Window Condensation in tiny homes

With temperatures below zero, we see people concerned about window defects because there is condensation on the glass.
That spurred me to write about condensation on glass. It matters little if they are Pella, Marvin, Jeld Wyn or Crestline windows.

Condensation facts you should know

Window condensation; where does it come from?

Today’s energy efficient homes and tiny houses are built more airtight than ever. But in addition to sealing in warmth and air conditioning, they also send to hold in too much moisture laden air.

If your home contains excessive moisture and it is cold outside, the 1st place you will see it is on your windows, and it makes little difference which brand name we discuss. They will all have condensation on the glass as the temperature drops. You may think this means that there is a problem or defect with the window, but it does not! In fact, the vast majority of window condensation problems are not the fault of faulty windows. The windows are just indicating that your home needs added ventilation to lower the moisture in the home.

Can condensation damage your windows?

Occasionally, beads of moisture o n your windows is not a problem.

For example, it is likely your bathroom mirror  and windows will steam up after a hot shower.  Or your kitchen window may fog up when you’re boiling food on the stove.but in both of these cases, the moisture clears in a few minutes.

However, if your windows are sweating at other times, or stay that for any length of time — you may have a problem!Window Condensation

Although the glass itself may not e affected, dropping condensation and excess moisture can not only damage your windows but potentially your entire home and tiny house.

  • Wood frames and sash can warp and become difficult to operate.
  • Paint can peel and other finishes become  mottled or stained.
  • Insulation can become damp, damaging ceilings and walls.
  • Exterior siding and finishes can become blistered and warped.
  • Interior surfaces can become breeding grounds for mold and mildew.

That’s why it is so important to take the steps to control and eliminate excess moisture!

Where does all the moisture come from?

In a word, everywhere.

  • In the kitchen, moisture is generated by cooking food, using the sink,, and running the dishwasher.
  • In the bathroom, from showers, hot tubs, toilets, and spas.
  • Washers and indoor-vented dryers contribute as well.
  • Basements and crawl spaces can channel dampness from the ground to our home.
  • Even breathing and perspiration adds moisture to the indoor air.

Collectively, a family of four can easily generate up to 18 gallons of water a week in the form of humidity inside your home.

How can you get rid of excessive moisture?

To lower your home’s humidity levels, you need to increase ventilation and decrease the sources of moisture.

  • Make sure you have good ventilation in high-humidity areas; bathrooms, the kitchen, laundry areas and in the basement
  • If you already have adequate exhaust fans and dehumidifiers in thesed areas, try running them for longer periods of time.
  • Take shorter showers and install water-restricting faucets –                                                                     you’ll lower the humidity and your energy bills as well.
  • Cook a little differently. Keep pots and pans covered to hold the moisture in. Use your your microwave instead of boiling on the stove. Slow cooking crock pots are extremely energy efficient and moisture efficient as well.
  • Check and reroute drainage away from your home to minimize the moisture in and around your basement and crawl space.

How much humidity amount?

You’ve probably heard that your home will feel warmer in winter if the humidity is higher. That’s true, and yet why many people use humidifiers to counteract dry static-filled air during the heating season.

Is the right older homes excessive moisture usually us a problem because the structure breathes through unsealed cracks and crannies in the construction, creating a regular exchange of outdoor and indoor air. That’s why it is often a struggle to keep enough moisture inside older homes.

But with today’s modern building techniques, homes are much tighter and energy efficient. As a result, newer homes don’t usually need a way to add moisture – they’re more likely to have trouble getting rid of it.

So how much humidity is enough to keep us comfortable without dampening our surroundings? Refer to the chart for temperature and humidity levels that are generally recommended.

Not sure what the humidity level is inside your home or tiny house? Ask a HVAC (heating ventilating and air conditioning) contractor to measure it for you.

Suggested Humidity Levels for Maximum indoor comfort

Indoor Air Temperature

Outdoor air temperature

Recommended Max Humidity


Below -20F



-20F to -10F



-10F to 0F



0F to 10F



10F to 20F



20F to 40F



Source; University of Minnesota Engineering and Experiment Station

What else can you do to lower excessive indoor moisture levels?

The basic principle of reducing window condensation  is simple. When there’s too much condensation on your windows it means the humidity is too high in your home or tiny house for the current temperature outside.

Here are some additional actions that may help reduce humidity levels:

  • Open your windows occasionally to vent excessive moisture
  • If the condensation is on the storm window, open periodically to vent excess moisture
  • Open drapes and blinds to allow warm house air to circulate against the window
  • Turn off your furnace humidifier mor other home humidifiers
  • Make sure your humidifiers are working properly and are well drained
  • Be sure that louvers in the attic or basement crawl space are open and are of adequate size
  • Run Ventilating fans in the bathroom and kitchen longer in the kitchen and more often
  • Air out your house by opening a door or window for a few minutes after the bathroom, kitchen or laundry has steamed up
  • Install an air exchanger to constantly exchange the inside and outside air such as a Whisper Quiet Panasonic air exchanger or a Bal Port air exchanger.
  • Lower the indoor air temperature and dress warmer, add a blanket to the bed, wear a sweater. The cooler the inside temp is the less moisture the air can absorb.

Is there any condensation that’s temporary?

There are two causes of temporary window condensation, and they normally disappear after a few weeks.

First, there is moisture that comes from new construction or remodeling. There’s moisture in new wood, plaster, and other building materials. For instance, I recently installed reclaimed barnwood siding and power washed the siding to clean it. That moisture would also be driven into the wood and it would take time to dry out. When the heating season starts, this moisture gradually flows into the air of the home. After a few weeks or a month or two, or a heating season, that moisture would disappear.

Second, this same type of moisture can accumulate in milder form at the beginning of each heating season. During the summer, your home and tiny house absorbs moisture. After a few weeks, your home would dry out and you;ll have less trouble with window condensation.

What is there’s condensation between the pieces of glass in an insulating window?

As building experts often point out, windows should not be blamed for condensation. They are merely an indicator of too much moisture in the air.

In an unlikely event you see condensation between the panes of glass in an insulating window, contact the window contractor or manufacturer or dealer directly who sold the windows. Moisture between the panes means that the seals on the glass has failed. It is a very rare occurrence, but one that is usually covered for 10-20 years under the manufacturers limited warranty.


Some of the information in this article was derived from the following sources:

  • Moisture and Home Energy Conservation US Dept of Energy
  • Washington Energy Extension Service Technote
  • University of Illinois and Urbana-Champaign – Small Homes Council – Building Research Council
  • Better Business Bureau of Philadelphia, Condensation on Windows
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