What an egress window is — and which rooms need one
An egress window (the code calls it an “emergency escape and rescue opening”) is a window large enough and low enough for a person to climb out in a fire, and for a firefighter in gear to climb in.
Under the International Residential Code (IRC), which most U.S. states and counties adopt with local amendments, every sleeping room needs at least one, and so does a basement — including a basement with a bedroom or habitable space. A door directly to the outside can serve instead of a window.
Egress window minimum sizes
| Requirement | IRC minimum |
|---|---|
| Net clear opening | 5.7 sq ft (5.0 sq ft for windows at grade floor level) |
| Net clear height | 24 inches |
| Net clear width | 20 inches |
| Sill height | No more than 44 inches above the floor |
| Operation | Opens from inside without keys, tools or special knowledge |
“Net clear” means the actual open hole when the window is fully open — not the rough opening, and not the glass size. That's why a window that looks big on paper can still fail. Note that 20″ × 24″ alone is only 3.3 sq ft; you need a larger size in at least one direction to reach 5.7 sq ft.
Which window types usually meet egress
| Window type | Egress? | Why |
|---|---|---|
| Casement | Usually the easiest | Opens nearly the full frame, so a moderate size can meet 5.7 sq ft. |
| Single- or double-hung | Only if tall enough | Only one sash opens, so you get roughly half the frame. Needs a tall unit. |
| Horizontal slider | Only if wide enough | Only half opens; width matters most. |
| Fixed / picture | No | Doesn't open. Pair it with an operable unit if the room needs egress. |
| Awning / hopper | Rarely | The sash blocks much of the opening. |
Manufacturers publish the net clear opening for each size — check it rather than guessing from the frame size. In a group of windows (for example a triple), one operable egress unit is enough.
Basement egress and window wells
Below-grade egress windows need a window well so the opening is usable. Common IRC requirements:
- The well gives at least 9 sq ft of floor area, with at least 36 inches of projection from the wall and 36 inches of width.
- Wells deeper than 44 inches need a permanent ladder or steps.
- Well covers or grates must open from inside without tools.
- Drainage so the well doesn't fill with water.
Planning a finished basement or walkout? See walkout basement house plans — a walkout door can serve as the escape opening.
Egress, stairs, halls and clearances are part of our 40+ point review. Get a marked-up PDF with every red flag and the fix in 3 business days.
See how plan review worksHow to check egress on your house plan
- List every room that could be used for sleeping — including offices, dens and bonus rooms that may become bedrooms later.
- Find each room's windows on the plan and in the window schedule.
- Check the window type: fixed units don't count.
- Look up the manufacturer's net clear opening for that size and type.
- Check the sill height on the elevations — especially on upper floors and in lofts.
- For basements, confirm the well size and ladder.
Our window and door schedule guide explains how to read sizes like 3050 or 2040.
Common egress mistakes we see in plans
- Bedroom windows drawn as fixed transoms or picture windows.
- Small 2040 single-hung units that look fine on the plan but open too little.
- High windows in bedrooms above a bed or dresser, with sills well over 44″.
- Loft or bonus rooms used as bedrooms with only a skylight.
- Basement bedrooms with no window well shown at all.
- An “office” that is clearly a future bedroom with no qualifying window.
Each of these is easy to fix on paper and expensive after the wall is framed. Egress is one of the 40+ checks in every professional plan review.
Frequently asked questions
What size window is required for a bedroom?
Under the IRC, at least one opening with 5.7 sq ft of net clear opening (5.0 sq ft at grade floor), at least 24 inches of clear height and 20 inches of clear width, and a sill no more than 44 inches above the floor.
Does every bedroom need an egress window?
Under the IRC, every sleeping room needs an emergency escape opening. An exterior door can serve instead of a window.
Can a double-hung window be an egress window?
Yes, if the open sash alone meets the net clear opening, height and width minimums. Because only half the window opens, it usually has to be a tall unit.
Do basements need egress windows?
Under the IRC, basements and every basement sleeping room need an emergency escape opening, with a window well of at least 9 sq ft and a ladder if deeper than 44 inches.
Are egress rules the same in every state?
Most states adopt the IRC, but many amend it. Always confirm the current requirements with your local building department.