Why Post and Beam Construction is the Simplest Solution

Why Post and Beam Construction is the Simplest Solution

By Bud Dietrich AIA, Houzz

Simple and transparent while being an elegant expression of craft, post and beam construction has a lot to offer. It's one of my favorite building methods.

First, post and beam construction is just so simple. We just can't get any more direct than having vertical posts that hold up horizontal beams, all made of wood. It's a directness that can result in visual elegance, as the resulting structure molds space to form rhythms and patterns, while defining rooms. 

Second, the simplicity of the basic structure gives rise to opportunities to explore how connections are made. These connections, whether mortise and tenon or bolted plates of steel, are inherently mechanical. As such, they are wonderful design opportunities that allow us to express our own particular aesthetic, be it all sleek and modern or more rustic and handmade.

Let's look at the basics of post and beam construction, and how to fashion connections that have meaning to you.

Bud Dietrich AIA, original photo on Houzz

While post and beam construction can be used for just about any foundation type, it really does lend itself to a system that relies on piers rather than a continuous footing. This makes sense, as the weight of the house is a series of point loads where the posts are.

Some critical design considerations with these piers include the shape of the pier (square, round or other) as well as how the posts will connect to the piers. While the piers in the sketch here are rectangular, round piers could, depending on the particular soil conditions, be less costly. Just keep in mind that whether or not the pier is seen after the building is completed will be an important determinant of the size and shape of the pier.

Also, prior to construction, you'll want to determine a way to secure the posts to the foundation. Post anchors can be stock or custom and are made of steel. Much of the anchor gets embedded in the concrete to tie the structure together. In this sketch, the anchors are meant to be exposed after the posts are installed. You could, however, use post anchors that would be concealed, embedded in the concrete and hidden within the posts.

Bud Dietrich AIA, original photo on Houzz

This sketch shows a slab-on-grade approach to floor construction. This slab is built much like any other slab on grade, with a layer of crushed rock, a vapor barrier and a layer of rigid insulation all below the actual concrete slab.

An important design consideration with this slab is to know what the floor finish material will be — you'll want to allow for the thickness of that material when setting heights and dimensions for the finished slab and the finished piers. In the sketch the concrete, maybe stained, is the finished floor, so the top of the slab is set flush with the top of the piers. If, on the other hand, the finish were going to be stone or some other thick material, you'd want to set the finished top of slab lower.

Bud Dietrich AIA, original photo on Houzz

Post and beam construction is just that: a system of horizontal beams that transfer structural loads to a system of vertical posts. More traditional post and beam construction also employs a series of diagonal braces that reinforce the beams and help to make the structure rigid.

Post and beam is visually quite distinct. Unlike with a typical wall built of dimensional lumber, post and beam allows for more openness and transparency. This is because the spaces or rooms aren't defined by planar walls but by points.

A post and beam system still relies on a system of walls to help separate inside from outside and room from room. The difference is that none of these walls is structural, so they can be built in any configuration and of any material.

In fact, the walls can be made as screens that can be moved as needed. It's not surprising that post and beam construction, just about the oldest form of building, lends itself to modern open floor plans and contemporary design.

Bud Dietrich AIA, original photo on Houzz

Connecting the Posts and Beams

There are two basic ways of making the connections between the posts and the beams: concealed or exposed.

Concealed connection systems rely on embedding the connectors, whether wood tenons or metal plates, within the thickness of the posts or beams. While mortise and tenon joints were originally fashioned onsite in traditional post and beam construction, stock connectors are now available.

Bud Dietrich AIA, original photo on Houzz

Exposed connectors are surface mounted to the posts and beams and are visually apparent. Traditionally individually forged by ironworkers and smiths, many such connectors are now mass produced and readily available. (In this sketch, the braces have been removed, as the exposed connectors provide the visual interest, and braces might well be structurally unnecessary.)

I'd advise anyone considering exposed connectors to look into having them custom fabricated. These pieces are great visual elements that can really tell your story, so you might not want to rely solely on a generic piece.

G Steuart Gray AIA, original photo on Houzz

Post and beam construction is a great fit for new homes. This type of construction enables large volumes and open floor plans while maintaining a traditional aesthetic and scale. It's an opportunity to have big, open, light-filled spaces that are inspirational and …

 Sand Creek Post & Beam, original photo on Houzz

... comfortable.

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