Things You'll Need
1-4 foot by 8 foot sheet of 5/8th inch plywood
2-2 by 4’s by 8 foot long
4 foot steel rule
#2 Phillips screw tip
3 inch wood screws
Power miter box
Making the top of an existing garage door opening curved is an easy way to add curb appeal to your home. When you add curves to the corners of a garage door opening, the overhead clearance will be reduced slightly around the area of the corners. If you drive a larger vehicle, you may want to reduce the vertical length of the arched corners to allow your higher vehicle to fit into the garage.
Lay the sheet of 5/8th inch plywood flat on the floor of your garage. At one corner, measure down the four foot side of the plywood 12 inches and place a pencil mark. From the same corner measure 36 inches down the eight foot side of the plywood and place another pencil mark. Set the trammel points 48 inches apart on the steel rule.
Place the steel trammel point on the intersection of the 12-inch mark and the edge of the plywood. Swing the steel rule to create an arc across the plywood. Move the steel trammel point to the intersection of the 36-inch mark and the edge of the plywood. Swing an arc across the plywood. Set the steel trammel point on the intersection of the two arcs. Place the pencil trammel point at the 12-inch mark and the edge of the plywood. Swing the arc over to the 36-inch mark. This will be the curve for your garage door opening.
Measure from one corner and place a mark four feet out on the eight-foot side of the plywood. Repeat the process on the other eight-foot edge of the plywood. Draw a line between the two marks with the four-foot steel rule and the pencil. Cut on the line with the circular saw, splitting the plywood into two four-foot square pieces.
Screw the two pieces of plywood together using two of the three-inch wood screws. Run the screws into the plywood one inch. Place the screws near two opposing corners of the plywood sheets. Make sure that you do not have the screws near the arc that you marked earlier. Use the jigsaw to cut the curve on the plywood. Line-up the straight corner of the cut curved pieces with another square corner of the plywood. Trace the arc onto the plywood with the pencil. Use the jigsaw to cut out the other set of curved pieces.
Cut four pieces of 2 x 4. Make two of the pieces 36 inches long and the other two 10 1/2 inches long. Temporarily screw one 10 1/2-inch and one 36-inch piece together to make an L that measures 36 by 12 inches. Repeat the process with the other two pieces. Stand the L on edge, with the 1 1/2-inch side resting on the floor. Lay a piece of the curve cut plywood onto of the L with the square corners lined-up with the corner of the L. Mark the locations where the arc crosses the 2 x 4 legs. Un-screw the 2 x 4's and cut on the marks with the power miter box set at 45 degrees. Make the 45 degree cut in the same direction as the arc, removing the line. Repeat the process with the other curved corner piece.
Screw the 2 x 4's back together, reforming the 36 inch by 12 inch L. Screw the plywood to both sides of the L, placing a three-inch screw every six inches. Repeat the process to form the other corner. Place a corner in the corner of the garage door opening and screw through the 2 x 4's, into the framing of the garage door opening. Keep the exterior plywood even with the sheathing on the house. Perform the same process on the other corner of the garage door opening.
Cut 20 three-inch long pieces of 2 x 4. Evenly space the pieces in-between the plywood curved pieces. Keep the 1 1/2-inch side of the 2 x 4 even with the edge of the cut curve. Screw each piece into place with two of the three-inch wood screws. Stop installing the pieces when you can no longer fit the 2 x 4 x 3 inch pieces completely in the plywood corner. Cut smaller pieces of 2 x 4 to fit in the plywood until you run flush with the garage opening header.
Cut two pieces of 5/8th inch plywood 4 3/4 by 48 inches. Mark cuts every inch on the cut pieces. Set the depth of your circular saw to 3/8 inch and cut the one-inch lines. This allows you to bend the plywood to cover the opening in the ends of the curved pieces. Miter the edges at 60 degrees on the power miter box. Place one three-inch screw in each of the evenly spaced 2 x 4 x 3 inch pieces to secure the plywood.
Cover the corners to match the exterior finish of your home.