Concrete is the perfect medium for water retaining and water excluding structures such as Dams, viaducts, swimming pools, basements etc. However, concrete structures are only as watertight as the construction or expansion joints in the structure. As the name suggests, a waterstop stops water and is typically installed in concrete joints to prevent water ingress. Waterstops can be broken two broad categories – swellable waterstops and static water stops. Swellable waterstops are placed centrally in the joint and expand in contact with water to create a seal. Static waterstops are generally a PVC profile which is cast 50% into the first pour and the remaining 50% is cast into the second joint creating an impermeable barrier between the two sections of concrete.