Post frame, pole barn, engineered truss system, Barndominium. Whatever you call it, this framing system will produce a building that is attractive, versatile, and durable.
Barndominiums are built using either steel frame or post frame construction. They have reached widespread popularity only in recent years. It’s not surprising, then, that there is some confusion about this construction method and how it differs from conventional construction. Let’s focus for now on post frame systems.
Post frame construction uses an engineered wood frame system and is more common in the North and Midwest United States, while steel frame construction is commonly found in the Southern region of the country. Post frame systems offer many advantages over traditional construction methods. Perhaps the most significant advantage is that Barndominiums allow for greater free spans than traditional construction methods without the need for load bearing walls. This affords tremendous versatility for design of the interior space.
Emily and Paul Marshall of MR Post Frame (also known as Marshall Remodel), built their own post frame Barndo in Winterset, Iowa. Emily says, “in the upper Midwest, post frame Barndominiums are a traditional agricultural style.” So, this was an authentic home style true to their Midwest roots. One of the benefits of this type of construction style according to Emily is that it does well in climates with extreme weather. Its ability to limit thermal transfer makes it a “solid way to protect the home so it functions properly with extreme weather changes.” She says this results from the way a post frame building is insulated and protected. The vapor barrier is an important element. The greater the difference in temperature between the inside of the home and the outside air, the more quickly the water vapor in the warm inside air will condense. This makes vapor barriers especially important in cold climates.
According to the National Frame Building Association (NFBA), post frame structures are efficient builds because “the larger posts and the interlocking frame can handle greater loads than stud-wall construction. [F]ewer structural materials are needed which saves time and other costs. Also, because posts are spaced farther apart than studs, post frame buildings feature an exceptionally large wall cavity and provide ample room for insulation, lowering heating and cooling costs through the life of the building.”
Emily explains that a benefit of post frame construction over steel frame is that it can be easier to find a general contractor to build your Barndo. That’s because contractors are more accustomed to working with wood than with steel and there is no need for welders or for knowledge of erecting a bolt-up system. Post frame systems also offer more opportunity to individuals who want to self build because knowledge of steel construction and/or welding is not necessary.
Emily says that the process of ordering supplies for a post frame Barndo is a little different from other types of build. It is not uncommon to order steel, columns and trusses from one supplier and order any additional exterior framing and interior framing materials from a different supplier, usually a lumberyard. In the North and Midwest, there are many places from which to order the engineered trusses. Lumberyards or truss manufacturers enter calculations for your loads, spacing and spans, then determine how to properly engineer the trusses. Steel suppliers often prepare a “kit” for the frame but that approach is not as common with post frame construction. However, Emily says that “post frame kits are an option through some large pole barn companies, and someone can also piece together their own project and find the best cost options.”
There are several foundation options when building post frame Barndominiums. Emily discourages placing posts directly in the ground. “Wood rots, even treated lumber, unless it is above ground” she says. Plus, “for traditional lending purposes, you are required to have all of your wood posts out of the ground.” She and husband, Paul, always recommend putting columns on a continuous masonry footing or using concrete pier footings and securing each footing using wet set brackets (metal brackets which are the right size for the column and go into wet concrete while it is setting up). Continuous footing is a popular option for unpredictable soil and terrain, and Emily adds that in cold climates “it must be paired with a continuous frost wall to protect the home from subzero temps and months of frozen ground. It is not uncommon for this method to require excavation 7-9 feet deep. Wood posts are secured with brackets to the top of the frost wall.” Emily says using pier footings where possible can save money. She also says that “building over a basement is another option chosen by some, but we’ve found that it takes away from the cost effectiveness post frame offers.”
Steel frame construction, also known as pre-engineered metal buildings (PEMB), have their own advantages such as structural strength, resistance to rot and termite damage, and the ability to support wider spans. But a couple advantages of post frame over steel frame is that most fully engineered post frame Barndos include foundation plans; whereas steel frame designs usually require you to hire a foundation engineer for the foundation plan. Also, post frame systems are more easily adaptable to complex rooflines than steel frame.
Wood or steel sidewalls are most common on post frame Barndominiums, but according to the NFBA, “almost any type of exterior façade may be installed on post frame buildings, which can be designed to meet the highest standards for quality and aesthetics.”
Regarding costs to build a post frame Barndo, prices adjust as the cost of lumber fluctuates. Style and location of the home also affect price. But, today, on average, in the Des Moines area, Emily says cost for a simple exterior structure is $25-$30 per square foot including porches depending on the complexity and quality of windows, doors and other materials. This is for the frame only and does not include foundation, plumbing, electrical or finish out. And, high end doors, taller ceilings, or custom windows will cost more.
For more information on post frame construction, visit the National Frame Building Association website at www.nfba.org or follow Emily and Paul Marshall on their YouTube channel MR Post Frame (also known as Marshall Remodel).