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How and why to add an egress window to your basement

You want to have your basement legally designated as a living space, but to do that, fire safety code requires that you have means of egress in specific areas. Fortunately, adding an egress window or door to an existing basement is a simple and relatively common project.

Our team at Lamont Bros. has worked with several Portland-area homeowners to help them turn their basement into liveable space. Oftentimes, part of this process involves adding a basement egress (or several) to meet safety standards. Although it may initially seem complicated, adding an egress can be easy if you have a good design plan.

This article will discuss several factors involved in adding a basement egress to your home. By the time you finish reading, you should be able to identify why your basement needs an egress, where in your home any egresses should go, and what the installation process looks like. Specifically, we’ll discuss:

What is a basement egress?

Most likely, you’ve heard the word “egress” associated closely with basements. However, an egress is by definition any opening through which you can exit a building. There can be egresses on any floor of a home. Most doors and windows larger than 5.7 square feet are considered egresses. 

However, because basements are underground, it takes more planning and labor to create an egress to a basement. This is why basement egresses are in a particular category of their own.

By law, a finished basement must have at least one egress for escape in case of a fire. The dimension requirements for a basement egress ensure that a person can easily escape through the opening. A firefighter should also be able to easily climb down into the basement if necessary. 

To meet construction code requirements, a basement egress must:

  • Have an opening of at least 5.7 square feet
  • Measure at least 20 inches wide and 24 inches tall
  • Open easily to the outside
  • Have a path to the outside clear of any obstructions
  • Be within 44 inches of the floor
Guide to egress window dimensions from the City of Portland.

Why does your basement need an egress?

Keep in mind – only finished basements need to have an egress. So why do people choose to add egresses to their basement? Oftentimes, it has to deal with home value. 

An unfinished basement is a basement that does not meet the requirements to be considered “legal living space.” You can still use an unfinished basement however you want to, but it doesn’t count as living space. This matters because unfinished basements don’t count towards your home’s official square footage.

In other words, let’s say you have a home with 2,500 square feet including a 30’x30’ unfinished basement. Legally, that basement would not count as living space, so your home’s legal square footage would be 1,600 square feet. 

As a general rule of thumb, a finished basement adds about 50-60% of the main floor’s value per square foot to the home. So, if a 1,600 square foot home is worth $545,000 without a finished basement, that’s $341 per square foot. At 60% of the main floor’s value, a 900-square-foot basement would be worth $204 per square foot and add $184,000 in value to the home.

What’s the difference between egress windows and doors?

Although egress windows are more common than egress doors, either one can be an effective choice depending on the needs of your basement. Here’s a breakdown of the differences between the two.

Egress Windows

In a basement, an egress window sits mostly underground. On the exterior side of the window is a vertical hole that extends from the bottom of the window up to ground-level height. 

It’s important to keep dirt, debris, and water from collecting in this hole, as those would create an obstacle in the case of an emergency. As a result, egress windows also have a rigid structure that holds the dirt back from the window, called an egress well

Unlike egress doors, egress windows are designed to be used only in emergencies. An egress window is most appropriate for basement bedrooms since they don’t usually need direct access to the outside. Egress windows also take up less ground space than egress doors, so they’re the preferred type of egress in space-restricted areas. 

Egress Doors

An egress door is much like an egress window, except that it is designed for more regular use as an entrance and exit. Instead of a well, egress doors usually have a staircase or ramp on the outside. In the case of a daylight basement, the egress door opens directly to the outside ground level.

Egress doors are great for saving interior space, both in the basement and the floor above. When there is an access point from the outside, it negates the need for an interior staircase, which takes up a lot of space that could otherwise be used as living space.

You’ll find egress doors most commonly used in basements that function as separate units from the main house, such as a basement ADU. Having its own door means residents can enter and exit without disturbing anyone else. An egress door works best in a living room or common area rather than a bedroom.

An egress door provides exterior access to a basement.

Designing and Installing a Basement Egress

Now that you understand what a basement egress is and what forms it can take, let’s look at how to add one to your home.

