Basement Types
There are four basement types, named for how the lower level sits in the ground: full, lookout, daylight and walkout. A daylight basement has full-size windows above ground on the side where the ground falls away, and a walkout adds a door straight outside. None of the four count toward a home's above-grade square footage.
To measure a basement's floor area, enter each room or section below.
The four types at a glance
The type depends on how much of the lower level's wall stands above the ground, and that sets how much light and access it gets.
Buried on all sides. Small high windows or none. Works on a flat lot.
Top few feet of wall above ground, so windows sit at ground level outside and about head height inside.
At least a third of the wall buried, the rest partly exposed, with full-size windows.
One wall fully exposed, with a door to the yard. Needs a real slope.
Daylight basement vs walkout
The difference is the door. Both have full-size windows above ground, but only a walkout lets you step outside from the lower level. Snohomish County's code defines a daylight basement as one with at least a third of its perimeter wholly underground, the rest at grade or partly underground, and one or more full-size windows above ground.
Lot slope decides it: a gentle slope exposes enough wall for windows, so you get a daylight basement. For a walkout, the ground has to drop a full story so one wall sits at grade with room for a door.
Listings use the two words loosely, so check the photos: no door to the outside means it's a daylight basement.
Lookout vs walkout basement
A lookout has windows near the top of the wall and no door; a walkout has a whole wall out of the ground with a door. A lookout suits a flat or gently sloped lot, while a walkout needs enough slope for the ground to drop to floor level on one side.
Quick test: stand outside on the low side. Ground at the window sills is a lookout, ground well below the sills is a daylight basement, and ground at the floor with a door is a walkout.
Which types count toward square footage
None of them, finished or not. Fannie Mae's guidance on the ANSI Z765-2021 standard treats a level as below grade if any part of its walls is below the ground, and a walkout's uphill wall almost always is.
Ground at or below the floor on every side = above grade. Anything else = below grade.
Fannie Mae's Selling Guide names the walkout case directly: a partly below-grade walk-out area stays out of above-grade square footage and is adjusted on the appraisal's basement line. A level that is above grade on every side isn't a basement at all, and it counts as a ground floor.
The finished space still has value, recorded on its own line instead of in the gross living area. Does a basement count as square footage has the full rule and how it shows up on a listing, above grade vs below grade explains how the line is drawn, and the ANSI Z765 standard guide covers the rest of the measuring rules.
Common mistakes
No exterior door, no walkout.
The uphill wall is in the ground, so the appraiser takes it back out.
Drywall and carpet make a basement finished. They don't make it above grade.
Keep it as its own figure, split into finished and unfinished. How square footage is measured covers why records disagree.
For the above-grade total, add the main-floor rooms in the house square footage calculator; for other shapes, use the square footage calculator on the homepage.
Frequently asked questions
What is a daylight basement?
A daylight basement is a lower level with at least a third of its perimeter underground and full-size windows above ground where the ground falls away. It has no exterior door.
What is a walkout basement?
A walkout basement is a lower level with one wall fully out of the ground and a door that opens straight to the yard. It's built into a slope.
What is a lookout basement?
A lookout basement sits mostly below ground with the top few feet of wall exposed, so its windows are at ground level outside. It has no exterior door.
Does a walkout basement count as square footage?
No. Part of the level is below grade on the uphill side, so appraisers report it as basement area. Only a level that is above grade on every side counts.
Does a daylight basement count as square footage?
No. Like a walkout, it has walls in the ground, so it's reported as below-grade area, finished or unfinished, separate from the square footage.