How to Make a Roof on Your Deck

Measure the height of the deck from the ground using a tape measure. Add 8-1/2 feet to this measurement to determine the length of the roof support posts. Cut four 2-by-4 timbers to this length using a circular saw. Measure the width of the deck and add 8 inches to this measurement. Cut two sheets of 1/2 inch thick plywood to this measurement in length and 4 inches in width.

Measure the length of the deck and add 4 inches. Cut two pieces of 1/2 inch thick plywood to this measurement in length and 4 inches in width. Screw the deck width and deck length plywood sheets together to form a rectangle that stands 4 inches tall, using L-brackets on the outside of the rectangle for the joints.

Cut a sheet of plywood to a length equal to the width of the deck, plus 7 inches. Screw this sheet into the middle of the rectangle using L-brackets as a cross support joist. Divide the width of the deck into thirds and the length of the deck in half. Cut six sheets of 1/2 inch thick plywood to these measurements. Screw the sheets to the top of the rectangle to form the deck roof.

Varnish the deck roof and the four support posts using exterior grade varnish and a paintbrush. While the varnish is drying, dig a 1 foot deep hole at each corner of the deck using a shovel. Prepare a batch of concrete from one part cement, two parts sand and one part water. Insert one support post in each hole. Fill the holes with concrete up to ground level. Wait 48 hours for the concrete to set.

Set two step ladders on the deck, one by a front support post and the other by the opposite rear support post. Raise the deck roof onto the top of the support posts, with the help of an assistant, so the edges of the roof sit around the support posts. Screw the roof to the support posts with L-brackets.