Post Frame Building Definition

by Aaron Halberg, P.E.
Halberg Engineering LLC

What is a Post Frame Building? It is essentially a structural framing system used in a wide variety of building applications. More people every day are becoming aware of the economic and environmentally sustainable advantages of Post Frame construction. To address the need for a clear definition of the Post Frame Building system, the following definition was recently approved by the National Frame Building Association (NFBA) Technical & Research committee under the guidance of Dr. Harvey Manbeck:

"Post-Frame Building System. A post-frame building system is characterized by primary structural frames of posts as columns and trusses or rafters as roof framing. The roof framing is attached to the posts, either directly or indirectly through structural headers. Posts are typically graded lumber, graded timbers, laminated lumber or fabricated of composite or hybrid material. Posts are embedded in the soil and supported on isolated footings, or are attached to the top of piers, concrete or masonry walls, slabs-on-grade, or other suitable foundations. Secondary framing members, purlins in the roof and girts in the walls, are attached to the primary framing members to provide lateral support and to transfer sheathing loads, both in-plane and out-of-plane, to the posts and roof framing. Structures are sheathed with a wide variety of materials, including metal and wood structural panels or other suitable materials."

Post Frame buildings are cost effective and enviornmentally sustainable because they use a large amount of renewable structural material and use all materials very efficiently compared to alternative framing systems. Post Frame buildings can be finished with the same interior and exterior finishes of any other framing system or, for ultimate cost savings, they can be covered with light gauge steel panels (similar to pre-engineered steel buildings) which serve as both exterior finish and structural element (replaces the OSB and lap siding with just one material). The material efficiency of Post Frame construction does require a higher degree of certainty in the engineering than other types of construction having more built-in redundancy.

Halberg Engineering is an independent structural engineering consultant specializing in the engineering of Post Frame buildings in a wide variety of applications: commercial, residential, and agricultural. If you have any questions or engineering needs for Post-Frame construction give us a call at 866-694-8602 and ask for Aaron.

Environmentally Friendly Materials and Practices

A great definition of sustainable construction was presented by Professor David Bohnhoff at this year's Wisconsin Frame Builders Association conference during his discussion of "green" practices:
"Sustainable Construction meets present needs without compromising the ability of future generations to meet their own needs."

Prof. Bohnhoff also pointed out that, in almost every measure, when you look at the factors that go into making a building the most affordable it can be, you are also making the building the most environmentally friendly that it can be. This is a direct result of the fact that much of the cost that goes into a project reflects the recouping the costs of the embodied energy, or the energy required to produce, use, and dispose of the building at the end of its life. The less energy required, the lower the impact on the environment, and less energy also translates to lower cost. Post frame construction is a Win-Win-Win in this regard.

In another point of the discussion, minimizing the life cycle energy costs to condition our occupied spaces leads us to make our spaces as energy efficient as possible to start using less energy per unit of occupied space as soon as possible. This is basically a reason to perform construction sooner than later at any time as improvement in energy efficiency serves as a positive return on investment with constant energy costs, but that return rate would improve in a scenario of increasing energy prices.

So, if you're going to build a structure that uses less energy to condition, you should also look at minimizing the total material usage (embodied energy) that goes into the building. Some types of structures are not particularly efficient, including Timber-frame construction and even full log construction if the logs are harvested, debarked and shpaed on a site away from the buildnig site. The amount of material used can be minimized in our building shapes by looking at regular shaped buildings with good aspect ratios (length to width), not too square (inefficient for natural lighting and structural framing) yet not too narrow (inefficient for energy loss because of high exterior wall area per unit of floor area).

Post Frame construction is just one of many options for energy efficient and environmentally friendly construction although it is obvious that wood material is a replenishable resource (trees, switchgrass, corn: all are "biomass"). But even concrete can be made in more environmentally friendly today when the heat used to produce the concrete is recovered waste heat from other emission systems. This drastically lowers the embodied energy in concrete.

Professor Bohnhoff made some great points about why we should be very wary of mandated green building standards as we've seen over and over again that standards tend to stifle creativity and innovation, which is really what leads us to improvements in all areas of our society. The man-made impact on Global warming should be held in suspicion as many of the promoters of that theory are using more fear and less facts which seems to move towards mandated standards to combat such a large problem, regardless of the cost of implementing those standards.

In so many ways, there are reasons to be optimistic about the future of the built environment as the quality of materials improve, innovative use of energy continues, and intelligent choice of building design continues to get better.