Preprinted plans are available in how-to publications from home improvement stores and Internet sites, or you can design your own. You will need to decide if the backrest will adjust and if the lounge itself will be movable. The simplest style has straight lines with a frame and slats (Reference 2). Although functional, these don't provide as much comfort as a contoured lounge unless you plan to use a chaise cushion. Also, choose your wood. Redwood, white oak or teak will hold up well in the outdoors. You will need a circular saw, drill and bits, router and measuring device.
Now that you have a plan from which to work, gather the lumber and supplies. The lounge will need to be about 6 feet long and 2 feet wide but can be wider if you wish. Five 10-foot-long 2-by-4-inch and one 8-foot-long 2-by-4-inch lumber pieces will be enough. Decking screws in 3-inch (80), 2 1/2-inch (8) and 1 1/2-inch (12) lengths, a pair of 7-inch-diameter rubber tire wheels (lawn mower wheels), a 1/2-inch diameter steel rod, one pair of cog-latch braces, four 1/2-inch flat washers, two cotter pins and two strap hinges should do the job. The cog-latch braces allow the backrest to ratchet up and down.
Cut two 72-inch-long side rails and 11 21-inch-long seat slats from the 10-foot 2-by-4s. Rout all the sharp edges. Join the end slat to the side rails using the 3-inch screws. Next, join the hinge slat to the side rails. The hinge slat is the one where the adjustable backrest attaches to the side rails. Measure 44 inches from the end of side rails for its placement. Turn the frame on its side. Take a flexible strip of thin plywood or laminate, and curve it along the side rail until you get a contour you like. Trace the curve onto the side rail. Measure several distances along the curve so that you can repeat the same curve on the other side of the frame. Fasten the slats long this curved line with the 3-inch deck screws.
Cut the back legs 12 1/2 inches long and the front legs 14 inches long the remaining material from the 10-foot 2-by-4s. Rout the sharp edges. Attach the front legs to the main frame with the 2 1/2-inch screws. They attach to the outside of the side rail. Make sure they are perpendicular to the sides. Assemble the wheel using the axle, cotter pins, washers and wheels, and install it into the back legs. Cut a 24-inch back stop from the 8-foot 2-by-4s, and install it above the wheel assembly between the legs. Now attach the back legs to the side rails.
Cut two 28-inch-long rails and seven 17 3/4-inch-long slats for the backrest portion of the chaise. Rout the sharp edges. Contour it in the same manner as you did the seat portion and attach the slats accordingly. Center the backrest over the main frame. Install the cog-brace hinges making sure to align them perfectly with each other. They will work together to allow the backrest to lie flat and to raise and lower.
Sand the lounge, being careful to smooth any splintery areas. Give your chaise a coat or two of clear sealer, and allow to dry.