The British Lift Slab (BLS) was a method of construction devised by the company of the same name. The construction method basically involves the erection of reinforced concrete columns around which a continuous reinforced concrete floor slab is formed. Once set and in place the floor slab is then mechanically jacked up around the column and wedges inserted to secure the slab to the column. A concrete cap is then cast to protect the joint between the column and the underside of floor slab.