At first glance, timber frame and post and beam structures may appear similar. After all, both rely on heavy timber to create open spaces with exposed beams. Yet the difference between timber frame and post and beam construction is the way the individual parts are connected:
- Timber framing uses wood joinery and rarely uses steel parts
- Post and beam structures use metal fasteners and connectors
What Is Post and Beam Construction?
Post and Beam Essentials
Post and beam structures are built with vertical posts and horizontal beams. Metal brackets and steel plates join the timbers and hold the structure together, but they aren’t always visible. In some cases, they’re decorative, but in other cases, they’re structural and placed out of sight.
Pros of Post and Beam
Post and beam building generally has lower skilled labor costs than timber frame construction. Although post and beam structures require plenty of labor, they tend to be less complex in engineering, construction, and fabrication. Additionally, decorative or structural metal plates can add a specific style to a post and beam structure.
Cons of Post and Beam Construction
Moisture can condense on steel surfaces, causing the steel to rust and the surrounding wood to decay. Depending on the complexity of the metal plates, post and beam construction material costs can be more expensive than traditional timber framing. Dissimilar materials (metal and wood) also tend to work loose over time.
What is Timber Frame Construction?
Timber Frame Construction Essentials
Timber frame construction relies on wood-to-wood joinery—so there’s no need for metal brackets. The timber frame is almost always exposed, creating a space that’s simultaneously open and cozy.
Pros of Timber Frame Construction
Usually (but not always), timber frames are more attractive, elegant, and expensive than post and beam structures. Traditional wood-to-wood joinery, if kept dry, can endure for centuries. In addition, traditional wood joinery is somewhat elastic–in other words, it can deflect and give a little under loads. This is one reason that certain examples of Japanese architecture have survived for over a thousand years–despite the destructive earthquakes that occur several times each century.
Cons of Timber Frame Construction
Timber framing has a higher cost of skilled labor to design, engineer, and fabricate traditional joinery. Some structures increase timber cost when timber sizes increase, which may occur during engineering to accommodate joinery.
Post and Beam vs. Timber Frame
What Do Both Methods Have in Common?
Ultimately, timber frame and post and beam structures have a similar visual style. Both tend to create open spaces with exposed beams and natural elegance. That’s because both types of construction use heavy timbers rather than 2x4s.
How Joinery Makes a Difference in Construction
Some timber framers believe that wood should be the only component in a true timber frame structure. When it comes to timber frame construction, mortise and tenon joinery bring everything together—both aesthetically and structurally.
In contrast, post and beam construction uses metal plates and bolts. While that may not seem like a big difference, some would argue that this method isn’t truly timber framing.