Remove the rim joists from one side of your gazebo, if it's already assembled. Unscrew the outer joist, and the inner joist if there is one, using an electric screwdriver with a screwdriver bit. Use the joist that is located below the gazebo's doorway opening if you plan to attach the gazebo to your home where an exterior door will open to it directly.
Remove vinyl siding from the side of your home by pulling out the nails that hold its hangers in place using a claw tooth hammer. Remove all siding within 1 foot of the site where you plan to attach the gazebo.
Apply a sheet of adhesive flashing to your home's plywood exterior wall. Omit the previous two steps if your home's walls feature masonry construction.
Drill a series of 1/8-inch holes along the horizontal centerline of your gazebo's floor joist. Place the holes 6 inches apart, and approximately 6 inches from each end of the joist. Drill through both joists at the same time if your gazebo features inner and outer joists.
Place the drilled joists against the side of your home. Measure the distance from the joist to a nearby door sill or remaining row of siding using a tape measure. Repeat this measurement to ensure that the joist is level.
Place a galvanized washer over a 1/2-inch lag bolt. Prepare your impact wrench by attaching it to an air compressor, according to the procedure outlined in the owner's manual
Place the lag bolt's point in one of the 1/8-inch holes along the joist and drive it in with an impact wrench. Continue driving the bolt until its head is firmly against the joist.
Drive in the remaining bolts along the entire length of the joist, using a similar washer on each bolt.
Construct the rest of your gazebo or move a prefabricated gazebo into place and reattach it to the joist that is attached to your home.
Cut the vinyl siding you removed with a utility knife and replace if on your home to surround the gazebo at the point where it attaches. Avoid cutting the adhesive flashing, which will protect your home from water damage at this new vulnerable spot.