A pony wall is a short wall. In different circumstances, it may refer to: a half wall that only extends partway from floor to ceiling, without supporting anything. a stem wall, a concrete wall that extends from the foundation slab to the cripple wall or floor joists. a cripple wall, a framed wall that extends from the stem wall or foundation slab to the floor joists. a knee wall, which extends from the floor to a countertop, rafter, or handrail. Types of wall Building engineering