There are many kinds of home foundations, each with its own pros and cons. Concrete, whether in cinder block form or poured form, is by far the most popular. Other foundations include wood, brick and stone. Concrete is the strongest and most durable material, and the result is that it is the most common. Cinder blocks have the added advantage of being likely the least expensive of all the options available.
The cinder block can be made out of many materials. Most commonly, it is a concrete block that is hollowed out by two cells. These two cells are then later filled with concrete and, vertically, rammed through with iron or steel bars for added support. The blocks are cemented together with mortar. This method is cheap and easy, and is probably the most common do-it-yourself foundation type. Poured concrete takes specialized labor.
The cinder or concrete block is 8-by-16 inches, which includes the mortar. That means that when you buy the block, it is smaller than its normal dimensions by 1/8 inch, since room must be left for the mortar. If you are putting a block foundation together yourself, the best bet is to build the wall dry first to see how it will look and feel fully complete. Then, use the masonry concrete to build the wall permanently. It is a good rule when laying block to spread the mortar wide enough for about three or four blocks at the most. If you spread it too far, it might dry too much before receiving the weight of the block.
The cinder block cannot stand on its own. Three additional items are necessary. First, the “footer,” or the lowest part of the foundation, is made of concrete. The rule of thumb is that the footer be buried twice as deep as the wall is thick. The second is that the footer be twice as wide as a single block. Finally, the block wall is often attached to a poured basement floor that gives it extra stability. The basement floor, in other words, is one piece of poured concrete that is then attached to the block wall.
All foundation types have their problems. For cinder block, the major areas are leakage and cracking through the mortared edges. These are the weak points of the structure. Cinder block, like all foundation types, changes after many years of freeze-thaw cycles. These cycles are the enemy of all home structures of whatever type. Some bucking or leaning might occur over years of this. If your floor is attached to the wall, the top of the block wall might lean, while the bottom parts remain attached. Blocks will slowly give under intense hydrostatic pressure or the weight of the soil pressing on the wall. Both thickness and depth can guard against this, yet, no foundation type can exist leak or crack free forever.
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