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Preventing Condensation on Pipes and Metal Surfaces Q&A

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Dear NH,

In my basement, there is significant condensation build up on the cold water pipes. There is enough water dripping to actually create puddles in the basement floor! Is a dehumidifier is the solution, or should the pipes be insulated or covered? Thanks.

DM

Dear DM,

Both are recommended. If you cover all the pipes with insulation, preferably the foam type (instead of fiberglass wrap), you will eliminate contact between the damp basement air and the cold pipes. Wrap all joints with duct tape to be sure of a good seal. The reason I don't recommend the
fiberglass-type pipe wrap is because in high humidity conditions it can become soggy from the condensation, lose insulation value, and become mildewed.

However, you still will have damp basement air, which will cause mildew and damage anything you store in the basement. The dehumidifier will lessen the humidity and therefore reduce the damage. However, don't expect the humidifier to eliminate the moisture enough to prevent condensation on
pipes. The pipe insulation is still a must!

If you have a well pressure tank that has condensation on it, consider wrapping it with an insulating blanket such as those commonly used on hot water heaters. Try to purchase a flexible plastic foam blanket if you can find one. But, if necessary, it may be better to use fiberglass than nothing! Just carefully wrap the fiberglass with plastic sheeting to act as a vapor barrier from the damp basement air.


Dear NH,

I love your site, but I cannot find the answer to my problem. I am getting condensation on all my aluminum window frames, causing black mold. What can I do to prevent this... a dehumidifier or what?

RT in Vancouver, B.C,

Your mission is to seal the windows more tightly and/or decrease the level of moisture in the room air any way you can.

If your windows are leaking outside air, this air could be cooling the frames sufficiently to produce condensation. Weatherstripping at the locations where leaks are felt can be beneficial and in some cases may be the only effort needed to stop the condensation. However, if your aluminum frames are continuous from inside to outside, they are likely acting as conductors for the cold, leaving you with the options of either reducing the moisture in the air or installing some barrier inside to keep room air away from the frames.

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. So as you see, condensation problems need a "shotgun" approach. For example, a dehumidifier in the basement or in the affected room, opening a window a crack to let in cool dry outside air (I know if sounds like a contradiction, but sometimes it is worth a try), using the ventilator fan in the bathroom while taking a shower, installing and using a vented stove range hood, etc., can all help to minimize this problem.

That having been 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 the inner pane is warmer and less likely to attract condensation.

A more economical (albeit temporary) alternative would be to install plastic "shrink-wrap" style interior storm windows with good result. This temporary shield will keep moist inside air away from the cold windows and frames, plus decrease air infiltration. If you don't mind the appearance (which is actually not too bad if the installation is done neatly), this could do the trick for you.


Dear NH,

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

RT,

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.


Dear NH,

My daughter and her husband who live in Northern Indiana have a terrible moisture problem. They live in a tri-level house. They are noticing gray-black discoloration of the ceilings in all of the three rooms on their upper level. Touching the areas, they are moist. Their windows also have condensation.

Looking in the attic, there are areas where the insulation is wet, and mold or mildew shows on the rafters. I suppose a roof leak is possible, but the moisture is so widespread, my inclination is against such. Would poor attic ventilation cause this severe a problem? They also have a humidifier on their furnace. Would such create this problem?

What must they do? Pull out the insulation? Replace the damp ceiling drywall? Is it possible to kill all the mildew, etc in the attic? A health concern if they don't? Can a general remodeling contractor properly assess the problem? Or do we need to contact someone more specialized? Help!!

KLV from Columbus, IN

KLV,

Mildew is always a potential health hazard, though susceptibility to mildew from an allergic standpoint varies widely from person to person.  An inspection of the attic and roof is certainly important, though such widespread dampness is not usually caused by localized roof leakage.  I would recommend turning off the humidifier immediately.

Do they have natural gas heating? If so, leakage in the vent pipes can release large amounts of moisture into the air. This is also a carbon monoxide hazard. Have any venting examined for leaks if this applies. Unvented gas appliances such as space heaters and stoves also emit large amounts of moisture into the air.

If the insulation is truly soaked, it must be torn out. In your area is will never dry out during the winter and will continue to cause problems.

By all means check the attic for proper ventilation. Depending on the existing ventilation, a powered fan might be necessary at least part of the year. I have lot of information on ventilation at this URL:
http://www.naturalhandyman.com/iip/infattfan/infattfan3a.html

High levels of moisture in a basement or crawlspace rise into the living space and can cause problems. You can find some solutions at:
http://www.naturalhandyman.com/iip/infxtra/infsweat.html

Depending on your (or their) skills, most suggested remedies are of the do-it-yourself genre. Whether or not any specific contractor has the knowledge to assess your problem will require a little homework on your part. You may not have any local contractors with expertise in ventilation, but that does not mean that they cannot solve your problem You may have to take a "hands-on" approach and educate yourself to be sure the problem is completely solved!


Dear NH,

Regarding the letter (in the last newsletter) about excessive moisture in the home, the owner should have the heat exchanger on their furnace checked. I am a former HVAC technician and sudden excessive humidity can be a sign of bad heat exchanger or blocked vent pipe. Both can be a deadly hazard.

You mentioned checking for leakage in the vent pipes. They should also check for "blockage" in the vent pipes. If the chimney is not screened, birds can get down in the chimney and end up blocking the vent pipe. While the furnace is operating, they should hold a lit match in front of the draft diverter. The flame should be drawn towards the draft diverter. If the flame is directed away from the furnace, there is a venting problem.

Another thing that should be checked for is bathroom exhaust fans vented directly into the attic. This can exist for years without causing a noticeable problem until 'suddenly', the child(ren) become teenagers and start taking frequent, long showers depositing large amounts of hot moist air in a cold attic.

I hope my comments are helpful. I appreciate your essays. They are thoughtful, often thought provoking, enjoyable and I look forward to them.

GB

GB,

Thanks for your insights. I'll pass them on! Hopefully the writer took my advice and had a HVAC pro (such as yourself) in to evaluate the furnace!

NH

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