Failing retaining walls is a common concern we see in landscapes. While it's tempting to try and save some money on a project, we strongly suggest this is one you don't DIY or hire unqualified landscapers*. Installing retaining walls takes professional expertise and a skilled hand to get a long-lasting wall.
The most common issue causing wall failure is improper drainage, which is especially prevalent in the NW with our substantial rainfall. Without proper drainage, the soil behind the wall becomes saturated and excessive force is placed on it. Hence, professionally installed drainage is essential in building a wall that will withstand our rainy climate.
For any structure to be stable, it's all about a strong foundation. For example, proper preparation, including compacting the soil and gravel, is essential. Also, conducting adequate site investigation, and proper footing depths assist in building nice, strong foundations.
Choosing an unqualified landscaper or a low-ball estimate can lead to a disastrous outcome. Sadly, unsuspecting homeowners may not know it's poor quality until a year or two down the road, taking a few rainy seasons to deteriorate. If your landscaper isn't properly licensed to do this work, they won't know to perform the unseen work underground, which is essential in building a strong wall. Also, low-ball estimates usually cost you in the long run. To cut costs, we've seen marginal drainage, inadequate base materials, and overall cheap materials used.
While working with your landscaper, it's essential to communicate future plans for your space, as unplanned uses can result in unexpected loads on your wall. For example, do you plan to install a shed, or park a car nearby? If so, the added pressure could result in a failing wall. Communicating your long-term goals with your designer is a crucial step to ensure the longevity of your wall.
*Make sure your landscaper is licensed, bonded, and insured. Also, look at years in business and visit the Oregon LCB website to verify a license.