Find a spot for your pole barn. Choose a flat area of solid ground that drains well and does not retain water.
Sketch out your pole barn plans. Build your pole barn in 8-foot sections if you are using commercial lumber. The 8-foot lengths of wood tend to be least expensive.
Acquire a building permit from your municipality. Make sure to tell them that your pole barn is not for human habitation but for agricultural purposes. Municipalities are more lenient in issuing permits for agricultural purposes.
Buy lumber and other hardware. Choose heavy lumber like utility poles for your posts, 2-by-4 inch lumber for the frame, 2-by-6 inch boards for roof stringers, plywood for the walls and corrugated tin for the roof. Pre-built roof trusses (simple framing supports) can be purchased from a lumber yard.
Dig the holes for the posts. Space your post holes carefully using a template to make all of the structure's corners exactly 90 degrees. Place a stake in the center of each hole.
Pour a shallow concrete base into your post holes in areas with loose soil. Add up to 6 inches of gravel fill to allow for drainage in moist areas. Pack down the gravel fill.
Erect the poles of your pole barn. Brace the poles in an upright position until they are secure. Sight down the length of your wall to ensure your poles are installed evenly.
Secure the stringers to the tops of the poles. Secure them well, as these sections must support the weight of both the roof and the trusses.
Install the roof trusses. Support the first truss using poles, rope or braces. Then brace your additional trusses against those previously installed.
Nail in the purlins. These are 2-by-4 inch pieces of lumber secured onto the outer edge of the stringers to help support the weight of the trusses.
Nail in the tin roof using screw-in roofing nails. Overlap short sections of the roofing, both for weather tightness and for ease of installation, and caulk the overlapping sections. Use a tin ridge cap at the peak of the roof.
Install the walls if your pole barn plans include walls. Use 2-by-4 inch lumber as bracing and plywood for the walls.