How to Build a Square Gate

Measure between gate posts and subtract 1/2 inch to determine the outer dimensions of your gate. Measure four pieces of 2-by-4 lumber and mark to the width of the gate. Cut the lumber on a miter saw at 45 degrees. The cuts are convergent (not parallel), and the length of the longest side of the cut is equal to the width of the gate.

Lay the lumber on a flat surface and arrange them so they form a frame with 90-degree corners. Measure and cut four pieces of 1-by-6 lumber, with the long sides one-third of the length of the framing members to form the braces. The end cuts are at 45 degrees and convergent.

Lay a brace across a corner of the frame, aligning the edges of the brace to the outer edges of the frame to form a triangle. Attach the brace to one side of the gate frame using a drill, driver bit and a 2-inch screw. Square the corner with a carpenter's square. Affix the brace to the frame with at least two screws through each side of the brace. Square and brace all four corners. Once the braces are attached, insert a 3-inch screw diagonally through each corner to reinforce the corners of the frame.

Turn the braced gate frame over. Measure and cut infill material (pickets, decking or other wood planks) to the height of the gate. For a cohesive appearance, space the infill to match the fence. Measure and mark the positions of the infill planks on the top and bottom of the frame. Align the planks to the marks and affix them to the frame with 2-inch screws.