Just the other day someone asked me, “Robert, I know Seattle is wet and all, but why do I have puddles inside my windows?”
Unless you have experienced and out and out window failure and water is actually running in and behind the window, the likely cause is condensation on the inside of the window and frames. This is actually very common with older windows with metal frames. With our damp Seattle air, it is very common that on cold damp days that you can see water condensing and puddling up inside old or low quality windows.
What happens is that when the weather is cold outside and you have warm moist air inside your home, water will condense out on the cold edges of the window. This is exactly the same thing that happens when you fill a glass with ice water on a hot summer day. The warm moist air contacts the cold glass and water condenses out forming drops of water which run down to the bottom of your windows, forming those puddles you are seeing.
In this case though the water that is condensing out is running down your window, puddling up and eventually soaking into your window sill. This can lead to two main problems. The first is deterioration of the window frames. Over time the repeated moisture can cause the frames to rot and disintegrate. The other issue, and one that is extremely common in the Seattle area is mold growth.
Mold around windows is commonly seen as patches of black dots around the wettest areas. While you may not think that this small amount of mold is bad for you, consider that this is simply the mold that you can see and that they send off spores at night, typically when we are asleep in our bedrooms. Sounds pleasant doesn’t it?
What can you do about condensation on your windows?
The first thing you can do is lower the relative humidity in your home. I know that can be difficult to do during our wet Seattle Winters, bur there are a few places to start with. Check to ensure that bathrooms are properly vented. Showers generate a massive amount of moisture and this can spread throughout your home.
Inspect your dryer vent and confirm that it is correctly hooked up and functioning. You may also want to consider the use of a dehumidifier to reduce the total amount of moisture in the air.
The most direct way to solve the issue is to stop the condensation at the source; the place where water is condensing. Replacing your low efficiency windows with high quality windows will generally solve the problem. Older windows allow more of that cold from the outside through and magnify the moisture problem. Newer vinyl windows with insulated frames reduce or eliminate condensation issues. Also look for windows with some form of ‘warm edge technology’.
Traditional windows have metal spacers separating the panes of glass. This metal acts as a short circuit transferring the cold through the glass to the inside leading to condensation around the edged of the window frame.
Whatever you do, I strongly encourage you to take some action to prevent condensation from repeatedly forming in your window sills. Even if you live in Seattle, you shouldn’t have puddles inside your windows.
