Home / Gate Posts for Heavy Pipe Gates

Gate Posts for Heavy Pipe Gates

By metal gates cedar park journal

The post is the part of a heavy gate that nobody photographs and everybody eventually regrets skimping on. A pipe gate may weigh a few hundred pounds, and every pound is carried by a post and the ground around it. When a post leans, the gate sags, the latch misses and the hinge hardware is blamed for a problem that started below the surface. This page covers how posts are sized, how deep they go, how concrete helps, and how rock and clay change the plan.

What the post is asked to do

A hinge post resists two things at once. It supports the vertical weight of the leaf, and it resists a sideways pull that tries to tip it toward the gate every time the leaf swings open. The sideways pull is the harder job. A leaf twelve feet long is a lever, and the post sits at the short end of that lever, so the force at the top hinge can be many times the weight of the gate itself.

The latch post has an easier life, since it mostly receives the closing impact and the occasional lean of an animal. Even so, many installers make it the same size as the hinge post for appearance and to handle that abuse.

Choosing the post size

Heavy pipe gates usually hang from posts with an outside diameter well above that of the rails, commonly four to six inches or more for large gates, with a wall thick enough to resist denting and local buckling. A thicker wall adds strength at the point where the hinge bolts or welds through. A thin walled large pipe can look impressive but still flex under load.

As a general principle, the longer and heavier the leaf, the larger and thicker the post. A fabricator who knows the leaf weight can match the post size to it. A common mistake is reusing a fence post, which is designed for light line tension rather than a swinging load, as a gate post.

How deep and how wide

Depth does most of the work. A rule often quoted for fence and gate posts is to bury at least a third of the post's total length, with heavier gates going deeper. A post that stands five feet above ground might therefore be set three feet or more below it, and larger gates call for more. Depth gives the footing leverage against tipping.

The hole width matters too. A wider bell of concrete resists tilt better than a narrow shaft. The hole should be several times the diameter of the post, so there is a thick collar of concrete all around. Skimping on width produces a post that is deep but still loose, because the thin collar flexes in the soil.

Concrete and how to place it

Concrete locks the post to the ground and spreads the load across a larger area. The mix should be firm, not soupy, and it should be tamped or vibrated around the pipe to fill voids. The concrete should rise to just above ground level and be sloped away from the post so rainwater drains outward, not toward the pipe.

Give the concrete time to cure before hanging the leaf. Hanging a heavy gate on fresh concrete invites movement while the mix is still weak. A few days of patience is cheap compared with resetting a post that settled out of plumb.

Setting posts in limestone

Williamson County sits over limestone, and shallow rock is common. When rock comes up close to the surface, an auger may refuse to go deeper. The choices are to drill the rock with a rock bit, to chip a socket, or to anchor the post in a shallower hole with steel pins and extra concrete. Drilled sockets give the best result, because the pipe sits in solid rock with a grout or concrete fill around it.

Always test the fit before pouring. A post that must tilt to clear a rock ledge cannot be plumb. Test the hole dry, adjust, and only then place concrete. Drainage at the base also matters, since water trapped at the bottom of a rock socket can freeze or corrode the pipe over time.

Setting posts in clay

Clay behaves very differently. It swells when wet and shrinks when dry, and that movement pushes and pulls on a post. A post in expansive clay can lean slowly over several seasons even when set correctly. Deeper holes help, because deeper clay holds more steady moisture, and so does a bell shaped base that resists lifting.

Some installers wrap the upper portion of the post in a sleeve or use a tapered hole so the clay cannot grip the pipe and heave it. Grading the ground to shed water away from the post also reduces swings in soil moisture. These measures cost little compared with replacing a post.

Corner and brace posts

People sorting out a heavy entry frequently read more at metal gates cedar park journal to see how the posts, leaf and fence line fit together.

Where a gate meets a corner of the fence, or where tension from a long run of wire pulls on the post, extra bracing is added. A brace post set several feet from the main post, joined by a horizontal member and a diagonal, spreads the load. An H brace is the classic form. It lets a lighter post work in a heavy duty position, but it needs space and added labor.

For gate posts in a fence line, make sure the fence tension is not pulling the post toward the fence side while the gate pulls it the other way. Two forces that cancel at rest can combine at a bad moment, such as when the gate is thrown open.

Checking and correcting a leaning post

Use a level, or even a plumb line, to check a post against vertical on two sides. A lean of more than a small fraction of an inch over the post height is worth attention. Early correction can mean digging beside the post, resetting concrete, or adding a brace. Waiting until the lean is large usually means pulling the post and starting over.

Watch the gap between the latch and the strike. If the gap is closing from one season to the next, the hinge post is probably moving. Watch the top of the post as well, since movement shows up there first.

A sensible order of operations

• Choose the leaf weight and width before sizing the post.
• Locate buried lines and test the ground for rock.
• Dig or drill to the planned depth with a generous width.
• Set the pipe plumb and brace it temporarily.
• Place and tamp the concrete, sloping the top away from the pipe.
• Wait for full cure before hanging the leaf.

Treat the post as the foundation of the gate, because that is exactly what it is. A well set post makes everything attached to it work better, and a poorly set one makes even a beautifully built leaf fail.