etc. all help to minimize this problem.
That said, it may not be possible to totally eliminate the problem depending on the construction of your home, the type of windows, etc. Replacing the windows with double insulated glass can help too, since modern metal-framed windows use what is called a "thermal break": the inside and outside sections are separated by a less heat conductive material to prevent the heat-sucking mentioned earlier. As an added plus, the double-insulated glass used in these windows is warmer and less likely to cause condensation.
Installing inside storm windows can also help keep the warm, moist air from the metal frames and glass. You can get acrylic windows professionally installed or purchase do-it-yourself window kits at many home stores. An easier and less expensive way to get the benefits of interior storms with less cost is to install plastic "shrink-wrap" style interior storm windows. A thin plastic film is stretched across the window and attached by means of a special double-sided tape. The film is then shrunk tight and fairly wrinkle-free by heating it with a hair dryer or heat gun carefully so it doesn't melt! This protective layer of plastic film insulates by forming an air pocket and (as a fringe benefit) keeps the moist inside air away from the cold windows, decreasing condensation. If you don't mind the appearance, this could do the trick for you. Of course, these are not intended to be permanent, do not open and will have to be removed in the spring for ventilation.
copyright 2000 G.G. Alonzy
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