Sauna Windows – Can You Have Them? (Materials, Thickness, & Size)

If you are installing or building a sauna, you will face the ever-important question of whether to add windows or not. While some people find the idea of a window appealing, you might wonder whether it will affect the performance of your sauna.

While windows are not traditional in saunas, it is possible to install a sauna window if you want a view or natural light. The most important considerations when putting a window in a sauna are heat retention and efficiency, so smaller is better and it should not open. The window should be made of tempered glass with wood trim and fittings for best results.

Keep reading for more information on sauna windows and how to maximize your sauna’s efficiency while giving yourself a view of the outside world.

Can you have a window in a sauna?

You want a traditional sauna look and feel, but you also want to let in some natural light and be able to look out on nature or in your house while you relax. Can you have a window in a sauna?

It is possible to install a window in your sauna without compromising heat and energy efficiency. Choose a window made of wood (preferably cedar) and double-pane tempered glass as both are good insulators. The window should not open and should be relatively small – only about one square foot.

There are a few challenges to consider when you put a window in a sauna, but for some people, the benefits are worth the extra work.

Potential problems with sauna windows

While natural light is a big draw for including a window in your sauna, there are some major drawbacks to putting a hole in your carefully constructed hot box.

A poor-quality window in your sauna will cause issues with its performance:

  • Reduced temperature control
  • Cracked glass
  • Condensation obstructing the view

The main issue is that there is the potential for heat to escape or for cold air to seep in, causing you to use more energy to keep your sauna at the ideal temperature.

If you live in a very cold climate, the contrast between the sauna’s heat and the outdoor air may cause the glass to crack.

And finally, condensation may occur, defeating the purpose of having a window for a view in the first place.

Potential benefits of sauna windows

On the other hand, there are some great benefits to having a sauna window.

Sauna windows have several benefits including:

  • Natural light
  • Appearance of space
  • Views of nature
  • Ability to check-in

The natural light that streams in will make the atmosphere warm and inviting. Since saunas tend to be very small rooms, a window can help the area feel more spacious.

A window placed with a view of the outdoors can provide relaxing visual stimuli of nature, further enhancing your sauna experience. On the other hand, a window placed with an interior view, perhaps connecting to your changing area, can allow you to keep an eye on your home and let others look in before entering so you are not unnecessarily interrupted.

What kind of windows do you need for the sauna?

So you’ve decided to install a sauna window. Where do you go from here? What kind of windows do you need for the sauna?

You should install a small window using double-pane tempered glass and wood framing and fixtures. Windows that do not open are ideal for maintaining temperature, but if you need venting, you can install a window that opens.

Read on for more details on sauna window specifications.


The size of your sauna window will depend on your preferences and needs.

Smaller is better when it comes to maintaining the warm temperatures desired in a sauna. A good guideline to keep in mind is that more window area means more use of the heating element to keep the sauna hot.

Exterior windows facing outdoors should definitely be kept on the smaller side to help retain heat – generally about one square foot in area.


Typically, people install windows using either single- or double-pane tempered glass.

Either will work in a sauna, and they each have their advantages, but typically double-pane tempered glass is the material of choice.


Most of the windows in your home are made of regular glass, although tempered glass is typically used in and around doors.

Single-pane tempered glass is either 3/32” or 9/16” thick and is stronger than regular glass, and less expensive than the thicker double-pane tempered glass.

It is also less expensive to purchase than the thicker double-pane tempered glass. However, because it is less thick than double-pane, it loses heat more easily and provides less insulation, making it less than ideal for sauna conditions.  


Double-pane tempered glass, also known as insulated tempered glass, is the most frequently used material in sauna windows.

Double-pane glass is two pieces of single-pane glass sealed together with air in between. While it is more expensive than single-pane glass, it has superior insulating properties and will save you money in the long run by improving energy efficiency.


Most saunas themselves are built from cedar, because it is resistant to the effects of heat and humidity but also acts as a good insulator.

Your window trim and fixtures, in the same manner, should also be made of wood – cedar if possible – so that your windows do not become warped and inefficient.

You should also be sure to choose the right kind of glass for your windows.

Do you need special glass for a sauna?

The best glass for saunas is tempered glass, because it is more insulating than regular glass and helps keep heat in and cold out.

Tempered glass is more durable than regular glass, and it stands up to changes in temperature better and helps maintain the energy- and heat-efficiency of your sauna.

It also may reduce condensation on the window, keeping your view clear.

Should sauna windows be able to open?

Fixed windows, or windows that do not open, are ideal for maximum insulation and energy efficiency.

If a window can be opened, there is unlikely to be a perfect seal and there will probably be some loss of heat. However, some people prefer a window that can be opened instead of a traditional vent.

In this case, it is important to ensure that the window is fully closed while the sauna is in use to keep the ideal temperature.