Anatomy of a Post-Frame Commercial Building

Post-frame commercial buildings are a top choice across Iowa and the Midwest for their structural strength, quick build times, and long-term performance in challenging weather. They’re cost-effective to build and energy-efficient to operate. They can also be constructed quickly and last a lifetime. Due to state-of-the-art engineering, wood-frame construction can hold up against hurricane-level winds and withstand enormous loads. 

Now that you know why post-frame buildings are gaining traction in commercial construction, let’s explore what makes their structural system so reliable. Next, we’ll break down the components that form them so you can better understand how they perform so well.

What is a Post-Frame Building?

A post-frame building (commonly called a pole barn or wood-frame building) utilizes pressure-treated wooden posts to bear the weight of a roofing system. These vertical posts, along with the roof trusses, make up the main structure of post-frame buildings.

The roof trusses are attached directly to the posts, which are supported by a solid foundation. Purlins and girts provide extra support so the building can withstand vertical and horizontal forces, such as powerful winds. Due to the structure’s interlocking frame, loads (like heavy snow or a second story) are transferred to the ground or the building’s foundation.

What Comprises a Post-Frame Commercial Building?

Let’s dissect each critical piece that makes up a building’s wood-frame construction. This guide will give you a clearer understanding of the core components of a Pro-Line post-frame structure—so you can confidently collaborate with your builder and make informed design choices. 

Posts/Columns

A post is a structural column that is embedded either into a foundation or directly into the ground. The difference between a pole (on a pole barn) and a post, is poles are round while posts are rectangular or square. Posts can be mechanically laminated (smaller pieces of lumber glued or nailed together) or made of solid wood.

Foundation

The foundation supports a building’s columns. Posts are placed in a foundation’s footings, which should be appropriately sized to support the size and weight of the building. Footings help provide resistance to a vertical downward force, lateral force, and vertical uplift force. The distance from the grade line to the base of the footing is known as the foundation depth.

Roof

Aside from a building’s posts, the roof is the most crucial component of a post-frame building. The primary elements of a roof system are trusses, purlins, sheathing, and shingles.

Trusses

Trusses comprise a roof’s structural framework. They form a series of interconnected triangles, like a web, which transfer the roof’s load to the vertical posts. If trusses fail, the building can collapse, so it’s imperative they’re installed correctly.

Purlins

Purlins help structurally support the roof. They span between the trusses to provide framing for the roof sheathing. They work to transfer the load from the roof sheathing to the trusses. They also help resist wind uplift from the inside of the building.

Wall Girts

Girts support wall sheathing and offer extra support to a building’s vertical posts. They run horizontally and are attached perpendicularly to posts. Their main functions are to support posts and to transfer loads from wall sheathing to posts. They also help buildings withstand the force of strong winds.

Splash Board

Splash board, also called skirt board or grade board, is the bottom wall girt. The base of wall sheathing or siding fastens to the splash board.

Siding

Siding is placed on the outside of a building over the wall girts and wall sheathing.

Build with confidence. Build with ProLine.

We manufacture our wood-frame buildings in-house, allowing us to streamline our building process and ensure our materials are premium-grade. Our process uses precision cutting and component optimization to reduce waste, speed up site assembly, and ensure a perfect fit for every Iowa project. We choose the strongest and most durable lumber that can withstand extreme elements and hold up against decay and insect damage. Our turnkey construction process ensures performance, compliance, and peace of mind—from permit to final walk-through.

From rural Iowa townships to regional commercial hubs, Pro-Line delivers high-performance post-frame buildings tailored to your needs. Contact us or explore our completed projects today.