Window wells for egress windows: size, depth, ladders and drainage

An egress window well needs at least 9 square feet of floor area, at least 36 inches of width and 36 inches of projection from the wall.¹ The window must still open fully inside it. A well deeper than 44 inches needs a permanently affixed ladder or steps.¹ The well should drain into the foundation drain unless the soil drains well. Those are 2021 International Residential Code rules.¹ Your city may use another edition or amend them.

TL;DR

• Measure the inside of the well at its narrowest point. A well can pass 9 square feet on area and still fail the 36 inch width or projection rule.¹
• Depth is what adds the ladder. A ladder or steps can take up only 6 inches of the required space, so bulky steps need a bigger well.¹
• Poor drainage around a well can lead to water leaks.² Get the drain connection written into the quote.
• Metal wells cost least, while composite and stone cost more for looks.² The code is silent on material.¹
• Budget $6,000 to $8,000 for a finished egress window with its well, the average range in HomeGuide's national cost guide.²

What is the code for egress window well size?

Under the 2021 International Residential Code, section R310.4.1, an egress window well must have a horizontal area of at least 9 square feet.¹ It must be at least 36 inches wide and project at least 36 inches from the wall.¹ It must also be big enough for the window to open fully.¹

The code calls this an "area well". By our arithmetic, a 36 by 36 inch well works out to exactly 9 square feet (1,296 square inches divided by 144). So a square well at the minimum size passes on area, width and projection at once. Any short dimension fails, even when the area adds up. A well 44 inches wide with 30 inches of projection works out to about 9.2 square feet, yet it fails the projection rule.

The window inside the well has its own minimums, which our egress window requirements guide covers in full. Here is the full set from the 2021 IRC in one place.

Source for every row: the 2021 IRC, chapter 3.¹

Local adoption and amendments vary. Your contractor should confirm which code edition your building department uses before ordering a well.

How deep does a window well need to be for an egress window?

A window well needs to reach below the window's bottom edge, so the window's position sets its depth. The 2021 IRC sets the well's floor area, width and projection. It uses depth for one thing: a well deeper than 44 inches must have a permanently affixed ladder or steps.¹

The code caps the window sill at 44 inches above the basement floor.¹ Where that sill sits against the ground outside sets how far down the well goes. If the ground outside is only a little above the sill, the well can be shallow. If the ground is far above the sill, as in a deep basement, the well can run deep enough to need a ladder.

The well floor also sits a little below the sill, with room for drainage under it. So the finished well tends to run deeper than the gap between sill and grade. That extra depth can push a borderline well past the ladder trigger. Ask for the planned well depth in writing so you know whether it needs a ladder.

When does an egress window well need a ladder or steps?

An egress window well needs a ladder or steps once its vertical depth is greater than 44 inches.¹ The 2021 IRC, section R310.4.2, requires them to be approved and permanently affixed. The open window can't block them. Below that depth, the code doesn't require either one.¹

The code then gives two options with separate dimensions.¹

Ladders

Rungs need an inside width of at least 12 inches.¹ They must project at least 3 inches from the well wall.¹ They can be no more than 18 inches apart, measured center to center, for the full height of the well.¹

Steps

Steps also need an inside width of at least 12 inches.¹ Each tread must be at least 5 inches deep.¹ Each riser can be no more than 18 inches tall, again for the full height of the well.¹

Steps take more room than a ladder, and the room is limited. The exception in R310.4.1 lets the ladder or steps encroach no more than 6 inches into the required well size.¹ If your steps stick out further than that, the well has to grow.

The ladder or steps don't have to follow the stair rules for the rest of the house.¹ So a narrow rung ladder can pass in a well even though it would fail as an interior stair.

Check how the ladder attaches. Some ladders hang from hooks at the top of the well, while the code wording is "permanently affixed."¹ Ask your contractor whether your inspector accepts a hook-on ladder or wants it bolted.

How should an egress window well drain?

An egress window well should drain into the house's foundation drainage system. The 2021 IRC, section R310.4.3, requires that connection. The one exception covers foundations on well-drained soil or sand-gravel mixes listed as Group I soils in the code's table R405.1.¹

A well is an open pit next to your foundation. Rain and snowmelt land in it. If that water can't leave, it sits against the window and the wall cut. HomeGuide's cost guide notes that poor drainage around window wells can lead to water leaks.² The same guide prices a drainage system at $1,000 to $4,000.² It also flags extra waterproofing around the window and the foundation cut where rainfall is heavy or the water table is high.²

Points to settle in your quote:

• Ask how the well floor connects to the foundation drain, and where that drain discharges.
• If your contractor plans to rely on the soil exception, ask how they know your soil is Group I.
• Keep gutters and downspouts pointed away from the well. Grade changes, like a new patio, can send water toward it.
• If your basement already takes on water, fix that before cutting a new opening in the wall.

For the window itself, from sizes to styles, see our basement egress window guide.

Does an egress window need a well?

An egress window needs a well only when the bottom of its opening sits below the ground next to it. The 2021 IRC, section R310.4, requires an area well in that case.¹ A window with its sill above grade, such as on a walkout wall, needs no well.

HomeGuide notes that basement egress windows are the most common type, and that a below-grade window requires excavation for a window well, which adds to the project cost.² Where the site allows it, a door can serve instead of a window. The 2021 IRC lets a side-hinged or sliding door act as the escape opening.¹

What are the different types of egress window wells?

