For our new horse riding arena we chose to build a full perimeter fence. This will be consisting of wood posts and boards that would match our out buildings and horse sheds. We used 8 inch posts, and 2 x 6 boards 16 feet long. Our posts were spaced 8 feet apart, this enabled us to fasten each 2 x 6 board to three posts. This was to reduce the chance of the 2 x 6 boards warping and twisting, as well as making the fence stronger. The position of all the posts, including gateways were staked out prior to constructing the arena fence. Our arena will be 200 x 100 feet, with a 12 foot gate at each end. We began by tying a string to a corner stake and pulling it 200 feet to the next corner stake on the long side of the arena. After pulling the string tight to ensure that it was a perfectly straight-line, we tied it tightly to the second stake. A stake for each post was then placed along the string line at 8 foot intervals to complete the first side of our perimeter fence.
To layout the second side of our riding arena fence we measured 100 feet from the corner stake and put a stake in the ground for the next corner. To make sure that the corners are perfect 90° angles. We could have used a construction calculator to do the math. Instead we made our own 90 degree angle with, a known math solution, the old tried and tested method of the 3, 4, 5 right-triangle solution. A triangle that has three sides where one is 3 feet long, another is 4 feet and the third leg is 5 feet long creates a right triangle. The intersection of the 3 foot and 4 foot leg create a perfect 90 degree angle. Any multiples of these dimensions also work; 6, 8, 10 or 12, 16, and 20 are also combinations that yield a perfect 90 degree angle. To make our corner, we used a measurement of 100 feet to the next corner, 75 feet back down our staked fence line, and 125 feet for our diagonal measurement. Where the 100 foot measurement, and the 125 foot measurement intersected we placed our next corner stake. After pulling a string to make sure of a straight-line, we placed 11 stakes at 8 foot intervals along the string. This made a total distance of 88 feet. The remaining 12 feet is where our gate went. We chose to use a 12 foot gate at each end of our arena for two reasons. First this is a good-sized opening for getting machinery into the arena to maintain the riding surface. And secondly, 12 feet gave us an even measurement for our 8 foot post spacing on the 100 foot side of the arena.
To layout and stake the third side of our arena perimeter fence, we measured 200 feet and placed the last corner stake, taking care to have perfect 90° angles on our corners using the 3, 4, 5 right-triangle solution. After pulling a straight string line we placed our post stakes every 8 feet completing the layout of the third side. We laid out the last side of the arena with 11 stakes spaced 8 feet apart for the posts and another 12 foot opening for a gate.
After all of the perimeter post positions had been staked, we used a post hole digger on a machine to drill the holes in the ground for our posts. Our posts were 8 feet long, and our holes were drilled 2 feet deep, so that we would have 6 feet of post sticking out of the ground when finished. We used a string line and level to make sure all of our posts were straight and uniform before tamping and watering the ground around them for compaction.
When all of the perimeter posts had been tamped into place, we then began fastening our 2 x 6 boards to the posts for the railings. We chose to use two railings one at 30 inches to the top, and another at 60 inches to the top of railing. Before fastening the railings to the posts, we pulled a string line tightly down the row of posts at 30 inches high and made a mark on each post were the top of the bottom railing will be, we also made another mark at 60 inches for the top of the top rail. Next we used clamps to clamp our 2 x 6 railing to the posts taking care to line up with our mark, we had made previously. The railings will be attached to the posts using 5/16 by 3 inch long lag bolts with a large flat washer. To do this, we first drilled two holes slightly smaller than 5/16 through the railing and into the post. We chose to use two bolts to fasten our railings to each post, therefore the two bolt holes were drilled in the railings 1 1/2 inches from the edge of the 2 x 6. We did not want our bolt heads to protrude out of the railing, so we drilled the two holes in the railing slightly larger than the washer 1/2″ deep to countersink the washer and head of the lag bolt. After inserting the bolts into the holes and tightening them up, the clamps were then removed and the process was repeated for the next railing.
After attaching all of the railings to the posts, we then hung the two 12 foot gates on each end of our riding arena. We purchased two steel gate kits that came with hinges and a latch on them ready for installation. To hang the gates was a simple matter of drilling two holes through the gateposts at the correct height. The final step to completing our riding arena was to paint all of the wood railings and posts with a good outdoor protective paint that would preserve and protect the wood, as well as matching the color on our existing horse sheds.