Many of my company’s deck and porch jobs include an arbor or two. Arbors are popular because they’re functional as well as attractive and can be customized to fit just about any outdoor space. They can be used, for instance, to cast partial shade on a sunny section of a deck. Planting vines to climb on them can offer even more protection from the sun.

Arbors also serve a number of design needs. An arbor in the middle or at the edge of a deck forms an outdoor room that entices people to walk toward its sheltering shade and protective cover, whereas an arbor installed out in the yard creates a focal point in the landscape, drawing visitors’ eyes toward it.

We build our arbors on site, usually assembling them one stick at a time in place. If the arbor is small, we might fabricate the whole structure before lifting it into position. All the arbors we build share the same basic structural components: columns (or posts), cross beams, joists, and cross-lathing.

The smallest column we’ll use is a 6x6—anything smaller is prone to bowing and looks undersized. Cross-beam and joist sizes vary depending on the length and width of the arbor, but even on a small arbor, a 2x8 cross beam would be the smallest we’d use

As a general rule, we size the joists as we would for low-slope roof rafters of a similar length. For a small arbor with 2x8 cross beams, we use 2x6 joists. If the cross beams are 2x10s or 2x12s, we use 2x8s or 2x10s for joists. Deck design and spans affect column counts and spacing. If necessary, we’ll upsize the beams to increase the span 

A version of this article originally appeared in our sister publication, Professional Deck Builder.