Dear Robin:
Dear Worried :
Congratulations on the purchase of your dream home. It is frustrating to be worried about your backyard but you have reason to be concerned. Adding more gravel is likely not going to stop the erosion that is occuring. If enough of the soil and gravel erodes from behind the boulders, it can cause a collapse. A retaining wall over 48 inches (from foundation), whether built with boulders or concrete wall blocks, is required by most municipalities to be designed by an Engineer. There are specific codes and design specifications that address water flow, grade and drainage, and erosion. The type of soil beneath and surrounding the retaining wall can be a vital influence in the design. If a wall is showing signs of disintegration or distribution of building materials , then it is important to have the retaining wall evaluated for structural integrity and longevity of life left in the structure. There are many things that could be occurring to cause the deterioration. An experienced engineer in evaluating retaining walls can make appropriate recommendations.
