What is a Drip Inducer or Water Cut
A drip inducer also known as water cut can be a recess, protrusion, groove or a projection on an underside surface. The function of drip inducer is to interrupt and break the flow of water along the surface thereby causing it to drip off. One of the most common day today application of water cut can be found at the edges of kitchen slab. These grooves or notches prevent water from seeping into the shelves.
In absence of water cut, the water running down from the sides of structures are spread over the soffits which cause staining. Prolonged exposure and dampness will reduce the durability of the structural component. Water gets accumulated at the drip inducer, by breaking the path of water flow and drip off from the structure due to accumulated weight.
A tapered recess or notch serves as a water stop. The walls of the notch will be either sloped or curved as shown in the figure. In other cases, the edges itself are projected downwards as a downstand to serve as a dip inducer. While specifying water cuts, it should be noted that the walls of recess shall be sloped for easy removal of formwork. However, right angled cuts are highly efficient in water shedding.
Further it should be taken care that the introduction of recess doesn’t affect the desired cover provided to the reinforcement. Maximum effective size of drip inducer shall be 75mm wide to 25mm deep, 75x25mm. For bridge decks, drip inducers are provided to prevent water seeping towards underside of deck which can cause corrosion of steel girders.
The water cut is continuous and it is provided in all vulnerable areas and that are prone to water flow. While selecting the location, it should be such that the dripped of water should not accumulate in another critical area like bottom flanges of the girder.
Water cuts and drip inducers are also provided by attaching continuous plastic or an aluminium strip using rivets along the edge of concrete. These strips are typically 20 to 25mm thick. Though these are not aesthetically pleasing, they are effective. The depth of drip inducers provided using projection or downstand shall not be less than 50mm for effective water shedding.