Wind Load on Ornamental Ironwork

Hurricane season turns a driveway gate into a structure with a wind rating, whether or not anybody calculated one. The storm preparation list held at Pearland Iron Gates, TX Elizabethbaron assumes a leaf will be hit while open, because on iron gates in Pearland that is the position most of them are left in when people leave.

Area Is the Whole Story

Force on the leaf rises with the area presented to the wind and with the square of the wind speed. An open picket panel presents very little. A backed or solid leaf presents nearly all of its face, and doubling the wind speed quadruples what the hinge and the post have to hold.

The Open Position

A swing gate standing open is a cantilever with nothing at its free end. A gust hits it side on and the whole load goes into the hinge, and then into the post and its concrete footing. That is where hinges tear out and posts lean, rather than in the closed position where a catch or a latch takes some of it.

Holding It Still

A drop rod into a ground socket at the open position, and a second socket at the closed position, is the simplest answer and costs almost nothing. Gate stops and a positive latch do the rest. An automated leaf held only by its operator relies on a gearbox to resist the wind, and that is not what a gearbox is for.

Before a Named Storm

Close the leaves, latch them, and pin them if a drop rod is fitted. Release the operator so a power surge cannot drive against a pinned gate. Clear anything from the driveway that could be thrown into the panel, and check the catch is engaged rather than merely resting.

Afterwards

Check each post for plumb, each hinge for movement in its fixing, and the alignment of the two leaves against each other at the meeting point. A gate that closes but no longer meets cleanly has usually moved at a footing, and finding that early is much cheaper than discovering it when the latch stops reaching.