Question

What can we do about condensation on our windows during the winter?

Asked by May Drinkwine
Putnam Station, NY

For many years in the winter time, we have terrible condensation on all of our windows throughout the house. One year we tried a dehumidifier (in one room) and that didn't help. I'm so tired of wiping up water on the windows. It has ruined some of the wood on the windows. What can I do???

Answer

Danny Kelly

Answered by Danny Kelly

Charlotte, NC

Kelly McArdle Construction

November 2, 2011

I would need a few answers before making a recommendation.

  • What is the relative humidity in your home and what type and age widows do you have?
  • Are they single paned or double?
  • How do you heat your home?

If you are getting condensation on your windows, the temperature of the glass is getting below the dew point related to your interior temperature and relative humidity.

Solving the problem

To solve this problem you either need to:

  • raise the temperature of the glass in your windows or
  • reduce the relative humidity inside your home OR
  • do both.

If you have old single pane windows it is going to be difficult to keep the window temp above dew point. I would consider replacing the windows with double (or triple) paned insulated glass.

If that is not in the budget, maybe consider installing exterior storm windows or shutters to isolate the window from the exterior.

Typically if you have forced air heat the supply registers are located above or below the windows to blow warm air onto the glass to keep it warm.

Reducing indoor humidity

I would purchase a hygrometer to measure the indoor humidity to see if it is elevated. In an ideal world we'd like to see it in the 30% - 50% range.

If it is elevated control humidity first at the point of the source:

  • run exhaust hood while cooking,
  • run exhaust fans during/after showers,
  • make sure your dryer is vented to the exterior.

Other options are providing fresh air ventilation through an HRV, run a whole house dehumidifier and try to keep the interior of your home a few degrees warmer.

 

For more information:

Read "Our aluminum-frame windows are harboring condensation and mold. Can you recommend window solutions for a damp environment?" a Q&A answered by Steve Saunders.

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