- 1). Determine where the concrete fence will be located. For rough estimates, mark the length or perimeter of the fence. Choose the height of your fence within the limits of local government codes. The codes are for your safety and for ensuring that your structure will not intrude into other people's property. Draw a rough design on paper.
- 2). Select the concrete block size you will use. If you plan on using more than one block size in your concrete fence design, note the dimensions. In reality, the dimensions of the blocks are not exact. For example, a 12 inch by 8 inch by 16 inch block is really an 11 and 5/8 inch by 7 and 5/8 inch by 15 and 5/8 inch block. If you join the blocks and put 3/8 of an inch of mortar in between, your block becomes a 12 inch by 8 inch by 16 inch block.
- 3). Calculate the amount of blocks you will need for the length of your concrete fence. If the length of your fence is 20 feet and 16 inch long blocks are used, convert feet to inches or inches to feet. For this rough estimate, 20 feet is 240 inches. Divide 240 inches by 16 inches and the result is 15 blocks. Fifteen blocks are needed for one row. In your drawing, assume that the spaces of the joints are three-eights of an inch.
- 4). Minimize concrete block cutting, if possible. Design the fence to have a length that will be rounded to the nearest block or half block. For example, if your planned fence is 21 feet, 15 and ¾ of a block would be required for one row. The length could be reduced to 20 to get 15 blocks or increased to 22 to get 16 and ½ blocks.
- 5). Estimate the total number of blocks to be used for the project. Twelve-inch blocks will be used as an example. If 15 blocks are used for one row, and the height of the fence is 6 feet, then 15 by 6 equals 90 blocks. You will need to account for mistakes and add 10 percent of extra material, resulting in a final total of 99 blocks.
- 6). Determine the amount of rebar needed for fences over three feet. Rebar will provide more strength to concrete and helps to make it last longer. Placing vertical rebars every two feet will reinforce the wall to resist horizontal cracks. Installing horizontal rebars along the length of the wall will prevent vertical cracks. In this example 20 feet of horizontal rebar is needed for the top of every row. This amounts to 20 feet by 6 rows or 120 feet. For the vertical rebars, 20 feet is divided by 2 and the result is 10 pieces. However, you actually only need nine pieces, since the rebars are in between. Nine times 6 feet is 54. A total of 180 feet of rebar -- plus extra -- will be needed.
- 7). Plan for stepped foundations, if the ground along the length of the fence is sloping. The concrete fence also will be stepped as well. The result will be a concrete fence built in large square- or rectangular-shaped sections on different steps. If the slope is not steep, the entire path of the fence's foundation can be leveled the entire way.
- 8). Account for the amount of cap blocks that go on top of the concrete fence. You do not want to exceed the approved height limit of the fence too much. For example, if you put 4-inch caps on a fence that is six tall, this will add another four inches. To get the desired height plan, choose blocks of 8 inch by 8 inch by 16 inch pieces before the top row, and 4 inch by 4 inch by 16 inch block caps for the top row.
- 9). Design a complex concrete fence with decorative blocks. Not every block has to be a plain one. Be wary of decorative blocks that are not of standard size. They may be smaller or larger than the standard cement blocks. Be creative and find ways to integrate the pattern of unique blocks with the standard blocks. For example, you may want to build the first four feet as solid cement blocks and then build the next 2 feet as decorative blocks. Another option is to have a section of the wall that is entirely plain and have other sections built with decorative blocks.
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