Waterstops play an important role in keeping a fountain from leaking in a number of different ways. They are used for piping penetrations as well as at structural cold joints and at expansion joints that are expressed through fountain basins. They have been in use for many years for structures and previously were made of copper or lead.
Waterstops for pipes are also known as puddle flanges and paddle flanges. These devices are manufactured from a number of different materials including brass, stainless steel, pvc and even rubber. The need for these devices comes from the conditions created by curing concrete. As concrete cures, it shrinks and can pull away from smooth pipes, especially pvc which does not provide a good bonding surface, and provide a path for leakage. By placing a plate or flange in the concrete perpendicular to the pipe, the concrete’s own weight has a larger surface area to bear on, creating a positive seal.
In the past, you had to fabricate waterstops for the type of piping material you were using, but now many types are commercially available. When passing through a pool structure, we usually specify bronze waterstops as we typically change from PVC to brass for any pipe exposed in the pool. If you are terminating at an embedded fitting such as an eyeball or drain, we look for fittings that have the waterstop built into them.
In some cases the structural profile is such that you cannot physically fit a waterstop in, or for labor and cost savings you want an alternative to the mechanical types of waterstops, you can use waterstop materials that are installed with a caulking gun. This type of waterstop is also good for uneven surfaces on renovation projects.
A third type of waterstop is primarily used on concrete cold joints, where one concrete pour stops and another begins. This type is called a hydrophilic waterstop and comes in different sizes and profiles, but is normally installed with an adhesive on the existing concrete. When the concrete is poured the waterstop is embedded in the joint and will swell and seal if water leaks into the joint. Care must be taken to properly embed the waterstop to the manufacturer’s instructions to avoid spalling of the concrete edges.
Waterstops also come in PVC material with different profiles, often called dumbells. These types of waterstops are good to use for movement joints and expansion joints as many of the profiles have a center bulb that can expand and contract with the movement of the structure.
Whichever type of waterstop you use, make sure you read, understand and detail and specify all manufacturers recommendations applicable to your installation.