This is going to be one of my most interesting projects.
It's helpful that my approach is always to build the base first - that way I can be sure of measurements before I start. In this case I found that the concrete slab was very uneven and sloped away by around 6 inches to the front. I built the walls up to a level point by the 3rd course and now it's done I can get on with constructing the rest of the greenhouse.
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