Will a improper dam pitch leak? Yes

Frameless shower enclosures do not have frame to hold the water in. A polycarbonate sweep is placed at the bottom of the door to help with the sealing of the enclosure. Unfortunately water can get by and that is where the proper dam pitch comes in. The dam pitch is the most important part of the whole shower. Water runs down hill and if the pitch of the dam is to the outside of the stall, then the water will run out. We find that even when a threshold is placed on a dam that is incorrect, the water eats at the silicone eventually eating through causing mildew to grow and a leak. If your dam is slanted to the outside, your shower is going to leak. The only way to keep the shower from leaking is to have the dam repaired. 

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