Considered a quick-fix option for most situations, waterproofing tape strips can be used in any situation where you have an inside corner transition that needs to be protected against water. While it can be used for tile showers to seal corners, caulking is always preferred for several reasons.
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Properties of Tape
Waterproof tape strips are intended for areas requiring a quick and easy way to provide basic waterproofing treatment for inside corners. Rather than filling a void as caulk does, tapes are adhered to the surface of the two materials that meet up in an inside corner, covering rather than filling the void between them. An adhesive layer along the back of the tape helps it stick to the surface area.
One of the downsides of tape is that its adhesion fades far more rapidly than caulk. This is because tape is an exterior application method, which means the water is transitioning down the wall to a material that extends further out than the surface of the wall. Natural gravity and water wear away at that joint, eventually working their way through. At this point the tape begins to fall off the wall.
Caulk is superior for shower installations because it fills the void rather than simply covering it. Empty sections behind the edges of the two materials also get filled. Water has no surface to weaken on its way down to the drain. Caulk also cushions the endpoints of the two installation materials, helping provide elasticity for the surfaces.
Tape will last for 10 years or more in ideal conditions, whereas the most basic caulk usually lasts about 20 years. The higher the quality of caulk, the longer it will last, with some polyurethanes rated for 35 years or beyond. The lower the quality of tape, the less time it will last. Further, if you live in a particularly humid area, the tape can become saturated with moisture and eventually peel off.