DIY Adjustable Livestock Gate

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By Staff | Dec 4, 2018


DIY Adjustable Livestock Gate 

Build an extendable livestock gate to make your routine with your livestock a little easier.

By Karen McGeorge Sanders and D.T. Sanders

January/February 2019


Moving livestock from one pasture to another should be a quick, efficient operation with no chance of animals escaping, no risk of injury, and no liability worries. That’s easy enough, except when you’re crossing a road. Wouldn’t it be nice to create a safe corridor for a livestock crossing?

Our acreage is completely fenced, with gates connecting one pasture to the next, except for a small pasture that feeds into the horse stalls. This small pasture is separated from the rest of the fields by our gated driveway, and we needed to find a way to connect them.

We already had a gate on one side of the driveway, but it was too long to fully swing open and create a passageway, because it would be blocked by the smaller pasture gate on the opposite side of the driveway.

The solution was to build a gate that changed lengths, so it could act as a gate when closed and one side of a passageway when open. We worked out a way to build this with two gates of different lengths, some U bolts, a wheel, and a little welding. To build an extendable gate of your own, you can follow these directions and adjust them for your own needs.

1. Define Your Necessary Gate Length

Measure the distance of the gate opening (G). Then, measure the distance of the space you’ll need to span to create a passageway for your livestock (P). On our property, the gate opening (G) is 20 feet and the space we needed to close (P) is 18 feet

The problem is (G) is too long to fit across our driveway (P).


Next, purchase a pair of gates. Metal-pipe gates are sold in standard lengths of 6, 8, 12, and 16 feet. We purchased two gates: one that was 6 feet long and another that was 16 feet long. The shorter gate needs to slide on the longer gate to maintain the structural integrity of the whole when the gate is in the extended position.


Note: When choosing gate lengths, remember that the shorter gate should only extend to a maximum of half its length, so that its weight stays well-distributed and the gate doesn’t tilt or sag when extended.


2. Determine Where to Connect the Gates

Find the balance point on the shorter gate, which will be halfway across its length. On a 6-foot gate, the balance point will be at 3 feet. The balance point shouldn’t slide past the end of the longer gate.


Measure halfway between the balance point and the end of the shorter gate. On a 6-foot gate, this would be 1½ feet from the end. This is the location for the first U bolt that will go around the shorter gate and attach to the longer gate.


The balance point of the shorter gate will be another U bolt attachment point. The U bolt will go around the shorter gate and attach to the longer gate.


The last U bolt will go around the longer gate and attach to the shorter gate. This is at the end of the shorter gate to prevent it from moving away from the longer gate.


Attach U bolts on the bottom of the gate in the same way as the top.

Note: If your extendable gate is longer than 6 feet, you’ll need to add more U bolts. Space them evenly between the balance point and the end of the gate.

3. Connect the Gates to Each Other

You can connect the gates using either a welded or a nonwelded method, depending on the tools and skills available to you. Welding is the preferred method because the U bolts won’t slide out of place as you adjust the gate length, but a secure attachment can be accomplished with the nonwelded method as well.

Welding Method: With this method, the U bolts are welded to their respective gates and cannot move out of position; this allows you to expand the gate without making adjustments to the U bolts.

a. Clamp the gates together so they can’t move with respect to each other.

b. Position the U bolts with the flat plate installed between the gates.

c. Adjust the nuts to allow space for movement of the shorter gate.

d. Use another clamp to bend the ends of the bolts toward each other and around the gate they’ll be welded to.

e. Using all appropriate safety precautions and equipment, weld the threaded portion of the bolts to the gate, both top and bottom.

Nonwelding Method: You can also attach the gates using two flat plates per bolt, anchoring the flat plates to the gates by drilling a center hole for another screw and bolt. This method will require 6 additional flat plates, along with 12 additional nuts.

a. Clamp the gates together with a flat plate between them.

b. Position the U bolts with the threaded ends to the non-moving gate and the nuts installed on the moving-gate side of the bolt.

c. Put on another flat plate at the end of each U bolt and install an additional set of nuts.

d. Tighten the nuts, pinching the non-moving gate between them.

e. At this point, check that the shorter gate will still slide.

f. Using an electric drill, install a self-tapping screw in each plate. This step will help to keep the U bolts in their respective positions when you’re operating the adjustable gate.

Note: The bolts will require monitoring for loosening and tightening as needed.

4. Mount the Gate Assembly to a Post

Our gate is mounted to a 6-by-6-inch gate post that’s set in the ground with 300 pounds of concrete. We used three gate hangers to evenly distribute the weight across the post from top to bottom.

The extendable gate will weigh more than a single gate due to the extra weight at the end. Take this into consideration when choosing a post to mount it to. The post should be solid and heavy; you may need to install a new post if your pre-existing one isn’t up to the task.

5. Install a Wheel

You can pull or push the gate along the U bolts to extend or retract it as needed to span the passageway. To prevent the gate from scraping the ground when extended, and to make it easier to move, you should install a gate wheel at the end of the shorter gate.

Designed as a quick solution for moving horses, our extendable gate has kept our animals safe for more than 20 years, with the only care necessary being an occasional spray of WD-40. 

Karen McGeorge Sanders has published over 200 articles and is currently working on a children’s book. D.T. Sanders is an aerospace systems engineer and author who built a 5-acre equine estate in Washington. The couple lives in Montana.

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