Next » Arbors, sunscreens, patio covers or gazebos, all are designed to keep us comfortably out of the hot sun while we relax with friends and family. Arbors are one of the most appealing and there's a multitude of designs possible. Many of my customers have simply handed me a picture they've cut from a magazine. I'm confident you'll have no trouble getting some ideas.

The size of your column will depend on both size of your structure and amount of weight you plan to set on them. For example, if your going to use 6x6 beams with 2x12 joist and then lay 2x4 slats on top of that, you probably won't be using 4x4 posts to support it. Keep in mind, if you want to enjoy using this structure, having adequate support will not only be more secure it will appear it as well. Using columns not large enough can allow the structure to have excess lateral movement which is not a good thing to see if you happen to be under it on a windy day.

This calculator will help to determine size of framing members and number of columns needed. Setup a batter board and string line around the structure 1/4" out beyond the desired dimensions. This 1/4" clearance is added so columns won't interfere with the string. When setting columns, allow for this 1/4" clearance. If possible, measure from an existing structure or other monumental object like a street curb, fence or concrete retaining wall to setup your first line. This will be your reference line and will not be adjusted again unless both ends are adjusted equally. Arbors are sometimes located over a deck, concrete or right over bare ground. If your building over existing concrete, cutouts will have to be made of a size depending on the size of your vertical columns. 16" square is nominal. A hole, 16" square and 24" deep from the finish grade should be dug into the earth and filled with 6" of concrete to serve as a footer. The end of the column that will sit on this footer should be coated with tar up to three inches above finished grade. Then wrap a layer of clear 4 to 6 mill polyethylene plastic around the tar. Wrap the plastic high enough above finish grade so that later when you trim the bottom of the column with a band of 1x4 or 1x6 you can cut the excess plastic off flush with the top of that point. Both the tar and the plastic will go a long way to give protection from decay especially when using cedar columns. Even pressure treated products made today do not have the insect and decay inhibiting qualities as once was and should be protected.

Drive some stakes into the ground, two at each column and about 4' away or far enough away so you can reach the top of a 2x4x8' brace set at an angle from the stake and extending toward the top of the column. Starting with the corners, set each column on its footer then plumb and brace remembering to allow 1/4" between column and string. Check dimensions near top of columns for proper measurements. Once all corners are set, run a string near the top of each side that has additional columns yet to be set. Allow the same 1/4" clearance as before, then set, plumb and brace these columns measuring for proper distance to center before securing. Expansion block such as cedar 1x4 should be installed next to existing concrete if cutouts were made. A few vertical pieces of 3/8" rebar stakes doweled at an angle into the footer will help for strength if not installed when footer was poured. Some areas may require stirrups as well. Stirrups are a continuous strand of 1/2 rebar, usually three total, around each column and secured to vertical stakes to prevent the concrete from breaking over time. Some rebar suppliers can take care of this fabrication but you can cut short pieces of rebar and secure to your vertical 3/8 rebar stakes then tie the corners if you prefer. Finally, fill the holes with concrete and let setup overnight.

Only use galvanized or stainless steel fasteners with cedar or pressure treated materials. Other fasteners may stain and streak cedar while the copper solution used in pressure treated material is simply not compatible with other fasteners. Ask for compatibility before you purchase bolt, nails, brackets or screws, they are important. Cut top of columns to desired height for head clearance from finish grade to bottom of lowest framing member, usually the beam. Seven foot is nominal however there may be no restrictions or specific code on arbors in your area. Set your supporting members or beams and secure with proper fasteners. Larger heavy members should rest atop columns or set into a notch in the side of the column. Smaller lighter members may lay along the side of the column so long as they are properly secured. Remember, the larger the lumber the more weight, the more weight the larger the supporting members or beams. Set any members above the supporting ones and fasten with proper nails or screws.

I'm a firm believer in wood protection. It is only wood and wood after all is biodegradable. So why not make it last as long as possible? Even if its pressure treated wood it should have one or two initial coats of preserver to seal out water and sun. Your local paint supplier or hardware store can help you with this. As you look at the structure to be sealed you may feel it to be too large a project with all its many edges, corners and hard to reach places. Not to worry if you decide to use a clear or transparent sealer, simply purchase a small pump up garden sprayer. Cover all grass and vegetation before spraying. Re-coat according to sealer manufacturer recommendations.

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