Window Well Materials Compared: Metal, Poly, and Concrete

Window wells come in three materials that cover most installations: corrugated galvanized steel, molded polyethylene (poly or plastic), and precast concrete or masonry block. All three can be built to Wisconsin's width, projection, and drainage requirements — the material choice doesn't change what the code demands, only how the well performs and holds up once it's in the ground.

Corrugated Metal

Corrugated galvanized steel is the most common window well material, and for good reason: it's lightweight relative to concrete, comes in a wide range of sizes and shapes, and is straightforward to fasten to a foundation wall. The corrugation adds rigidity against the soil pressure behind it without needing a thick, heavy panel.

The tradeoff is corrosion. Galvanized coatings resist rust for a long time, but they're not permanent, especially where a well holds moisture against the metal or where road salt and lawn chemicals reach the soil around it. A metal well that's been in the ground for a couple of decades is a common candidate for replacement once rust starts compromising the panel rather than just its finish.

Molded Poly / Plastic

Poly window wells are molded from UV-stabilized plastic, usually in a one-piece or interlocking-panel design. Because they don't rust, they hold up differently than metal over the long term, and their lighter weight makes them easier to handle during installation. Poly wells are also less prone to developing sharp edges or rust-weakened spots that could catch clothing or skin over time.

The material's flexibility is also its limitation: a poly well depends more on correct backfill and support behind the panel to hold its shape under sustained soil pressure than a rigid metal or concrete well does. UV exposure over many years can also make some poly products more brittle at the exposed edge, which is worth checking on an older installation.

Precast Concrete or Masonry Block

Concrete and masonry wells are the most rigid option, built either as a precast unit set into the excavation or as a block structure built in place. They resist soil pressure and impact better than metal or poly, and they don't corrode or degrade from UV exposure the way the other two materials can.

Concrete's rigidity is also why it doesn't flex or absorb minor ground movement the way metal or poly can — a poured or block well that develops a crack from foundation settling or frost movement stays cracked until it's repaired, rather than flexing back into shape. Precast and masonry wells are also heavier and less commonly used than metal or poly for a straightforward egress well retrofit, though they show up more often where a well is being built into new foundation construction from the start.

Drainage Behaves the Same Way Regardless of Material

Whatever material a well is built from, Wisconsin's code requires it to drain so water doesn't reach the dwelling, under SPS 321.03(6)(e)6. That requirement doesn't change based on whether the well itself is metal, poly, or concrete — drainage is a function of the gravel base, backfill, and any drain line beneath and around the well, not the well's wall material. A well built from the most durable material available can still fail this requirement if the ground beneath it doesn't drain properly.

Materials and Well Covers

Material choice also affects how a well cover fits and performs. Corrugated metal and poly wells typically use covers designed around their specific lip profile, while a concrete or masonry well may need a more custom-fitted cover. Whatever the material, a cover has to be installed so it never obstructs the window as an emergency exit.

How Foundation Type Affects Material Choice

The type of foundation wall a well attaches to also factors into which material makes sense. A poured concrete foundation gives a flat, consistent surface for fastening a metal or poly well, while a block or stone foundation can have a less even surface where a rigid, custom-fit well may seat more securely than a flexible one. Older stone or fieldstone foundations, in particular, sometimes call for a more custom approach to how the well meets the wall, regardless of which of the three main materials is chosen.

Longevity and What Shortens It

None of these materials fails purely on a fixed timeline — how long a well lasts depends heavily on drainage, backfill quality, and how much water and salt exposure it sees over time, not just the material itself. A metal well with excellent drainage around it can outlast a poorly drained one by a wide margin, and the same is true in reverse for poly and concrete. That's part of why drainage planning matters as much as material selection when a well is first installed, rather than being treated as a separate decision.

Choosing Between Them

There's no single right material for every situation. A straightforward egress retrofit on an existing foundation is commonly done in metal or poly for ease of installation and handling, while a well built as part of new foundation work, or one that needs to match a specific aesthetic or hold up to unusual soil pressure, is more likely to use concrete or block. A local installer looking at the specific foundation, soil, and depth involved is better positioned to recommend a material than a general rule. See our window well installation page for how material selection fits into a full installation.