Tabby walls were originally constructed in coastal regions with a concretelike slurry of equal parts lime, shells, sand and water. The mixture is poured into a timber framework and left to harden, and then the planks are removed and place above the prior pour and the method starts again. The wall slowly grows taller using several layers of building and healing time.
Mary-Bryan Peyer Designs, Inc..
The stacking process used to pour the tabby walls in layers could be viewed in the flat lines of the wall.
Christopher A Rose AIA, ASID
The shells of a tabby slurry are clearly observable in the risers and wall of the contemporary stairs.