1 © Stephen Tisdall 2021. Abstract- The design of reshores or backprops for multistorey construction is not a simple process. Normal practice adapts “simple” design methods to arrive at reshore/backprop layouts which are in general use. These “simple” methods serve the industry well and are used every day without incident. As the concrete construction industry accelerates both the speed of construction and the use of environmentally friendly and blended cements, the high early strength associated with normal concretes may be delayed. Both faster construction cycles and slower strength gain will impact reshore and backprop design and it is wise to be aware of well- proven formwork systems that reduce or eliminate the need for reshores or backprops. This paper is a “practical” look at reshoring/backprops and systems that reduce or eliminate their need. It is not a technical paper rather, it’s a practical review of some well proven alternative construction methods. Concrete construction/Formwork/Falsework/Shoring Reshores/Backpropping/ Formwork and shoring systems I. INTRODUCTION The construction of cast-in-place or in-situ suspended reinforced concrete slabs almost always require the introduction of additional propping. The additional propping is to facilitate the early removal of the formwork/falsework system for use on subsequent pours. This additional propping also distributes the loads form the slab being cast into the slabs below. In some cases, such as small area one-off slabs, the entire formwork system can be left in place until the concrete has achieved sufficient strength to be self-supporting. The more common case is the construction cycle requires the formwork or both formwork and falsework to be removed before the freshly poured slab has developed enough strength to carry the slab above. In some cases, the resultant loading from a freshly cast slab, formwork, falsework and construction operations will exceed the capacity of the slab below. This situation will then require this resultant load to be distributed into a number of previous cast slabs. Hence the requirement for reshoring or backpropping. This paper discusses a number of systems that reduce or eliminate the need for reshores or backpropping. EXPLANATION OF TERMS USED IN THIS PAPER. Falsework or Shoring will be used interchangeably to be that part of the temporary works that supports the permanent work until the permanent work is self- supporting. Backshores is a system of supports (For example: adjustable props) installed after small areas of the formwork and shoring have been removed. This process does not allow the freshly cast slab to take its own weight and deflect. Reshores or Backprops or backpropping, installed under the freshly cast slab after all or very large areas of formwork and shoring are removed. The freshly cast slab is allowed to deflect and take up its self-weight and any associated construction loads. Reshores must be installed with minimum load to be only “snugly” set, in order to prevent the introduction of additional/damaging loads into the freshly cast slab. A. Typical Approach to Forming Suspended Slabs in Multistorey Reinforced Concrete Buildings. All suspended cast-in-place (CIP)/in-situ concrete slabs require a suitable forming system to support the fresh concrete until the concrete floor is self-supporting. In most cases the self-weight of the slab being cast will Stephen Tisdall, AMICT, CGLI Certified Concrete Technician. Slab Forming Systems that Reduce or Eliminate the Need for Reshores or Backprops in Multistorey Construction.