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One of the first things you may notice about an old gate is its sag. In fact, sag is likely the only thing that makes the gate seem old if the wood is in good condition and the mechanism works.

Gate sag is an unfortunate and unsightly problem for many homeowners. It can turn even the most welcoming, beautiful front entrance into something more along the lines of a Halloween haunted house.

In order to prevent gate sag, it’s important to understand why it happens in the first place.

Gate Building 101: Why Old Gates Sag

At their simplest, gates are inherently unstable structures. One end is fixed to a post, usually using three hinges, while the other is free to swing open and closed. This means that the weight of the free end of the gate will always be pulling against its post, hinges, screws, latches, etc.

In general, there are only a few reasons why a gate would sag. Either the gate material is warped, its hinges are not correctly in place, the gate is lacking structure components or its posts are no longer parallel with one another.

There are multiple cases where this effect will be exaggerated:

• Wooden gates tend to sag more often than metal gates, although both can sag for different reasons.
• Gates made of low-quality wood will sag more readily once exposed to moisture. The effect of moisture will push the wood out of shape, increasing sag.
• Posts that are not sunk low enough into the ground may eventually succumb to the weight of the gate.
• The gateways built without diagonal gate structural bracing.

Fortunately, there are ways to protect yourself against the possibility of gate sag.

How to Prevent Sag for an Outdoor Gate

To keep a gate from sagging, you first must determine where the problem is. In most cases, either the gate’s wooden frame is sagging under its own weight, or the posts are no longer parallel.

If the frame sags, a diagonal brace can help. High school geometry teaches that squares and rectangles are not as strong and solid as triangles. The easiest way to reinforce a gate is to attach a diagonal brace or tension rod connecting one of the hinges to the corner opposite.

This equalizes the tension between each side of the gate. But it will only be as powerful as the primary joint itself.

If the posts themselves are not parallel, then you will need to reinforce them. This could mean digging them up, pouring concrete, and fastening them to a more stable foundation. As well as, using a longer post so that a “brace” or “arbour” can be built overhead to keep the posts and the opening square and parallel. Yielding an opening that is straighter, truer, for longer.