The first week of February 2023 has been extremely cold in Ottawa, with the wind chill making it feel colder than -42.

With temperatures this low, more and more homeowners started seeing condensation and/or ice build up on the inside of their windows. Naturally, owners started wondering if this was normal at all.

We have prepared a short guide to address these concerns. Hope you enjoy the article below!

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First of all, is it normal to see condensation on windows?

Up to 1″ of condensate on all sides of the window is considered normal, especially if the outside temperature is below -20. If your windows are getting completely frosted over, it might be a sign of a bigger problem.

What Causes Condensation on the Inside of Windows?

Superficial condensation occurs when the surface temperature of a solid (glass, sash, frame) is lower than the dew point of the humid air in its immediate vicinity (Source: NRCAN)

In simple words: when warm & humid air meets a cold solid surface, condensation occurs. In case with window condensation, humid air from inside of your home meets the cold glass, and you see condensation on your windows.

How to Get Rid of Condensation Inside Windows?

While completely eliminating condensation might be hard to achieve, there are ways to control it. First, condensation can be decreased or eliminated by raising the inside surface temperature and, second, it can be changed by adjusting the relative humidity of the indoor air (Source: ibid)

How to Prevent/Reduce Condensation

Reducing or eliminating condensation often means using several complementary techniques.

These techniques concern the window itself, the method of installation, the interior window accessories (curtains, blinds, and valances), the arrangement of heat sources (hot air registers, baseboard heating, convection heaters) and the relative humidity of the indoor air.

The overall condensation resistance of a window depends on each of these factors (Source: ibid).

For the purpose of this article, we will focus exclusive on factors that are within homeowners’ control, i.e. relative air humidity and air flow.

Unimpeded Air Flow

To maintain the condensation resistance of the window, interior window accessories such as curtains, blinds and valances must not inhibit or impede the movement of air at the surface of the window.

Any restriction of air movement will reduce the condensation resistance and thus increase “sweating” on the window (Source: ibid)

In simple words: lift up the blinds by at least 2 inches to allow for air to flow freely and ventilate the window. Remove window blinds, curtains, or in general anything that obstructs the flow of air.

Arrange Your Heat Sources Correctly

Although energy-efficient windows are now available, the heat loss through them is still greater than through the adjacent walls.

This is why windows with heat sources located below them are less prone to condensation. When the heating system is in operation, the air temperature will be higher in the vicinity of the window than in the centre of the room, resulting in increased condensation resistance.

Care must nevertheless be taken to ensure that the hot air from the registers does not flow directly onto the interior surface of the glass, as this could give rise to thermal stress problems in the glazed unit that could cause the glass to break (Source: ibid)

In simple words: If you have a heat source that blows hot air directly onto the window (such as additional heaters), position this heat source away from the window or else the window might crack. Ceiling fans usually help air circulation and you might want to keep them on for a better air exchange.

Control the Relative Humidity of Indoor Air

The concept is very simple: the less humid the air inside is, the less water will condense on the windows.

This, however, is often easier said than done: living habits and the production of humidity in the house (showers, baths, cooking activities, plants, etc.) remain unchanged, and there is a significant reduction in the rate of air exchange, the resulting relative humidity at certain times during the winter may become excessive and cause condensation on the inside surface of new windows.

Reducing the amount of humidity in the house may enable you to limit or eliminate the problems caused by humidity.

How to Reduce Relative Humidity of Air in the House

• If your heating system is fitted with a humidifier, or if you use portable humidifiers, disconnect them.

• Avoid hanging laundry inside to dry, and make sure that the exhaust from the clothes dryer is vented outside.

• If you have a crawl space under your house, cover the beaten earth with 0.15 mm (6 mil) polyethylene. The crawl space may have to be ventilated during the summer.

• Make sure that your basement is well drained and protected against excess moisture. Also, make sure that gutters and the slope of the land around the house drain water away from the house.

• Try not to produce too much humidity. Plants, laundry, showers and cooking without lids are major sources of water vapour.

• Avoid drying firewood in the house. A cord of wood can release more than 270 litres (60 gallons) of water.

Indoor Relative Humidity Levels to Prevent Condensation

Outside Air Temp (°C)Max Indoor Relative Humidity at 20 °C
-30°C or below15%
-30°C to -24°C20%
-24°C to -18°C25%
-18°C to -12°C35%
-12°C to -0°C40%

Lowering relative humidity in your home should have limits, however. If it gets too low, air will get too dry, which will significantly reduce the comfort of your home, causing itchy eyes, scratchy throat, and dried-out mucus membranes.

The main takeaway therefore is to find a good balance between the comfort in your home and an acceptable level of condensation on the windows. If temperature drops are temporary, you might want to adjust relative humidity inside of your home, but it has to be reasonable.

My Windows Didn’t Pass the Test of Cold, What Do I Do?

Identify the root cause of such low performance. It could be that the window itself is decent, but it has not been installed properly. If it’s the case, you can get just have the window properly re-sealed/re-foamed and you should be good.

If, however, the window is too old, or the quality is unacceptably low, it might be the time to replace it, and we would be happy to help!

Give us a call or submit a form on this page to request a free quote. Check out the promotions section of our website, you might be able to buy a top-of-the-line triple glazed windows for the price of the double glazed ones, receive a government rebate and get an additional discount from Buildmart!

