Q–I would like to construct a simple, yet elegant wood trellis for my garden. What is involved in this project? What wood will yield long life and minimal maintenance? Can an average homeowner successfully complete this project?
A–Have you have been talking to my wife, Kathy? I am getting ready to build her a series of trellises for our gardens and patio.
A trellis can add a unique flair to a deck, patio or even a front porch. It makes an excellent sun-filtering screen that creates delightful shadow patterns.
Trellis structures can range from simple to complex. The most basic can be built by assembling three ladder-type structures. Two of the ladder sections simply stick vertically from the ground. The third section spans between the two to form the overhead portion of the trellis. The flat “rungs” of each ladder allow your vines and ivy to extend into and over the structure.
A multitiered, partially roofed or pagoda-styled trellis can be built as well. These complex styles may challenge a novice do-it-yourselfer.
Start with a simple design for your first project. For example, you might use two vertical sections that project 7 feet from the ground. The overhead portion can be 8 feet long. All three sections can be about 16 to 18 inches wide. If the vertical sections are spaced 5 feet apart, the top section will overhang each end by 18 inches. This makes for a graceful, cantilevered design.
I intend to construct a bench between the two vertical standards. This will give Kathy an excellent vantage point to view the hummingbirds that visit our patio feeders.
I prefer to use redwood or western red cedar for these outdoor projects. Both of these woods contain natural preservative chemicals, which not only slow wood rot but also discourage wood-destroying insects, which find them distasteful. Both wood species are available in a variety of grades. I intend to use construction heart grade and construction common grade for my trellis. The construction heart grade contains some very tight knots. Because it is heartwood, it has a high natural chemical content. This makes it perfect for the posts that will be buried in the soil. I will use the construction common grade lumber for all of the small cross members and above-ground support beams.
The trick for easy installation lies in constructing the trellis in your garage or basement. It is very difficult to build the trellis in place. To minimize maintenance, you need to coat the wood with a clear or pigmented synthetic resin water repellent or paint before you start to cut or fit the lumber. This inhibits water from entering the wood where two pieces overlap. Be sure to coat exposed end grain as you cut and trim the pieces. Stainless steel nails, screws and bolts are the best fasteners to use. If these aren’t available, then select the highest quality hot-dipped galvanized fasteners you can find.
Construct the two ladder sections first. Make sure you let the bottom portions of the posts run an extra 2 feet or so. This will allow you to bury the posts in the ground at least 16 inches and leave you an extra 8 inches of length to make adjustments for sloping ground conditions within your garden. It is important that the top of the two sections are level once installed. If they aren’t, the top horizontal section will slope.
Dig post holes that are slightly larger than the posts and put 2 inches of washed gravel in the bottom. After placing the posts in the holes, put in additional washed gravel, rather than soil, around the posts. Using gravel will extend the life of the posts. Moist soil that comes into direct contact with wood promotes wood rot. Top off the washed gravel with 4 inches of crushed gravel. This will lock the post tightly in place.
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Have questions about the remodeling process? Write to Tim Carter, c/o The Chicago Tribune, P.O. Box 36352, Cincinnati, Ohio 45236-0352. Questions will be answered only in the column.
Ask for Builder Bulletin No. 186. For a list of sources of redwood trellis designs, wood grade specifications, plans and other tips on building garden and patio trellises, send $2 and your name and address to Tim Carter at the above address.
For a wide variety of individual job bid sheets and for a list of past Builder Bulletins, send a business-size, stamped, self-addressed to the same address.
Ask the Contractor can also be accessed via the Internet at http://www.chicago.tribune.com/homes/articles/askcon.
