Brace a Gate Frame in Compression — From the Top Outside Corner Down to the Hinge

The Problem

Wooden gates sag. The frame is a rectangle, a rectangle racks, and every swing works the far corner downward until the latch drags. A diagonal brace fixes it — but only if it runs the right way, and half the videos online show it installed backwards, where it does almost nothing.

The Technique

Marking the cut:

1. Lay the brace stock diagonally underneath the assembled gate frame, overlapping both frame members at each end of the diagonal.
2. Position it so most of the overlap lands on the bottom rail at the low end and on the top rail at the high end, then trace the frame's edges onto the brace from above.
3. Cut the traced lines with a circular saw — the brace now drops into the frame with matched angles at both ends.

The direction that matters:

4. Install the brace running from the top corner on the latch side down to the bottom corner on the hinge side. This puts the brace in compression: the weight of the gate's far corner pushes down the diagonal, into the bottom hinge, and through it into the post.
5. Wood is far stronger being squeezed than being stretched — a compression brace bears the load as a strut, while the same board run the other way has to work as a tension tie held only by its fasteners, and the fasteners creep.