Squaring a pole barn enhances its appearance and ensures that it will be of the desired size after completion. It also adds stability after the construction is complete, making storing anything inside a much safer proposition.The following instructions will work with virtually any sized pole barn, starting from the ground up.
Drive a stake in the ground with a hammer where you intend to start building. This will be your cornerstone reference point. Measure and cut two lengths of string to the measured length of your pole barn. Place a mark or a piece of tape 6 inches in from both ends of the strings. Tie the strings to your stake so that the mark or the tape is flush with the stake. Decide what direction you want the barn to extend from that point, and stretch your string in perpendicular directions from your starting point.
Square the first corner. For best results, use a carpenters square to attach two 3-foot sections of 2x4 lumber at a 90 degree angle. Attach stakes to the outside edge of the 2x4's and place the stakes in ground so that the inside corner of the 2x4's are touching your cornerstone stake. Orient the arms to point in the rough direction that your strings are going.
Square the second corner. Tie the end of one of your stings to another stake so that the mark or tape is flush with that stake. Extend the string until it is taut and runs parallel or flush to the 2x4 corner that you have built around the first stake. When both of these conditions are met, place the stake in the ground. Then build a second 2x4 corner using your carpenters square and make sure that it also has a 90 degree angle. Attach stakes to it and place it so that the side pointing towards your first stake is perfectly flush with the string, and the other arm points, 90 degrees away.
Square the third corner. Follow the steps from above to set a stake and 2x4 apparatus to the other loose section of string. Measure and cut two more pieces of string to the measurement of the pole barn, and place marks or tape 6' inches in from each end. Tie them to the second and third stakes so that the mark or tape is flush with the stake, and extend them 90 degrees away from the other line.
Square the fourth corner. The two measures of string should meet up at a point where the mark or tape section overlaps. Just to be sure, attach a stake to one string first and square in the same way that you did in the previous steps. Once your stake has been set, extend the last loose section of string to the stake. If the mark or tape in the string matches extends right to the stake, and the string is flush with both of the 2x4 corners that you built, then your whole barn is square.