Wisconsin's Window Well and Areaway Size Rules

Wisconsin's Uniform Dwelling Code sets exact dimensions for a window well (the code calls it an "areaway") serving an egress window. These rules sit in SPS 321.03(6)(e), the same subsection of the code that governs egress window openings generally. This article walks through every figure in that subsection, in full, with nothing rounded or approximated.

Minimum Width

Under SPS 321.03(6)(e)1., the areaway must be at least as wide as the window it serves. There's no separate numeric width floor beyond that — the rule ties the well's width directly to the window's own width, whatever that happens to be for the opening in question.

Minimum Horizontal Projection: 36 Inches

The same subsection, SPS 321.03(6)(e)1., sets a minimum horizontal projection of 36 inches, measured out from the below-grade wall. "Horizontal projection" is the well's depth, front to back — how far it extends away from the house, not how far down it goes. A well that's wide enough to match the window but doesn't project the full 36 inches out from the wall doesn't meet this rule, regardless of its width.

Thirty-six inches is a floor. It's enough room for a person to stand in the well and operate the window, but it doesn't leave much spare space once a ladder is mounted on one side, which is a practical reason many installations end up somewhat larger than the code minimum.

Both figures are measured independently. A well can meet the width requirement — matching the window exactly — while still failing the 36-inch projection if it's shallow front-to-back, and the reverse is also possible: a well that projects well past 36 inches but is narrower than the window it serves still doesn't meet the rule. Both conditions have to be satisfied at the same time, not one or the other.

The Ladder Threshold: 46 Inches

Depth is where a second rule kicks in. Under SPS 321.03(6)(e)4., if the bottom of the areaway is more than 46 inches below the adjacent grade or the top of the enclosure, a permanent ladder or steps is required inside the well. This is a separate trigger from the width and projection rule above — a well can satisfy the 36-inch projection minimum and still need a ladder, purely because of how deep it sits relative to the ground or the top of the well enclosure around it.

For the full discussion of what qualifies as a ladder versus steps, and how to handle an existing well that's already past this depth, see our article on when a window well needs a ladder or steps.

"Adjacent Grade" and the Top of the Enclosure

The 46-inch threshold above is measured against two possible reference points: the grade adjacent to the well, or the top of the well enclosure itself. In most straightforward installations these two points are close to the same elevation, but they can diverge — a well enclosure that extends above the surrounding yard, for instance, changes where that top-of-enclosure line actually sits. Knowing which reference point governs a specific well is part of correctly determining whether a ladder is required, rather than assuming based on a rough look at how deep the well appears from ground level.

Ladder Specifications

When a ladder is required, SPS 321.03(6)(e)5. sets out exactly what it has to meet:

Every one of these figures is a minimum or maximum standard, not a suggestion — a ladder that's rated below 200 pounds, or that has rungs spaced more than 12 inches apart, doesn't meet the requirement even if it otherwise looks adequate.

Drainage: A Separate Requirement, Not an Afterthought

Size and the ladder threshold aren't the only rules that apply. SPS 321.03(6)(e)6. requires that the areaway drain in a way that keeps water from entering the dwelling. A well can be sized correctly and still fail this requirement if it holds standing water against the foundation instead of moving it away.

A Related Rule: Wells Under a Deck or Porch

A smaller number of egress windows sit beneath a deck or porch. When that's the case, SPS 321.03(6)(f) requires a clear path at least 36 inches high and 36 inches wide, no more than 15 feet long, leading from the window to open space. This is a separate requirement from the well's own dimensions above — it governs what's above and around the well, not the well itself — and it only applies where a deck, porch, or similar structure sits over the egress path.

These Figures Apply Regardless of Well Material

Nothing in this section changes based on whether the well is corrugated metal, molded poly, or precast concrete — the width, projection, ladder threshold, and drainage requirements are the same either way. See our window well installation page for how these rules fit into a full installation, including materials and drainage planning.