Pergola bolting patterns and cantilevers explained
When spring time is finally starting to feel real, and the weather starts feeling a bit warmer, it’s hard not to think about spending more time outdoors. Being cooped up in the house in the cold, all winter long, feels terrible and now it will finally start to feel a bit like freedom, just to go back outside and enjoy the fresh air.
A deck or patio is obviously a perfect place to even just sit and have a coffee in the morning or do remote work from home. Pergolas and gazebos, even trellises and awnings, make the outdoor space a little bit nicer. Today we’re looking at pergolas that extend out from the vertical bearing points in cantilevers. Cantilevers are essentially horizontal beams or structural elements that extend away from a vertical load path where there are balconies set away from a structural facade of a building.
The picture below shows the edge of a pergola that juts out away from the vertical post. The edge is tied together with a connection between steel and wood. The unifying steel iron angle at the outside of the tails of the pergola rafters is a 3 in x 3 in angle iron painted back, bolted through to the wood rafter.
In a typical layout, the angle iron, installed here, at the end of the rafters, might be replaced with a single wood element, but in this unique case, the entirety of the structure is tied together with a steel superstructure that really provides the majority of the support.
In the picture above, 7/16 inch stainless steel carriage bolts have been used to connect each of these elements where they join. The carriage bolts are set with the head at the top and the vertical bolts run down through and are connected to sandwich the two joined boards at a washer and nut, at the bottom of the bolt.
Larger bolts are used to join the steel to steel connections. These bolts are one half inch thick and are also connected with hex nuts and relatively small washers, but in the picture below, we can see similar but slightly larger bolts are connected with an entirely different type of washer that’s actually a portion of steel plate. These small plate materials are just a little bit larger than typical washers or fender washers, but they are much thicker and used here to both put the nut in a strong binding position and also distribute the pressure applied between the bottom flange of the I-beam and the steel plate below.
The picture below shows the I-beam connection at the center post. The center post is a 4×4 tube steel and has a plate welded on both sides to connect the suspended c-channel. At each end of the channel, four sets of nuts, bolts, and washers connect the channel to the flange which is welded to the tube steel. The ends of the channels meet together at a relatively thin seam, they almost join seamlessly, but you can see that there is a vertical seam that runs between the flange and the web of the channel.
At the upper beam, which runs perpendicular to the lower support, you can see that there is a vertical wing installed between the flanges of the beam. The vertical support is welded both against the flanges at the top and the bottom and also against the web which runs vertically.
In the several pictures above, this steel support creates a strong framework which can allow for the wooden elements to be set in a firm and solid connecting configuration which allows them to extend away from and beyond the support. The wooden rafters basically run horizontal or at a slight cant or bevel, essentially a slight angle, but near horizontal. The supports below which connect to the footings underground run vertically and the rigidity or stability provided by the steel frame allows that offset in a horizontal direction.
In an upcoming week’s blog article, here on our website, we’re going to look at a few pictures from a similar pergola that extends way out past the vertical area, similar to this configuration, also made with a combination of both steel and wooden elements.
Use a contractor who understands and cares about doing things right. Always, feel free to reach out to us here at Dupont Decks and Patios. We are happy to help with almost all steps of the deck building and design process. A backyard and outdoor space should make a significant, positive impact on both quality of life and home value. We can help with more than just decks, we also build patios, pergolas, ramadas, awnings, gazebos, arbors, and privacy fences.
Let us know about your ideas and talk to us if you have questions about possibilities. We are happy to participate in improving your outdoor space and quality of life! You can call us at (202) 774-9128. You can find us online at https://dupontdeckspatiosdc.com and you can email us there as well at https://dupontdeckspatiosdc.com/contact-us
