ONeil Building Systems


A house that looks like a barn, with connecting breezeway to three car garage and three-seasons room.

Farm & Equestrian

This is an old barn that we gave new life, by installing new roof and wall metal.


Manufacturing buildings, business offices and more.


Pool houses, park structures and more.

Building Custom Post-Frame Structures

Our buildings all look good, but the real beauty of working with O’Neil Building Systems is expressed in our philosophy: “If you can dream it, we can build it!” And that’s exactly what we’ve been doing for satisfied customers in Illinois, Missouri, and parts of the Midwest.

Here you can learn more about the wide variety of materials and options available to create the building you want. And if your dream building includes a design feature you don’t see here, give us a call at (800) 489-6533 or (618) 337-6100.Chances are we can include it as a part of your new building!

Door Systems

Do you need access for people, cars, horses, forklifts, or airplanes? We offer door systems to accommodate whatever you’re moving in and out of your building. Options include customary personnel doors – with and without windows – overhead, ‘garage-style’ doors, and even aluminum-framed sliding doors of nearly any dimension.

Whatever your design and functional need, we can provide a top-quality door system to satisfy it.


Here the selection really is nearly limitless. We use only top-of-the-line, commercial quality windows from PLYCO and TEMPCO which are made specifically for post-frame steel buildings. PLYCO’S windows are constructed of 100% thermalized aluminum extrusions with 3/4-inch thermo pane glazing, and are available in horizontal slider, vertical single hung and fixed lite (picture window) styles. TEMPCO’S windows are an all vinyl constructed window with insulated and non-insulated glass available. Integral J channel and weatherstripping. These windows come in single hung, slider and fixed.

These windows come in a variety of sizes, and glass options such as low E, tinted, grids, safety glass and tempered can also be provided.

Siding and Roofing

The outer surface of your building is an essential component of both its protection and appearance, and at O’Neil we’re proud to use only high-performance products from our manufacturing partners Central States Manufacturing, Everlast Roofing and American Building Components-ABC.

Our roofing and siding products are engineered to stay bright, tight and durable for years to come and feature crisp chalk free colors with appealing profiles. The heart of our panels are primarily galvalume substrate.


We offer a wide range of colors and paint finishes from siliconized polyester to kynar.

central states manufacturing colors
paint finish colors pole barns

Seamless Gutters

Conventional gutter systems of durable, seamless aluminum and steel in a wide range of colors are available to accent and complement your building design


We use aluminum soffits – available in a range of long-lasting finishes in a variety of colors – to provide your building with efficient airflow while enhancing its appearanc.


Whatever the design, nothing caps off a building quite like a beautiful cupola. Available in a wide array of colors and designs, our cupolas can include active vent louvers, glazed side windows, and even your choice of stylish weather vane for that perfect finishing touch.


O’Neil Building Systems Lean-Tos are a great way to protect large pieces of equipment alongside your new building or provide shelter from the elements for people and animals. These optional features can be designed in a wide range of styles, materials, and sizes. They also add functionality and value to any building.

Concrete Flooring

Traditional Post-frame structures (or “Pole Barns,” as they’re sometimes known) often have bare dirt or gravel floors – perfect for livestock barns and equestrian structures. But for dozens of other applications, nothing short of a finished concrete pad will do for the interior of your building.

O’Neil can provide whatever type, size, and style of concrete flooring for your building, as well as any other kind of interior build-out, from interior offices to finished living spaces

Our Partners

We’re proud to be manufacturing partners with some of the leading companies in the industry. The options they provide let us create whatever size, style, and building finish you desire.

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