Pole Barn Construction Techniques

One of the most common modern barn styles, pole barns have a lot of construction options so you can build the barn that best serves your property.

by Dave Boyt
PHOTO: robinsan/Flickr

When you think of building a barn, images of a solid post and beam structure with a stone foundation that will stand for centuries may come to mind. But farming is practical. The people who built those barns made the best use of the materials available to them. If sheet metal, power tools, and pre-fabricated trusses had been available, they surely would have used them. While some people do build faithful reproductions of post and beam barns, quick-build pole barns are the way to go if you need the barn quickly at a minimal cost.

Pole Barn Basics

Building a pole barn requires planning. The first consideration, of course, is how big it needs to be. Pole barns are typically built in increments of 10 or 12 feet, such as a 20-by-36 feet. Poles are typically set in the ground like fence posts, so it’s important to use treated lumber, and most of the barn’s strength comes from the sheet metal siding and roof. The truss roof can span up to 30 feet without support, making it an ideal structure for livestock, storage, and repairing vehicles.

While building the barn is straightforward, the design is best left to the experts. Wind, snow loads, defects in lumber and poor construction practices have caused the demise of many pole barns. Fortunately, there are many plans available to help with the structural design. Better yet, there are kits for various sizes that include everything you need for about the same price—or even a little less—than you would pay for the materials if you purchased them separately. Many lumberyards will custom design your barn if you need a certain size.

For building tools you’ll need the basics:

  • framing hammer
  • skill saw (with wood and metal abrasive blades)
  • drill
  • impact screwdriver
  • tape measure
  • post hole diggers,
  • iron bar
  • a lot of old-fashioned elbow grease

Siting Your Pole Barn

The three most important things in real estate, it has been said, are “location, location, and location.” This is certainly true of barns, pole or otherwise. The best location is on fairly flat, level ground, with drainage away from the barn. This may require some land forming before you begin. Other considerations are access to the barn, enough room to maneuver livestock and equipment into the barn, and room to add on to the barn, should that become necessary. Avoid building your pole barn swampy areas or areas that are prone to flooding, especially if livestock is involved.

Choosing Pole Barn Materials

The old saying “you get what you pay for” applies to pole barns. The best materials cost more in the beginning, but they more than pay for themselves with decreased maintenance and replacement costs later.

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Typical posts are 4-by-6 inches or 6-by-6 inches, and should be set at least 30 inches deep in rocky or clay soil and 48 inches deep in sandy soil, which is less stable. Stabilize the posts so they’re perfectly vertical when you fill in around them. It’s imperative that they be pressure treated and rated for ground contact.

Glue-Laminated Posts

Solid-wood posts are the most common, but glue-laminated (or “gluelam”) posts are a viable option. Gluelam posts are strips of wood laminated together with waterproof glue. They’re as strong and durable as solid posts, and are available with just the bottom part treated for ground contact. The cheaper gluelam posts are made of a number of short strips with the joints offset for strength, but are as functional as solid or full-length laminated strips.

Sheet Metal

The sheet metal is available in two common thicknesses or gauges. The lower the gauge number, the thicker the metal—just the opposite of what you would think. The walls of the barn can be made of 29 gauge steel, but it is a good idea to use heavier 26 gauge on the roof to minimize hail damage. Many builders also use the 26 gauge sheet metal for siding of large barns, especially if they will be exposed to high winds.

Installing Wainscot

Wainscot is a second layer of sheet metal that goes from the ground to about 3 or 4 feet high. It protects the exterior metal from bumps by equipment or dents from rocks thrown up by your brush hog, and it can be replaced easily and quickly. For a classy look, consider using a contrasting color for the wainscot layer.

Spacing Barn Columns

Common spacing for the poles is every 10 or 12 feet along the length of the barn and across the ends, but wood trusses span up to 30 feet, so interior supports are not typically required.

Choosing Pole Barn Aesthetics

First and foremost, barns are functional buildings, but here are a few simple additions to make it more pleasing to the eye. A little trim does wonders, and adding a walk-in door and windows will make your barn look more appealing from the outside, as well as improving indoor light and access.

Install A Sliding Door

An enclosed barn needs at least one door for large equipment and round bales of hay, and a sliding door fits this need. Your best bet is to buy a sliding-door kit, which includes all the hardware and instructions. The door should be no more than half the length of the span because the track needs to be supported for twice the width of the door. If this isn’t possible, a bi-fold door or roll-up garage door may be a better choice.

Condensation Control

Barns sweat, especially in the winter, when warm, moist air hits the cold metal. There are two ways to deal with condensation: One is with ventilation (see the section on roof vents below); the other is to isolate the metal from the moist air. The most common isolation material is sprayed foam, which adheres to the metal. “Dripstop” is a rubberized material that is applied to the metal panels before they’re installed. Although it doesn’t add insulation, it does form a barrier that prevents condensation.

Reflective Insulation

Insulation is another way to protect against moisture. Reflective insulation products combine the reflective properties of aluminum with a plastic core, similar to bubble wrap. This type of insulation is relatively inexpensive and easy to apply.

Interior Liner System

If you want to give your pole barn a nice, interior finish, consider metal liner panels, such as the ILM liner. These are available in a variety of colors and textures and can interlock to create a continuous surface. These panels also seal insulation from moisture and rodents.

Soundproofing Materials

If you wish to soundproof your pole barn, there are a number of sound-absorbing materials available. Spray foam insulation is effective, or if you wish to use a steel liner as described above, consider a perforated liner with insulation behind it.

The Pole Barn’s Roof

The roof is the toughest part of the barn to build. If it sounds daunting to lift, line up and brace the 500-pound trusses, hire a crew for this part. A professional crew with the right equipment and experience can safely do in a few hours what could take you a week. Pre-built trusses are economical, save time, and assure consistent quality and size. If you stick with standard sizes, you may find that they don’t cost much more than you would pay for the materials.

Deciding The Pitch

The steepness of the poof, or the “pitch” is described as a ratio of rise to run. For example, a 1:3 pitch (also referred to as a “4 in 12”) rises 1 inch for every 3 inches of horizontal distance. Steeper pitches shed water and snow loads better but require more material and are more difficult to install.

Building Rafters

If you build your own trusses, be sure to use an approved design and materials with the structural grade stamp. Laying them out, cutting them and applying the gussets can be time-consuming and frustrating. Pre-built trusses are economical, save time and assure consistent quality and size. If you stick with standard sizes, you might find that they don’t cost much more than you would pay for the materials.

Attaching Metal

“Stringers” are 2×4 boards that span across the trusses and posts to provide a framework for attaching the metal.

Including Overhangs

Trusses have 6- to 12-inch overhangs built into them to protect the soffits and keep the wind and rain out of the barn.

Ridge Vents

Ridge vents provide an outlet for warm moist air, allowing it to dry any condensation and draw in fresh outdoor air. A classic example of this are the old tobacco drying barns Even a slight breeze draws a great deal of air through the barn.

You have a lot of options when it comes to building your pole barn. With a plan in place and the right help, you can construct a building that will serve your farm for generations to come.

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