Tips for Building Arbors

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1. Main Attraction   Installing an arbor on the edge o… Read More 1. Main Attraction   Installing an arbor on the edge of a deck will draw visitors to its shade and shelter, and keep them from congregating in front of the doorways. Alternatively, placing an arbor  at the entryway emphasizes the stairway and conveys a sense of welcome.

2. Shade Spacing An arbor’s topmost lath pieces, milled from r… Read More 2. Shade Spacing An arbor’s topmost lath pieces, milled from ripped 2x4s and installed on 6-inch centers, cast partial shade on a deck. The lath also contributes to the arbor’s strength and helps restrain the joists. To prevent bowing and twisting at their ends, lath pieces should extend no more than 4 to 5 inches beyond the edges of the outermost joists.

3. Beams and Overhangs A general rule for the length of an overh… Read More 3. Beams and Overhangs A general rule for the length of an overhang on an arbor is to double the nominal width of the lumber. For instance, a 2×8 joist should extend 16 inches beyond the beam  it rests on. Bolting two cross beams together and attaching them to one side of a column can look too massive and heavy, so it’s usually best to flank the column with one beam on each side, for a lighter, more delicate look. 

4. Standing Alone A freestanding arbor gains extra support from … Read More 4. Standing Alone A freestanding arbor gains extra support from its attachments to railings and adjacent framing. A stand-alone arbor that can’t be tied to a deck’s framing—such as one in a backyard—can be set in gravel- or concrete-filled postholes extending below the local frost line.

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 6×6—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 2×8 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 2×8 cross beams, we use 2×6 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.