With more and more of our cites rebuilding and expanding, some rather specialized construction problems have arisen. One situation frequently encountered by contractors is placing concrete against an existing material or surface. The problem is to secure and hold formwork in place. The answer to successful one-sided forming and placing lies in the use of ties and the way in which they are secured into the existing surface. Some surfaces, such as rock, are very stable, while others can cause problems. Old concrete which as been exposed to the elements over many years may have deteriorated, making the tying a real problem. There are many types of forms and ties that can be used for one-sided forming. One type of tie is threaded so that it may be welded at one end to the steel piling and bolted in place to the formwork. The threaded area provides for proper adjustment and form alignment. Another type of tie employs the toggle principle of anchorage. For steel it may be welded, or if used with wood, a hole is drilled and the toggle inserted so that the toggle bears against the outer surface. There are methods, materials, and equipment available today that will help make one sided forming more of a routine matter. However, the things to watch and plan for remain the same: (1) check the surface to be placed against, selecting the proper anchorage material. (2) Select the forming material or system that will provide the best versatility. (3) Use ties of adequate strength and follow the manufacturer's recommendations. (4) Provide for waling, strong backs, and bracing as required. (5) Watch the rate of placement, avoiding overloading of the ties and forms. Remember the existing side will probably not heave the stability and strength of the formed side.