I have a sloping yard and want to create mini terraces with decorative retaining walls along the hillside. None of the walls would be more than a few feet wide or 2-3 feet tall. Do I need to include a drainage solution? Is it OK to DIY this with lots of research? If not, what should I expect to pay a professional?
Drainage is key. Back it with 6-12 inches of rock if you want to be meticulous. Wall sounds small enough that it might make no difference.