Egress window wells come in corrugated metal, composite and decorative stone, in curved, rectangular or custom shapes. Corrugated metal is the cheapest. Composite and stone look better and cost more.² Homeowners also mention timber and molded wells as options.³

Shape matters more than most people expect. A curved well can meet the 9 square foot area and still fall short on width or projection. Measure the inside of the well at its narrowest point.

Which is better, plastic or metal window wells?

Neither material is better under the code. The 2021 IRC sets the size, ladder and drainage rules and says nothing about the well's material.¹ The choice comes down to budget, looks and how your contractor will fasten and backfill the well.

Metal wins on price. HomeGuide calls standard corrugated metal wells the most affordable type.² It says composite wells cost more and are chosen for curb appeal.² HomeGuide gives no separate price for plastic wells.

Strength claims come from the sellers. Read them as sales claims, and ask your contractor what they install on your soil and why.

If the well sits on a wall you see every day, composite or stone may be worth the extra. If it faces a side yard, a metal well puts that money toward the window or the drainage.

Can you put a cover on an egress window well?

Yes, you can cover an egress window well, as long as someone inside can remove or release the cover. Under the 2021 IRC, section R310.4.4, covers, grates and bars must come off from inside with no key, no tool and no more force than opening the window takes.¹

A cover also can't shrink the escape route below the well and window minimums.¹ Clear polycarbonate covers are popular because they're durable and let light through. Metal grates add security but block more light.²

A cover keeps debris, rain and snow out of the well.² The code's drainage rule still applies to a covered well.¹

What does an egress window well cost?

A finished egress window with its well costs $6,000 to $8,000 on average in HomeGuide's national cost guide.² The minimum is $4,000 and the maximum is $12,000.² The guide says the total depends on the window, the well material and style, the foundation, the site and local labor rates.²

The published figures from the same guide:²

A second HomeGuide page lists an egress window at $3,000 to $7,000 installed in a table of window types.⁴ The same page also puts a basement egress window at $6,000 to $8,000 installed, "including the window, a window well, excavation, and installation labor."⁴ Budget from the $6,000 to $8,000 range, the figure that states it includes the well and the dig.⁴

How do you check a window well kit against the code?

Check a well kit against the 2021 IRC one rule at a time: floor area, width, projection, window swing, then depth and ladder. Drainage is the one rule no kit can meet on its own.

As an example, take a kit that lists a well 42 inches wide, with 36 inches of projection and 48 inches of depth.

1. Area: by our arithmetic, 42 times 36 is 1,512 square inches. Divide by 144 and that works out to 10.5 square feet. That clears the 9 square foot minimum.¹
2. Width and projection: both meet the 36 inch minimum.¹ The projection meets it exactly, so the 6 inch ladder allowance is the only slack the code gives.¹
3. Window swing: an in-swing casement window opens into the room, so it can't hit the well. HomeGuide notes inward-swing windows suit wells too small for an outward-opening design.²
4. Depth: at 48 inches deep, the well is past the 44 inch trigger and needs a ladder or steps.¹ If the kit ladder hangs from hooks, confirm your inspector accepts that as permanently affixed.
5. Drainage: the tie-in to the foundation drain happens on site.¹

A kit covers the parts you can order. The drain, the wall cut and the backfill happen at your house, and they decide whether the basement stays dry.

Which basement rooms need an egress window?

Under the 2021 IRC, section R310.1, every basement needs at least one emergency escape opening, and every basement sleeping room needs its own.¹ Storm shelters are exempt, and so are basements used only for mechanical equipment and no larger than 200 square feet.¹

If you're finishing an existing basement, section R310.7 narrows that. New sleeping rooms need an escape opening. Other alterations or repairs to an existing basement don't trigger one.¹ A house with a full sprinkler system can also skip escape openings in basement sleeping rooms, if the basement has the exits the code lists.¹

So the bedroom decision drives the egress decision, which our basement bedroom egress window guide covers. Plan a bedroom or a rental unit, and you plan an escape opening, plus a well if the window sits below grade. If the space will be a rental or an in-law suite, see our page on basement apartments and in-law suites. Local codes can go further than the model code, so check with your building department.

What to ask your contractor about egress window wells

A good egress quote names the well size, the well depth, the ladder or steps, and the drain connection. It also names the permit. HomeGuide notes that most municipalities require permits for egress windows because the work modifies the foundation.² Your contractor pulls the permit and books the inspections.

Ask these before you sign:

• What are the inside width, projection and depth of the well?
• Will the well be deep enough to need a ladder? If so, is it a ladder or steps, and how is it fastened?
• Does the open window clear the ladder and the well walls?
• How does the well floor drain, and where does that water go?
• What material is the well made of, and why that one for this wall?
• Which IRC edition does the building department use, and are there local amendments?
• Does the price include landscape repair and interior trim around the window?

HomeGuide lists landscape restoration and interior finishing as common add-on costs.² Get them in the written quote so they don't show up later.

If an egress window is part of a bigger plan, Basement Remodeling Co. can match you with one vetted, licensed basement contractor for your area. You get a free on-site estimate and a written, itemized quote, and nothing starts until you sign. Get a written quote for finishing your basement, or find a basement contractor by ZIP code. Local pages cover finishing a basement in Denver and finishing a basement in Atlanta.