Storm Window Condensation

By HomeAdvisor

Updated August 8, 2016

Storm windows

Though there are many modern ways to make a home more efficient, storm window installation is one of the most practical in many scenarios. Especially in older homes where owners might want to keep original windows in tact, or in some cases are required by ordinance to do so, storm windows can reduce heating and cooling costs, increase overall efficiency, and prevent drafts that can make a room feel uncomfortable.

There are, however, a few problems that can occur with this type of window. One of the most common issues has to do with excessive condensation during the winter. This can have an effect not just on the visual appearance of the window during cold weather, but on the actual structure of your windows, too.

Possible Causes of Storm Window Condensation

In many cases, storm window condensation is caused not by the window itself, but by some other factor in the home. Most professionals would put the “normal” range of humidity in a home somewhere between 30 and 40 percent. Under these conditions, newly installed storm windows shouldn’t be having problems with excessive condensation. If your home has humidity levels of more than 40 percent, when the temperature gets cold, condensation is likely to occur no matter what brand you buy or who does the installation.

Homes that have poor ventilation in general are particularly prone to humidity problems not just around windows, but in other areas, as well. The best solution in the long run is having your entire ventilation system checked and altered if necessary. Since that kind of operation can end up being a bit expensive, though, some homeowners find that putting a dehumidifier in areas that are particularly problematic makes a noticeable difference. In homes with forced air heating systems, you may be able to add a dehumidifier that kicks in whenever the heat comes on.

Storm window condensation can also be caused by a couple very minor maintenance issues. Storm window frames are manufactured with small holes that are meant to let moist air escape. Over time, these holes can get clogged. Clearing these holes will rekindle the proper air flow, and may solve your condensation problems. The main window, especially if it is older, may also be playing a role in excessive condensation. Gaps around window frames and loose panes of glass should be repaired to stop condensation and help maintain the integrity of the prime window.

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Improper Storm Window Installation

When installation is done well, it is a far less expensive (and sometimes more effective) operation than window replacement. When it is done improperly, however, many of the benefits of having storm windows are lost. Though it isn’t the most involved process in the home improvement world, if you want to do the job yourself, make sure that you follow the guidelines given by the manufacturer. Though installing storm windows does make a great do-it-yourself project, if your experience in such matters is a little on the light side, you should definitely consider the fast, efficient, and not as expensive as you might think option of professional installation.


  1. Carol R. Walton, September 14:

    Most important in storm installation is making an airtight seal on the storm, so that the area between the storm and the existing window is still air. The still air actually does the insulating.

    Be generous with the caulk. For ease of installation I pre-caulked the inside top of the storm when I installed them. Then I only needed to caulk the sides and bottom of the existing window placement area.

    My old house had 66 windows. After I determined which windows never needed to be opened, I put single pane storms on the outside which I made myself, or (for looks) inexpensive double hung commercially available storms.

    For more sunlight, skip putting the screen in if the window is never going to be opened. I never went up the ladder without all the tools I would need to do a complete installation.

    On windows that would need to be open for summer ventilation I installed only the storms that had self storing screens or in a few rare cases insider storms. Once again, these storms need to be well caulked in, so that when the storm part is lowered in winter there is a complete seal and still air. On the insider storms do not caulk, since they will need to be removed to open windows in summer.

    I would recommend professional installation for very big windows. Installing second floor windows is not for days with any wind. The storm can act as a sail.

    Getting existing windows clean before permanent installation is important since there will not be any opportunity to clean them after installation.

    I had very good luck with my storm windows. Before I put storms in, I had mayor ice buildup on the inside of windows. I had no ice buildup after the storms were installed. There was considerable difference in both heating costs and comfort after all the storms were installed. Definitely worth doing. I also blew insulation into my walls, resulting in a very comfortable house.

  2. Richard payne, January 31:

    Good info, thanks. I have a house built in 1984 and the storms in master bedroom are the storms that fog up on the inside the. Being retire and on social security I will try and take your suggestion of recalling the frames. I would like to know, if I plug the little holes in the storms will that help? Thank you.

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