18x18 Pergola Kits

18x18 Refers to the Size of the Pergola's Roof

All of the pergolas featured on this page have an 18' x 18' pergola roof covered by shade purlins, not including the end caps on traditional-style pergolas (which extend 9 inches beyond  the ends of the 18' beams and the 18' rafters, unless you opt for flat end caps). So for all of the 18-foot by 18-foot pergolas on this page, all roof components (including beams, rafters, purlin holders and shade purlins) are 18 feet long, not including end caps.

Post Placement for 18x18 Pergolas

The posts (i.e. columns) of a traditional 18' x 18' pergola can be placed anywhere from 0" to 36" in from the outside edges of the beams and rafters (not including the 9" end caps), as shown in this diagram. Most customers choose to place the posts 12 inches in from the ends of the beams/rafters as shown in this CAD drawing, which puts the outside edges of the posts 16 feet apart both width-wise and depth-wise. But again, you can position the posts anywhere from 0 to 36 inches in from the ends of the beams/rafters to create your desired overhangs. It's also worth noting that the overhang can be different on one side than it is on the other sides, if needed or desired.

For modern-style 18x18 pergolas (which never have overhangs), the posts are always in the corners. So for modern pergolas, the outside edges of the posts will be 18 feet apart width-wise and depth-wise.

All Parts Can Be Trimmed Down to Your Desired Length

To make our pergolas as affordable as possible, we only manufacture the beams, rafters, purlin holders and shade purlins in 2-foot increments. But one or both of the width/depth dimensions of your deck, patio or other outdoor space may be slightly shorter than 18 feet by 18 feet. Using a basic circular saw or miter saw, you can cut any of the pieces down to the exact length required. Thus, the 18x18 pergolas on this page can easily be turned into 17.625-foot by 17.75-foot pergolas (or whatever specific dimensions you need).