Pole Building Anatomy 101: Posts, Trusses, Girts & Purlins Explained
The Posts: The Backbone of a Pole Building
Posts are the vertical columns that transfer the weight of the building into the ground. In pole buildings throughout Douglas County WI and St. Louis County MN, posts replace traditional foundation walls.
They are responsible for:
Supporting roof and snow loads
Resisting wind uplift
Preventing settlement and frost movement
Why this matters locally:
In northern climates, post depth, soil conditions, and frost protection are critical. Posts that aren’t set properly can shift over time, especially in areas with clay soil, poor drainage, or shallow frost depth assumptions.
This is one of the most common failure points we see in DIY pole buildings around Duluth and northwest Wisconsin.
Trusses: Designed for Snow Load, Not Guesswork
Roof trusses span from post to post and support the entire roof system.
In Douglas County and St. Louis County, trusses must be designed for:
High snow loads
Local wind exposure
Building width and spacing
Common mistake:
Using trusses that aren’t rated for local snow loads or spacing them farther apart to save money.
The roof may look fine for years until a heavy snow winter exposes the weakness.
Girts: What Keeps the Walls Straight
Girts are horizontal framing members that connect the posts and support wall steel.
They:
Tie the structure together
Prevent wall flexing under wind load
Support siding and interior finishes
In areas like Duluth MN and northern Wisconsin, proper girt spacing and orientation matter because of wind pressure and long wall spans.
DIY builders often don’t think about girts until after the posts are set, when changes are expensive.
Purlins: Supporting the Roof System
Purlins run across the trusses and support the metal roofing.
They:
Carry snow loads between trusses
Provide fastening points for roof steel
Help control deflection and oil-canning
Improper purlin spacing or layout can lead to:
Leaks
Roof movement
Premature wear on metal panels
This is especially important in regions that experience heavy snow accumulation like Douglas County WI and St. Louis County MN.
How the Structure Works as a System
A pole building isn’t just posts and steel. It’s a structural system.
Posts carry loads into the ground
Trusses distribute roof weight
Girts resist wind and wall movement
Purlins support roofing and snow load
Two pole buildings can look identical from the outside and perform very differently depending on how these components are designed and installed.
That’s why comparing pole building quotes purely on price can be misleading.
DIY Pole Building vs Hiring a Local Contractor
If you’re planning a DIY pole building in Douglas County or near Duluth, understanding these components helps you:
Read plans with confidence
Ask better questions
Avoid structural shortcuts that fail inspections
If you’re hiring a local pole building contractor, this knowledge helps you understand why designs, materials, and pricing vary between bids.
Final Thoughts for Local Landowners
Most pole building problems don’t start with bad intentions, they start with missing information.
Understanding the anatomy of a pole building is the foundation for everything else: cost, durability, insulation, and long-term use.
If you’re planning a pole building near Superior or Duluth and want a second set of eyes on your plans, or help deciding whether DIY or hiring a contractor makes sense, we’re always happy to help.