Arched Tops and the Ground Beneath

An arch reads as a single line from the street, so any error in it is obvious in a way a straight rail forgives. The setting out method used at Pearland Iron Gates, TX Elizabethbaron draws the curve against the real driveway rather than on paper, because iron gates in Pearland sit on ground that rarely runs level across an opening.

Arched, Rising and Level

An arched pair curves up to the meeting point in the middle and back down at the posts. A rising pair keeps the top rail straight but climbs across the opening to follow a slope. A level pair does neither. Mixing the ideas produces a gate that looks like it was drawn for a different house.

The Ground Decides the Bottom

The bottom rail has to keep a consistent clearance over ground that is often not flat. On a cross fall the bottom is stepped or raked to follow it, and the top can then be arched independently. Trying to keep both rails parallel on sloping ground is what produces a large gap at one post.

Drawing the Arc

A string from a centre point below the gate, or three points measured on site and a batten sprung through them. The rise is usually a small fraction of the width, and a rise that is too generous makes the leaf look heavy at the middle. Standing back at the distance a visitor sees it from is the check that matters.

Fabricating the Curve

The top rail is rolled rather than cut from plate, so the section keeps its strength around the curve. Each picket is then cut to a different length and the top of every one meets the rail at a slightly different angle. That is why an arched leaf costs more than a straight one of the same size.

What It Does to Clearance

An arched top gives extra height at the middle for a delivery truck without raising the whole leaf. On a swing gate the arc also has to clear the ground through its full sweep, so the rise at the outer edge is checked with the gate at its widest opening, not just closed.