Deciding the number of egresses

The first thing you need to do is figure out how many egresses you’ll need in your basement. To qualify as a legal living space, a basement must have at least one egress. If you have a daylight basement, a door to the outside will suffice. If the basement is totally below grade, either an egress door or window should be installed.

Although a basement only requires one egress to be considered legal living space, bedrooms are a different story. Like square footage, adding bedrooms to your home is a great way to increase the home’s value. If you plan to designate any of the rooms in your basement as bedrooms, each bedroom must have its own egress, as well. So, if you plan to put three bedrooms in your basement, you’ll need to add three egresses.

In some cases, it’s best to add more egresses than is legally necessary. For example, if your basement is one large game room you could skate by with one egress on one wall of the basement. However, for safety reasons, you should consider adding more egresses than just the one. Remember, the larger the room, the further a person might have to travel to reach a single exit point. With multiple egresses, people can choose the nearest one in case of an emergency. 

A finished basement must have at least one egress window, including one for every designated bedroom.

Finding the right placement for an egress

Once you know how many egress points you’ll need in your basement, you’ll then need to figure out where they’ll go. When designing the placement for your egresses, there are a few factors to consider.

An important issue is to consider the location of the property lines and setbacks. An egress well cannot extend past a land setback which can affect what side of the home you can place a basement egress. Doors are more difficult to place in this situation since the stairwell extends out further than a window well would. 

Utilities such as gas lines, electrical cables, and sewer pipes can also get in the way. While it’s best to simply avoid putting an egress adjacent to a utility line, it is possible to move the utility if necessary.

Cantilevered bump-outs on the main floor can also be a challenge. These architectural features extend out past the home’s foundation. If you place an egress well below a bump-out, the well must extend past the edge of the bump-out so a person can escape without being trapped by the bump-out above. The same applies to decks and balconies, as well.

Also, consider the lighting in your basement. and try to place the egress in a place that receives a lot of light. The south side of the home receives the most sunlight throughout the year and is generally the best place for an egress. The east side receives sunlight in the morning, while the west side gets it in the evening. The north side of your home never receives direct sunlight.

Constructing a basement egress

Now that your design work is done, it’s time to build the egress. Installing an egress into an existing basement is much more difficult than building an egress into a new foundation. You’ll want the help of a professional contractor who has experience with modifying foundations.

The first step in the process is to excavate the exterior of the basement wall. If you live in a historic home, the foundation can present several challenges on its own due to the age of the concrete and the building practices of the time it was built. 

After excavation, the hole must be stabilized to prevent it from collapsing. For egress windows, the best option is to use an egress well, which holds the dirt in place and prevents the hole from filling in due to erosion. For an egress door, it’s best to use concrete, both to hold back the dirt and construct the staircase or ramp leading down to the basement.

Once the egress well is secured, then comes the difficult task of cutting through the concrete. This job requires specialized equipment and is a very delicate procedure. Cutting a hole in your foundation can compromise your home’s structural integrity if not done properly. And unless you want to order a custom-sized egress window or door, the hole will need to be carefully cut to specific dimensions to fit a standard size.

Then comes the process of installing the egress itself. Because it will be below ground level, a basement egress needs proper weatherproofing and installation. Otherwise, water can get into your home through the egress and cause rot or mold. Egress windows also come in different styles, with casement and sliding windows being the most popular. 

Does your basement project need a designer’s touch?

Now that you understand the process of installing a basement egress, take the next step! Check out our Basement Remodel Portfolio to learn more about the basement remodeling process and begin gathering ideas. You’ll be able to browse photos of other Portland area basement remodels and see what’s possible for your own home.

Keep in mind that a basement remodel is a technically complex project with lots of laws to follow. To make sure you get the final product you’re after, it’s best to work with a design team who has been through the process before. Click the button below to schedule a free design meeting with one of our professional designers. We’ll discuss the remodeling process with you and help you navigate the challenges of turning your current home into your dream home.