Hardscapes - Retaining Wall Design
Retaining Wall Design
Introduction
Retaining walls are load-bearing structures that stabilize a slope and protect planted areas from erosion, but they can be used to do much more depending on the design chosen to build them. Retaining wall can add depth and texture to completely change the shape and feel of an environment and it can even create spaces. Deciding on appropriate wall design is driven by several factors like cost, skilled labor, materials availability, building codes, site accessibility, aesthetics, local building practice, etc. But the most important factors to consider are those that would ensure a long-term satisfying retaining wall performance. Design Considerations
When designing a retaining wall, there are generally five important elements to consider:
Materials: There are a lot of architectural materials to choose from but it is important that the chosen materials are the ones best suited for the desired result.
Type of wall: Each landscape site has different needs, soil conditions and slopes and these things must be evaluated and considered in choosing the type of wall.
Location: Exact location should be decided on so as to avoid unnecessary expense in relocating and modifying already installed retaining wall. Proximity of the retaining wall to structures behind it must also be considered. There must be adequate clearance to allow space for attachment or future enhancements on the wall. Drainage: All walls should have a gravel backfill, or drain pipes to allow water to drain freely from behind and away from the wall. Most retaining walls fail because of pressure against the wall caused by water or soil-moisture build up behind the wall.
Foundations: A wall is useless if it does not have a good foundation, and all retaining walls should be built on properly designed foundation with sound and compacted sub-base material. Stability of the retaining wall must be evaluated for both short-term and long-term condition.
Retaining Wall Materials and Designs
Concrete
Concrete is a core building material for retaining walls. Choosing this design thus means that the wall is going to be stable and would need very little or no maintenance. This design is good for retaining landscaping, stairwells, or grade changes.
Interlocking
Interlocking retaining wall design is good for adding aesthetics to a landscape, however, this design is very susceptible to built up water weight in soft soils. But dimpled membrane with drain tiles can remedy this problem. They help remove the extra water weight from the wall and drain it down to the drainage system. Wood
Wood retaining walls are made from a pressure treated wood and are easy to use. Wood gives a warm organic look to the landscape design at a relatively low cost. However, wood is subject to moisture, rot, and termite. It is important therefore to have a waterproofing protection on the backfilled side to extend life of the wood retaining wall. Insulated Concrete Form
Insulated concrete forms (ICF's) are made of concrete poured between two layers of foam panels and is a good design where there is a heavy or unstable soil and steep slopes. But water drainage and waterproofing must be added to the design to prevent water seepage. 
