Egress Window: Requirements, Types and Whether You Need One

An egress window is a window large enough to climb out of in an emergency, and in a basement it is usually the thing standing between a finished room and a legal bedroom. Bob Vila puts the function plainly: egress windows not only bring light to dark basement spaces, but they are also a vital safety feature. A basement egress window is therefore a code item first and a lighting improvement second.

Last reviewed and updated: October 9, 2026. Written by Jeremy Jarvis.

What makes a window an egress window

This Old House describes it simply: an egress window resembles a regular window but opens fully to serve as a secondary emergency exit.

Bob Vila makes the same distinction. Egress windows look like any other window, but they must be large enough to fit through if someone has to climb out of one during an emergency.

So the defining property is the clear opening when the window is fully open, not the size of the glass or the frame. That distinction causes more failed inspections than anything else in this subject, because a large window with a small opening does not qualify.

When an egress window is required

The trigger is use rather than finish level, which catches people out when converting a basement gradually.

Bob Vila states that homeowners who use their basements as bedrooms, offices, TV rooms, or other living spaces are required to install egress windows, and that any room that residents live in or use frequently needs an egress window, or a window large enough that it can be used as an escape during an emergency.

This Old House frames it from the code side, noting that your area’s building codes may require you to install an egress window in your finished basement or any livable space below the fourth floor.

Requirements are set locally, they vary by jurisdiction, and they change. Confirm with your building department before designing anything, because the answer determines the whole project rather than one detail of it.

The dimensions that are usually specified

This Old House Magazine publishes the code minimums as three requirements that apply together.

The interaction between them is the part worth understanding. An opening at exactly the minimum width and the minimum height falls short of the 5.7 square feet This Old House Magazine specifies, so it fails the area test while passing the other two.

Consequently at least one dimension has to exceed its minimum comfortably. In practice this is why basement egress windows end up noticeably larger than people expect when they first read the width and height figures.

These are the figures as published, and local code governs. Verify them for your jurisdiction before ordering a window.

Window types that work

This Old House notes that egress windows come in multiple window styles, but that simple casement and transom windows are the most common types.

• Casement. Hinged at the side and swings fully open, so almost the whole frame becomes clear opening. The most efficient type for meeting the area requirement in a limited width.
• Sliding. Only half the unit opens, so the window has to be roughly twice the required area. Needs a wide opening in the wall.
• Single or double hung. Similar limitation, since only one sash moves.
• In-swing. Opens inward, which suits a tight window well but uses space inside the room.
• Transom. Noted by This Old House as common, typically where the available height is limited.

Casement units are popular for a structural reason as well as a geometric one. A smaller opening cut into a foundation wall is cheaper and less disruptive than a wide one, and a casement reaches the required area in the narrowest opening.

The window well is part of the system

Below grade, the window needs a well: an excavated area held back by a retaining structure so the window can open and someone can climb out.

The well has its own requirements in most jurisdictions. These cover how far it projects from the wall, its width, and whether a ladder or steps are needed when it is deep. A ladder that intrudes into the required clear opening can invalidate it, which is a detail suppliers do not always flag.

Covers matter too. A cover keeps out rain, leaves and debris, and in a deep well it also addresses the risk of someone falling in. Any cover has to be openable from inside the well without tools or special knowledge. A secured cover over an escape route defeats the purpose of the window.

Drainage is where these go wrong

A window well is a hole in the ground next to your foundation, which makes it a water feature unless it is drained.

Bob Vila is direct about the risk: to ensure that windows are installed properly and avoid future water damage and mold growth, it is a good idea to have a professional install egress windows. Water damage and mold are named outcomes, not hypothetical ones.

A well should have a drain at its base, bedded in stone rather than sitting in soil, typically connecting to the footing drain or a dedicated run. The ground around the well should fall away from it. The well should also extend far enough above grade that surface water cannot run straight in over the top.

Where a basement already has water problems, deal with those before cutting a new opening. Our water after rain guide covers diagnosis, and our waterproofing guide the remedies.

Where the basement egress window can go

Position is decided before size, and the constraints are more limiting than most plans assume.

Start outside rather than inside. The window needs a well, and the well needs ground to sit in, so anything immediately outside that wall matters: a driveway, a patio, a path, an air conditioning unit, a boundary fence, a mature tree or a neighbouring building can each rule out an elevation entirely.

Then look at the wall itself. Services running inside it, a beam bearing above, an adjoining chimney breast or a run of ductwork can all make one section far more expensive to open than another a few feet away.

Inside, think about the room the window serves. The requirement attaches to the room being used as living space, so the window has to be in that room rather than in the corridor outside it. That single point frequently reshapes a floor plan, because the convenient wall for a window is not always the wall of the bedroom.

Finally, consider what will sit in front of it once the room is furnished. An escape route behind a bed or a wardrobe satisfies an inspector on the day and nobody thereafter, so plan the furniture layout while the window position is still a drawing.

What installation involves

The sequence explains why this costs what it does, and why it is not a weekend job.

1. Confirm the requirement and obtain a permit where one is needed.
2. Locate services, since excavation happens right against the house.
3. Excavate outside to the depth of the proposed well.
4. Cut the opening in the foundation wall, with temporary support where required.
5. Form and finish the opening, and fit a header if the design calls for one.
6. Install the window, flashed and sealed against water.
7. Fit the window well, fixed to the foundation.
8. Install the well drain and bed it in stone.
9. Backfill, reinstate the ground, and finish inside.

Step four is the one that rules out DIY. Cutting a structural opening in a loaded foundation wall is engineering work, and getting it wrong is not recoverable with sealant.

How long it takes

This Old House gives a figure from its own survey: over 40% of its November 2025 respondents who purchased egress windows nationwide reported that installation took between two and three days to complete.

