Retaining Wall Foundation Design

a retaining wall with tools leaned against it
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The foundation design of a retaining wall varies according to the type of retaining wall you choose to build in your garden. Retaining walls are structures that help to retain soil pressure in a lateral direction. Here are a few tips to design the foundations of the different kinds of retaining walls. A proper foundation base must be made so that the wall resists the pressure properly, without crumbling down.

Tip 1: Materials

Remember a wall is only as strong as its foundation. The material used in building the foundation is of immense importance. Crushed stone or gravel is a good option. You may use earth that has been compacted. After digging up to 1 foot deep into the soil, ensure that the foundation stones are placed in a manner that the largest form the bottom-most layer and that the width of the foundation base is laid such that the stones or gravel is set evenly without any ups and downs. This makes the foundation well equipped to support the walls.

Tip 2: Strengthening the Base

Along with the foundation material, flagstone rock, paving log poles, molded concrete units can be added to strengthen the structure of the wall. Make sure that you check where any drain pipes are below the soil, and that the foundation does not interfere with them.

Tip 3: Cantilevering

Generally, cantilevered walls have a strong foundation design. In this case, the wall is better equipped to handle the retained material, due to the effect of gravity. The foundation in cantilevered walls requires the building of a concreted foundation, into which a steel stem is installed before the concrete sets up. Due to this technique, the pressure is conveyed down to the footing underneath the soil. The horizontal upper pressure is altered into vertical pressure. For this design to work, you need to dig below the level of frost depth.

Tip 3: Gravity Type Foundation

For simple drywall, built by stacking slabs or rocks like limestone, you need not dig too deep below the soil. Simply line up the foundation base with crushed debris and roughly mortar it up. On this base, you can arrange the slabs or the materials for making the gravity retaining wall. The foundation base may be made of concrete rods, which help to reinforce the soil in its position.

Tip 4: Sheet Pile Foundation

If the soil in your garden is of loose and soft quality, you may want to build a sheet pile style foundation. For this, you need to insert steel or wood planks 2/3 deep into the soil, with the top 1/3 remaining above the ground. This foundation design ensures good resistance of pressure in areas prone to frequent rains.

Tip 5: Wood Wall Foundation

Another retaining wall material that is immensely popular is wood. For such walls, make sure that the area where such a wall is to be erected is leveled. Make holes, so that the support beams to be inserted vertically fit in. The dimensions will vary according to the height of the wall itself. Ensure that at least 40 percent of the support beam is underground and that there is a space of at least 1 foot between the beams installed. The concrete and gravel must be mixed in equal proportion, to fill in the gaps in the foundation holes. Such a foundation design is very strong and helps the wood wall withstand immense pressures.