top of page

Why is there condensation on my windows?

Window condensation is a humidity issue. We understand that window condensation can be very frustrating and sometimes a daunting challenge to mitigate particularly during our cold “Winterpeg” seasons. While there is sometimes very little that can be done structurally or mechanically, we hope to provide you with information to better understand the problem.

condensation on windows

Each person and regular activity in your home adds more humidity into the air. To show you just how much moisture is added to the air inside your home, here is a chart that itemizes most common activities.

Type of Usage

Moisture Source

Liters/Gallons Added Per Week to Interior Air in your home


Occupants (4)

30-40 (7-9)

Showers (8 per week total)

18-29 (3-5)

Drying Clothes

12 (3)

Cooking (Steam)

9 (2)

Refrigerator (frost free)

9 (2)

Dishwashing (sink)

3 (.7)

Laundry (per load)

2 (.4)


Summer rain (open windows)

40 (9)

Damp Basement or Crawlspace*

10-25 (2-7)

Damp Basement or Crawlspace*

10-25 (2-7)

The ideal humidity in the home is about 35%. During the coldest days of winter, the humidity may need to be dropped down temporarily as low as 15-20% when condensation on windows becomes an issue. Once the weather moderates, the humidity levels should be increased to prevent permanent damage to the floors, cabinets and musical instruments.


So how do you know for sure what the humidity level is in your home? A $20. Hygrometer available at most box stores will monitor the humidity level and can help you determine what area in the home is generating the most humidity.

New homes have a naturally higher humidity level because the components that were used to build the home are still curing, making it difficult to maintain a 35% humidity level. By the second or third year, much of the window condensation/high humidity levels will be reduced.

Over the short term, here are some steps you can take that may help to ease the high humidity levels in your home. 

cooking moisture

  • A new home will typically expel 500 to 600 gallons of water in the first year and a half, so it is difficult to reduce condensation during this time.

  • It is normal to have about 1″ of moisture on a sealed window unit in the middle of winter.

  • Sliding or dual pane windows will typically have more condensation on them compared to a high efficient triple pane window.

  • Exhausting air is the most effective mechanical means to remove moisture from your home. Bathroom or range hood fans remove moisture directly at the source and by far provide the best results when connected to a timer that will allow for an extended exhaust cycle. We suggest running exhaust fans at least an extra 15 minutes after their normal use.

  • Kitchen exhaust fans must be vented directly outdoors to effectively remove the humidity produced while cooking.

  • Keep the bathroom door closed during use and consider running the exhaust fan up to an hour after taking a bath.

  • An HRV when properly used can also help to reduce humidity. It is however very important to know the actual outdoor humidity on any given day since the incoming fresh air may actually hold a higher level of humidity that what is in your home. Ensure the filter inside the HRV unit is clean to allow proper air movement.

  • Open a door or window for short periods to allow moisture to escape. 

  • Go outside and be sure the “fresh air intake” screen is not frosted over. Check the furnace and HWT pipes to be sure there is no snow accumulation near the pipes and check the screens inside the intake to be sure these have not frosted over.  If any of the screens are completely frosted over, there will be no fresh air getting into your home and the furnace and HWT may shut down completely. If they are partly frosted over, there may be increased humidity in the home. 

  • Clothes dryers must be vented to the outside. Hanging up wet clothes to dry inside your home can add significant moisture to your home.

  • Free air circulation is important. Do not cover hot or cold air registers with furniture or appliances. Leave bedroom and bathroom doors open.

  • Wipe up any tracked-in snow before it melts and evaporates.

  • Wet floors from mopping can add large amounts of moisture. Run exhaust fans (bathroom and kitchens) while floors are wet. Avoid washing floors on extremely cold days.

  • Drapes and blinds should be left open during the daytime. At night, raise blinds at least 4″ up (preferably 6-8″) off the frame to allow air to flow against the glass.

Tradesman Mechanical can provide you with solutions to your humidity concerns.

Call or text us today for a complimentary consultation.

204-888-2020 We are:

Recent Posts

See All


Komentavimas išjungtas.
bottom of page