This oversize, square trellis adds a modern touch to any space. Vining plants, like mandevilla, love the easy-to-climb supports, and the geometric design looks great while young plants scramble upward.
We built two horizontal panels and one vertical panel to create this large, square trellis. Mix and match panels to create your own eye-catching plant support.
Good to Know: Pressure-treated lumber is likely to have a high-moisture content when first purchased. If your boards feel wet and heavy, set them aside for a week or more so they have time to dry out a little. Stack them with spacers to allow air circulation, and keep them in your garage or shop, or at least out of direct sunlight. If you cut wet lumber and assemble a project with it, the parts are more likely to warp or to crack where fasteners restrict the movement (shrinking) of the wood as it dries.
The key to keeping the project manageable is to build each trellis in two stages. The first stage, shown in the Project Diagram (PDF), involves just the 2 x 2 material (actual dimensions are 1 1/2 inches by 1 1/2 inches).
The second stage adds the 1 x 2 boards (actual dimensions are 3/4 inches by 1 1/2 inches). The joinery remains nearly identical in both stages, with adjustments only in the depth of cut for the 1 x 2 stock. (See the Joinery Detail illustration below for more information.)
For ours, we built two of the horizontal trellises (one installed upside-down) and one of the vertical trellises. You can treat them as modules and build as many as you have room for, in whatever arrangement you like.
Cut the parts
Using the Project Diagram (PDF); Materials and Cut Lists (PDFs) and Pattern Guide (PDF) as references, cut pieces to desired lengths.
All the stock in this project is used in its standard thickness and width, so you're just cutting pieces to length. Label each part with its letter designation and orientation (which face forward, which end up, and so on) to help you stay organized as you work.
Layout marking and cutting the joiner
To ensure that all members fit together properly, mark all joints before you begin cutting or assembling. Refer to the Pattern Guide (PDF). Use a square and a pencil to mark the outer edges of each dado or rabbet you need to cut. If you look closely at the pattern drawings, you'll notice that there's some repetition in the spacing between certain parts or joints. This will reduce the setup time if you're using stop blocks or your table saw's rip fence as an index stop while you're cutting.
Even a dado blade will require multiple passes for each dado and rabbet, and in some cases it may be faster just to use your standard saw blade and make more cuts. You can leave some narrow waste portions (less than 1/4 inch wide) intact between the outer cuts and then clean them out with a wood chisel.
As you work, try some occasional test-fits to see how the parts are fitting together. The dadoes and rabbets should form half-lap joints where the parts intersect. Cut all of the joints, including the stage two parts, before assembling any of the trellis. Also, pick out the parts that will form the back of the lap joints, then drill countersunk 3/16-inch holes for screws as shown.
Assembly and finishing touches
When you're ready to put the trellis together, start with the perimeter stiles (A) and rails (B). Overlap the corner joints and fasten them with 1-1/4-inch screws. Don't bother with glue on these and other joints that you're securing with screws; it's not really necessary, and this method allows you to loosen joints to help other parts fit in place.
Continue working your way through the parts in alphabetical order, fastening as you go. The 1 x 2 parts for stage two can also be attached with screws, but just where they meet the 2 x 2 stock; anywhere they meet another 1 x 2 in a half-lap joint, glue and clamp the connection.
Check that all screw heads are flush with the surface, and then use a sanding block to ease any sharp edges or corners. Finish the trellis according to your preference. We opted for a solid-color exterior stain.
Methods for hanging the trellis will vary according to the wall surface, though all installations should leave a gap between the trellis and the siding. We cut some small stand-off blocks and used them as spacers for our installation. Fastener length and type will also vary according to the wall surface. Deck-type exterior screws will work fine in wood or engineered wood siding, but brick, stucco or other masonry surfaces will require the use of expansion anchors.