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These will be used to set the walls of your foundation. Each of these boards will need to be about 2 feet by 10 feet (an inch or two thick). The shorter sides of the boards will sit down, on top of the initial concrete layer. You will need enough boards for both the inside and outside of your trench footing, so that there is no space in between the boards. You can add in a little dirt on the outer part of the outside boards to help them stand firm and upright. Use metal bars outside of the wooden frames in order to hold the boards tightly together. You can also cut boards or plywood strips 6 to 8 inches wide and 2 to 3 feet long and use duplex nails to span across the joints of your foundation boards to hold them together. Be sure all of your staking is sturdy or you risk "blowing out" the boards and losing all of the concrete. Use plenty of stakes to prevent this from happening. Once more, make sure that you have the correct mixture of concrete. How to Make Concrete In general, you should form the entire job and pour all the concrete at once with a concrete truck. How much wall is exposed over top of the ground depends on the level at which your building will rest. Drill 3-4 holes about 6 inches apart. Do this to each side. Insert a pin into each of these holes. This is important because if you do not insert the pins, your walls can shift, causing the building to collapse. Pour the second and third walls coming off of the initial wall. The concrete will form over the pin and join the walls together. Reinsert pins into the sides of the second and third walls. You can use a hand float and go over the tops, making sure there are no cracks and crevices. You should also use an edger to go around the edges and smooth them over. Let your concrete dry, and then remove the frames. You will want to do this soon after the concrete dries, otherwise the wooden frames can get stuck. Try to pull them up from the top, so as to not damage the newly poured foundation walls. These sprays can be found at most hardware stores at very low prices. It is basically a can of spray cement. Adding this extra layer of protection will prevent water and other liquids from damaging your foundation. Make sure to spray on both sides of the wall.
Set up your wooden frames. Mix concrete and pour your foundation walls. If you are pouring next to an old foundations this should be pinned to the new foundation wall. Smooth over the tops of the concrete walls. Remove the wooden frames. Spray your foundation walls with a waterproof coat.