That matches the sequence above. Excavation and cutting occupy the first day, the window and well the second, and backfilling, reinstatement and interior finishing the third.

Weather affects it, since the excavation is open while the work proceeds. Scheduling in a dry season is worth doing where you have the choice.

What it costs, in brief

Two sources agree closely. Bob Vila, citing Angi, gives a typical range of $2,621 to $5,662 with a national average of $4,129. This Old House gives $2,718 to $5,878 with a national average of $4,216.

Bob Vila also breaks the average down. It gives materials between $100 and $700 per window, and $100 to $250 per window for installation. It then adds the item that dominates a basement job: if it is necessary to cut through a wall or excavate to install egress windows, Bob Vila says costs may be about $1,500 to $3,000 per window.

That last figure is the real story of a below-grade installation, and our egress window cost guide works through it in detail.

Permits and inspection

This is a permitted alteration in most jurisdictions, and for good reason: it changes a structural wall and it creates a life safety provision.

Bob Vila lists labor and permits among the cost factors, so expect the fee in a quote. More importantly, expect an inspection, and expect the inspector to measure the clear opening rather than taking the product literature at face value.

Unpermitted work surfaces at sale. A basement bedroom created without a compliant egress window and without a permit is likely to be challenged by a buyer’s inspector, and the remedy at that point is the full job under time pressure.

Living with one afterwards

An egress window is a safety provision, which means it needs to keep working rather than simply having been installed.

Keep the well clear. Leaves, soil and windblown debris accumulate quickly, and a well half full of material is both a drainage problem and a smaller escape route than the one that was signed off. Clearing it twice a year is enough in most gardens.

Check the drain actually drains. Pour a bucket of water into the well and watch it go. If it stands, the drain is blocked or silted, and the next heavy rain will put that water against your foundation and your new window.

Open the window periodically. Casement hardware seizes if it is never used, and a window that will not open fully is not providing the clear opening the whole project was about. Twice a year, with the smoke alarm check, is a reasonable rhythm.

Make sure everyone in the house knows it is there and how it opens, including children who sleep in that room. An escape route nobody has practised is a plan rather than a provision.

Mistakes that cause failures

• Sizing from the window unit rather than the clear opening when fully open.
• Meeting the width and height minimums but missing the area requirement.
• Fitting a ladder that intrudes into the required opening.
• Installing a cover that cannot be opened from inside the well.
• Omitting the well drain, or bedding it in soil rather than stone.
• Leaving the ground sloping toward the well.
• Placing furniture or storage in front of the window once the room is in use.
• Working without a permit and discovering it during a sale.

The last two are worth repeating because they happen after the builders leave. An escape route blocked by a wardrobe is not an escape route, however compliant the installation was on the day it was signed off.

Finally, if this is part of a larger project, sequence it early. Our basement finishing cost guide covers where it sits in a wider budget, and cutting an opening after the room is finished costs considerably more than cutting it before.

Frequently asked questions about egress window

Do I need an egress window in my basement?

If the space is used as living accommodation, almost certainly. Bob Vila states that homeowners who use their basements as bedrooms, offices, TV rooms or other living spaces are required to install egress windows. It adds that any room residents live in or use frequently needs one, or a window large enough to be used as an escape during an emergency. This Old House notes that your area’s building codes may require one in a finished basement or any livable space below the fourth floor. Confirm the requirement with your local building department, since codes vary.

What size does an egress window have to be?

This Old House Magazine publishes three code minimums that apply together: a minimum opening width, a minimum opening height, and a minimum opening area. The exact figures are set out in the dimensions table in this guide. The important practical point is that all three must be satisfied at once, that they apply to what the window actually opens to rather than the unit or the rough opening, and that local code governs, so verify them in your own jurisdiction before ordering.

Why can’t I just meet the width and height minimums?

Because the three requirements published by This Old House Magazine operate together rather than separately. An opening at the stated minimum width and the stated minimum height does not reach the stated minimum area, so it fails the third test while passing the first two. In practice at least one dimension has to be generously above its minimum for the area requirement to be satisfied.

Can I install an egress window myself?

Cutting an opening in a foundation wall is not a homeowner job. Bob Vila advises that to ensure windows are installed properly and avoid future water damage and mold growth, it is a good idea to have a professional install egress windows. The structural, waterproofing and drainage aspects all have consequences that are expensive to discover later.

How long does installation take?

This Old House reports that over 40% of its November 2025 survey respondents who purchased egress windows nationwide reported that installation took between two and three days to complete. That matches the sequence of work: excavation, cutting, fitting, the window well and reinstatement all happen in order, and weather affects the outside stages.

Is it worth it beyond the code requirement?

Bob Vila lists a variety of benefits to installing egress windows, such as natural light and ventilation, the addition of an emergency exit, safety, increased home value, and improved aesthetics. Beyond that list, the practical consideration is how a basement room is described and valued when you come to sell, which is worth asking a local agent about rather than assuming.

Sources and how we researched this guide

Research-based. Dimensional requirements are quoted as This Old House Magazine publishes them, and we flag throughout that egress requirements are set by local building code, vary by jurisdiction and are enforced by your local building department. Nothing here substitutes for confirming the requirement locally before work starts. Cost figures are attributed to Bob Vila or This Old House with scope and date. Found something out of date? Tell us and we will check it against the source.

• Bob Vila: Egress window cost
• This Old House: Egress window cost
• Fixr: Egress window cost

Keep planning

• Best Flooring for a Basement: What Survives a Below-Grade Slab
• Basement Subfloor: Why Concrete Needs One and What to Use
• Basement Finishing Cost: Budget by Square Foot and Scope
• Egress Window Cost: Above Ground, Below Ground and Why

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