Call Now 1.800.265.1914

Why is There Condensation on the Inside of My Windows?

February 15, 2018

Do you notice condensation on the inside of your window during the winter? If so, it’s not an uncommon occurrence. Window condensation in winter is triggered by a number of dynamics. To begin with, homes are quite “sealed” today and outside ventilation is usually lacking. As a result, indoor air tends to hold high (and often damaging) levels of moisture levels in winter.

If you’re concerned about the amount of condensation on the inside of your window, there are remedies available. The aim is to remedy the situation before there’s any damage – like ruined window frames, or worse still, mold growth around the sills. Indeed, window condensation may also point to poor indoor air quality – again related to the lack of proper ventilation throughout.

How to fix condensation on the inside of your window?

When there’s too much condensation on the inside of your window, it’s because warm air inside the house is condensing on a cold window. In some situations, condensation can form in between the windowpanes. Here, the potential for damage is greater, and a proper fix even more urgent.

Turning down the humidifier

When you notice condensation on the inside of your window (or in the bathroom), one of the most basic solutions is to lower the humidity setting on the humidifier attached to the furnace.

The humidifier unit will then release less moisture and window condensation will be reduced.

Better indoor air circulation

Improving the air circulation inside the home will also reduce high levels of condensation. With the furnace, its possible to have the fan running consistently, thus creating air circulation. For some, operating a ceiling fan in the winter can also be helpful (fans should rotate clockwise).

Improved weather-stripping

By improving the weather-stripping around windows, warm indoor air is blocked from escaping in the winter. This happens to be one of the easiest and most effective remedies for reducing window condensation. Weather-stripping will also make your home far more energy efficient.

Retrofit the storm windows

Short of replacing windows, there’s an innovative retrofit now available from MAGNETITE. The patented frame assembly is retrofitted into an existing window, thus providing a snug fit that locks into place. The retrofitted window becomes fully airtight and insulated at the same time.

Checking for humidity issues

In winter, humidity levels should be around 30% in order to prevent window condensation. If an exterior window shows unusually high condensation, it’s a sure sign that indoor humidity levels are too high, relative to the indoor temperature. Very high levels can be professionally measured.

Bathroom and kitchen fans

Proper use of bathroom and kitchen fans is essential in controlling indoor humidity. Showers and cooking actually releases a lot of air moisture, and a proper fan system will allow that moisture to escape. Exhaust fans, properly vented to the outside, are critical in reducing indoor air moisture.

Fixing the vapour barrier

When indoor condensation is a result of mechanical issues like air leakage or poor insulation, a retrofitted vapour barrier may be the answer. Vapour barriers are specifically designed to stop air moisture from collecting. Here, professional advice and installation is highly recommended.

When condensation on the inside of your window becomes untenable, there are a host of possible remedies. Some are “low-tech” and personally manageable, while others require the expertise of a professional. Whatever the case, it’s worth doing right the first time around. 

Western Ontario

935 Keyes Drive
Woodstock, Ontario
Canada N4V 1C3

Phone: 1-800-265-1914

Fax: (519) 539-7946
TOLL FREE: 1-800-265-1914

Southwestern Ontario

7035 Industrial Drive
Comber, Ontario
Canada N0P 1J0

TOLL FREE: 1-800-265-1914

Muskoka, Haliburton, Northern Ontario

1027 Elwell Park Road
Gravenhurst, Ontario
Canada P1P 1R1

TOLL FREE: 1-800-265-1914

Central Ontario

29 Ferndale Industrial Drive
Barrie, Ontario
Canada L4N 9V5

TOLL FREE: 1-800-265-1914

GTA East

103 North Port Road
Port Perry, Ontario
Canada L9L 1B2

TOLL FREE: 1-800-265-1914

GTA & South Central Ontario

450 Industrial Dr,
Toronto (Milton), Ontario
Canada L9T 5A6

TOLL FREE: 1-800-265-1914

Eastern Ontario

1035 Moodie Dr #1,
Nepean, ON
K2R 1H4

TOLL FREE: 1-800-265-1914


259 Campbell Street
Sarnia Ontario
Canada, N7T 2H3

TOLL FREE: 1-800-265-1914

Niagara Region

6260 Don Murie St
Niagara Falls, ON
L2G 0B4

TOLL FREE: 1-800-265-1914


Great Northern Insulation - Better Business Bureau Profile.


