Parts of a Pole Barn – Labeled Post-Frame Diagram

All 12 parts on the diagram

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The frame 7

Posts (poles) Large poles or squared posts set in the ground. They carry the roof and the walls. They stand in a row down each long wall, with gaps left for doors.
Girts Fastened across the outer faces of the posts, they carry the siding.
Skirt board A board wider than a girt, at the foot of the wall. The bottom of the siding is nailed to it. Also called skirt planking.
Purlins They carry the roofing. Fastened across the tops of the trusses or rafters.
Girder One runs along each side of the post tops. The trusses or rafters rest on the pair. It is how the roof load reaches the posts.
Truss A frame of timbers joined into triangles. One sits over each pair of posts and carries the roof across the width of the building.
Knee braces Each ties a post to the truss above it. It stiffens the building across its width.

Skin and door 3

Siding Most often ribbed steel sheets, fastened to the girts. Wood and other sidings are used too.
Roofing Usually metal sheets like the siding, fastened to the purlins.
Sliding door It opens by sliding sideways on a track above it. Swinging and overhead doors are used as well.

In the ground 2

Footing A concrete pad at the bottom of the hole. The post stands on it, and it takes the weight that comes down the post.
Concrete collar Concrete cast round the base of the buried post. It helps keep wind from lifting the post out of the ground; wood cleats do the same job.

How this list was compiled: Part names checked on 2026-09-30, a name kept only when two independent sources use it. (1) Northeast Regional Agricultural Engineering Service, Pole and Post Buildings (NRAES-1; Cornell University, University of Vermont and other land-grant universities; 1976, revised 1984), full text at https://archive.org/details/post-frame-building-handbook-1997 (posts and poles, footing, concrete collar, spaced girder or plate, roof truss, knee braces, purlins, girts, skirt planking, roofing and siding, ridge cap, sliding doors). (2) National Frame Building Association, Post Frame Architectural Terms Glossary (2024), https://www.nfba.org/aws/NFBA/asset_manager/get_file/896998?ver=0 , and its Post-Frame Construction Guide, https://nfba.org/aws/NFBA/asset_manager/get_file/884452?ver=0 (posts as columns, isolated footings and footer pads, wood cleats or concrete collars, girders, trusses, knee brace, purlin, girt, skirtboard, steel siding and roofing, sliding door on a track). (3) Wikipedia, Pole building framing (poles or posts, footings, girts carrying the siding, truss roof supporting purlins, metal roofing and siding). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no builder's plan, nothing traced. Licence: own work

How it works

The parts of a pole barn hang on its posts. There is no stud wall and no continuous foundation: posts set in the ground carry trusses, and boards across them carry a metal skin.

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From the ground up

On the cut, each post stands on a footing with a concrete collar round its foot. At the top, a girder each side of the posts carries the truss, and a knee brace ties each post to it. The first drawing shows what goes across them: girts and a skirt board on the posts for the siding, and purlins on the trusses for the roofing.

Girts run across posts and purlins run across trusses; both do the same job for the skin.
Builders also call this post-frame construction, and the building a pole building.

Questions and answers

What are the parts of a pole barn called?

Posts set in the ground on footings, girts and a skirt board across the posts, a girder along the post tops, trusses with knee braces, purlins across the trusses, and siding and roofing, usually of ribbed steel.

What is a girt on a pole barn?

A board fastened level across the posts. A row of girts up the wall carries the siding, and they brace the posts sideways. The matching boards on the roof are called purlins.

What is a skirt board on a pole barn?

The wide board at the very bottom of the wall, fastened to the posts at ground level. The bottom edge of the siding is nailed to it, and it is made of pressure-treated wood.

Why is it called a pole barn?

The first ones, in the United States in the 1930s, were farm buildings framed on utility poles. Most are now built on squared, pressure-treated posts, which is why builders say post-frame.