The foundation on which a retaining wall would sit on is critically important if you are planning to construct one. There are several aspects of the foundation for retaining walls which one must be aware of to prevent the wall from collapsing or even sinking. A lot depends on the quality of soil on which the foundation is being built. For instance, some areas easily permit a retaining wall to be built directly on the ground whereas in areas where the soil has been dug up or disturbed during the past few years, a concrete footing should be installed before building retaining walls. This is also necessary if the soil is a type which compacts easily. This prior step is necessary for preventing wall from sinking.
Whatever the soil type, to create the right foundation, you must ensure proper drainage on the inside base of the wall. It is worthwhile to remember that wet soil is twice as heavy as dry soil. So when the soil is saturated with water, it sinks lower with time as the water tries to escape deeper. This naturally applies a lot of pressure on the reverse of the retaining wall which may gradually start getting inclined or move forward – especially near the top portion. One of the best ways to ensure right drainage is to install a perforated drain pipe which is situated perpendicular to the wall and installed at the inside base. The perforation of the drainage pipe allows all the excess water to seep through and move away from the retaining wall. The essence of this exercise though is to find an escape route for the excess water from the soil. You could either connect the perforated pipe to the home drainage system or by providing a right-angled exit point through the retaining wall situated at the lowest point. Before placing the drainage pipe it is wise to place a one or two-inch layer of crushed stone all round it. This prevents the drainage pipe from getting clogged with residual soil.
Retaining walls can be made from treated lumber, rocks or even cast concrete blocks which interlock at an angle as they are stacked one on top of the other. Whichever material you use for building a retaining wall, make sure the foundation is tough and sturdy – providing adequate drainage is one of the ways which strengthens the foundation. A retaining wall is the answer when you are trying to level a steep slope in your property or enclose a specific area to grow a garden. Building a concrete block retaining wall is perhaps easier than one may think. With each block having a lip which locks to the previous row, the blocks are easy to assemble and install a wall up to 30” tall. Of course for walls which are taller, you will have to work on the foundation more, with additional efforts for stabilizing and reinforcing the soil for making it sturdier. If you are wondering the quantity of concrete blocks that you will need for constructing the retaining wall, remember, each block is one foot long. So now you could calculate the approximate number of blocks which are needed for a wall of your size. It is also important to remember that curves require more number of blocks than a straight area. To build a retaining wall successfully it is important for creating a foundation with a run of blocks. These should be placed below ground level so that the soil can hold it firmly in place.