Building a Raised Planter Against a House Foundation: Waterproofing and Drainage Essentials

Building a block wall against a foundation is risky but possible with rigorous waterproofing: 1) fluid-applied thermoplastic membrane on exterior wall, 2) 10-mil poly liner, 3) mortar (not glue) first course on acid-etched slab, 4) rebar anchors epoxied into slab every few blocks, 5) interior waterproofing + weep holes (1" every 4 ft), 6) French drain (4" perforated pipe in gravel) at wall base with outlet through weep holes. Expensive and difficult—consider a freestanding bed instead.