The selection and purchase of vinyl windows should be approached responsibly as these materials will be part of your home for decades. To avoid disappointment when winter arrives, it’s important to seek help from industry specialists. Buildmart Windows & Doors is always ready to provide professional consultation. However, if you have decided to select windows yourself, the following tips should be considered. High quality windows must guarantee:

Ideally, the window should also provide an elegant new look to your home. A carefully selected color, shape, and style will all contribute to making your home more comfortable and esthetically pleasing.

Criteria for choosing vinyl windows

Criteria for choosing vinyl windows

To choose high-quality vinyl windows, there are many aspects to consider from the insulating properties of the glass to the stylish design. It’s also important to properly measure and install the windows. You can get a rough estimate of measurements yourself, but our experts will double-check them before installation. At Buildmart Windows & Doors all measurements are taken for free, so you need not worry about costs and the work associated with this.

When selecting a vinyl window, the following features should be considered:

Window type

Window type

There exist two windows types: stationary and opening windows. The first type of windows is fixed. The windows do not open, have no handles or additional mechanisms. The opening windows are mobile and can be open or closed. Often, customers will select a combination of both window types for their home.



Vinyl windows are simple and easy to use, and their main features include a wide range of types and shapes. For example, you can choose slider windows that move easily without taking up space. Or opt for an awning window to air the room even during a rainy day. It’s important to determine which functions you expect from the windows and make your choice accordingly.

Insulating glass unit

Insulating glass unit

When it comes to insulating glass units the following criteria are important:

The number of chambers in a double-glazed window is important. The more chambers you have, the more soundproof and insulating the window will be. The best option for cold weather protection is triple glazed windows.

The second important parameter that will keep your home warm is the energy efficient glass. Energy efficient windows or energy star windows have a thin spray with a metal alloy, which reflects the heat from the window into the room and at the same time allows the daylight to pass through. Despite the spray, the glass remains transparent.

As for the inert gases, they are used to fill the chambers of a glass unit. Windows that use inert gases will ensure the house retains heat more efficiently. We recommend choosing the LOW-E Argon type which in turn ensures your heating costs will be reduced significantly.

Durability and warranty

Durability and warranty

A new window should serve for decades; a vinyl window will do just that. Vinyl is a sturdy and weather-resistant material that can withstand chips and cracks. It can easily endure Canadian climatic conditions. Ideally, it is best to buy windows with a guarantee, so that you can use them worry free.



Finally, it’s important to consider the aesthetic appearance of your windows. Buildmart Windows and Doors offers the widest range of window products and options. We offer black windows, colored windows, and painted windows. With them, your house will have a unique look that will make it cozy and attractive.

Reasons to replace windows

Reasons to replace windows

Best vinyl windows in Ottawa

Best vinyl windows in Ottawa

Buildmart Windows & Doors always considers the above criteria and chooses an particular approach to each order. We are ready to take measurements for free, provide advice and calculate the cost of the future installation of a vinyl window.

In addition to the eight standard types of windows we offer, our company has custom shape windows. Custom-shaped right-angled or bow windows are a perfect choice to compliment the character of your home. With such a large product assortment, we know that we’ll be able to meet the demands of every customer. Send us a message or come to our offices personally, Buildmart Windows & Doors will help you choose the best quality windows in Ottawa and the surrounding areas.

An entry door should perform multiple functions at once. It must protect one’s home from invasions, as well as have good thermal and noise insulation. That is why the choice and installation of your home doors must be made carefully.

Over the years, we’ve noticed clients chose an entry door based solely on its appearance without considering other properties. We also notice clients opting for the cheapest option and risk getting a “cardboard” like door that can deform or swell from the weather. To avoid these situations, Buildmart Windows & Doors will help you determine what quality doors and trim are right for you.

Characteristics to consider when choosing an entry door

Characteristics to consider when choosing an entry door

The most popular options are either classic or steel entry doors.

Classic doors are a versatile option that will suit any house interior. They come in a variety of material options, often made from solid wood with finger joints, solid wood veneer composite, or from a variety of wood species. The classic doors are easy to maintain, they are durable, which makes them a pleasant aspect to your home. You can also include fittings, sashes, and decorative glass to these doors. The classic version is suitable for those who want to independently choose all the components of the door and its appearance.

A good and reliable steel door should be selected when considering the following criteria:

The first thing you should consider is the intended use of the door. The front door should be not only sturdy, but also resistant to weather conditions. For apartment entry doors, the insulation from the penetration of odors and noise is important.

On top of this, you also must know the exact location of the door in your home. So, if you choose a garden door, you can select unique garden doors or patio doors. With these types of doors, the aesthetic appearance is more important, and the protection aspect is not as high of a priority.

The street door on the other hand, must be sturdy and tough.

In this case, we have two options in our store:

Best doors in Ottawa

Best doors in Ottawa

Buildmart Windows & Doors specializes in the supply and installation of a wide variety of doors for your home and garden. We are always attentive to the satisfaction of our customers, therefore helping you select the best option with a good price and the best quality. We also want to satisfy any aesthetic needs you may have as our doors look great with any home decoration. Our catalogue contains an incredibly wide assortment of various doors. You will definitely find what you are looking for at Buildmart Windows & Doors.