Best of 2017

From reputation to responsiveness, HomeStars consistently ranks Great Northern Insulation at better than 95% for customer satisfaction. Thanks to everyone for the great ratings! 

HomeStars 2018

Best of 2018

For the second year in a row, HomeStars consistently ranks Great Northern Insulation at better than 95% for customer satisfaction. Thank you again to everyone!

Homestars Best of 2019 Award

Best of 2019

For the third year in a row, HomeStars ranked Great Northern Insulation at better than 95% for customer satisfaction.

Homestars Best of 2020 Award

Best of 2020

For four years now, HomeStars has ranked Great Northern Insulation at better than 95% for customer satisfaction.

Homestars Best of 2021 Award

Best of 2021

HomeStars has ranked Great Northern Insulation as a company that goes above and beyond in every aspect of business for the year of 2021.

Homestars Best of 2022 Award

Best of 2022

HomeStars has ranked Great Northern Insulation as a company that goes above and beyond in every aspect of business for the year of 2022.


GNI is the Authorized & Trusted Insulation and Air Sealing Installer for Lowe’s

Enenrgy Savers

Energy Saving

Energy saving and energy efficiency is easier than one might think. Great Northern Insulation helps to identify performance issues, while taking advantage of improvement opportunities.

100% Canadian

100% Canadian

Great Northern Insulation is recognized as Canada's largest full-service insulation contractor. GNI is 100% Canadian owned, proudly serving Ontario customers since 1980.

Foam Masters

Do it right the first time
- with foam mastersTM

WALLTITE® ECO™ is a high-performance system, professionally installed by certified and approved specialists. Its C.C.M.C. approved (Canadian Construction Materials Centre) - with product quality guaranteed - and with installation by highly trained experts with the technical know-how to do the job right, the first time.

Insulthane Extreme

Insulthane® Extreme

For the ultimate in high performance spray foam insulation, Insulthane® Extreme is the professional choice for residential, commercial, and industrial application. With improved thermal performance over other products, Insulthane® Extreme has an exceptionally low Global Warming Potential (GWP). Considered environmentally friendly, this next generation spray foam insulation is non-ozone depleting, and exceeds specifications of other HFC product alternatives.


3MTM products.
Quality + Performance = Savings

3MTM energy-saving products are designed to keep warm air in, and cold air out, while keeping energy bills down. Products optimize energy efficiency in buildings and homes; improve indoor environment for occupants; and effect the reduction of seasonal energy costs. 3M products are authorized for LEED credits (Leadership in Energy/Environmental Design).


Baeumler ApprovedTM
Professional, Certified and Insured

Baeumler ApprovedTM gives you peace of mind when connecting with contractors, trades and home service providers. All Baeumler Approved members have demonstrated high quality work for customers and other trade professionals. Members must also have Workers Compensation, liability insurance of at least $1,000,000 and prove professional certification.

Holmes and Holmes

Holmes and Holmes


Mike Holmes and his son Mike Jr. (MJ) convert MJ’s bachelor bungalow into a two-storey home for MJ and his girlfriend Lisa. Choosing the newest materials and build techniques, the father and son team follow Mike’s famous motto – “Make it right.” The show can be watched on HGTV and DIY Network.


Enbridge Incentives

The Energy Conservation Program provides incentives of up to $1,600 to customers who achieve energy efficiency and fuel savings – and Great Northern Insulation can pave the way.


Great Northern Insulation proudly abides by a renovation-specific Code of Conduct set by RenoMark™.


We are Verified & Bonded by eRenovate. When you choose to proceed with our services through their platform, you receive the gaurantees set forth through their program.

As Seen on Love It or List It

The GNI crew have been featured installing insulation on Love It or List It - have you seen our logo in an episode?

Please, enter a valid value

Incorrect values!