If you're a leak seal contractor, you may be familiar with this situation: A property owner with leaking concrete calls you up and says, "Hey, everything is dry right now, so I want to get someone out here to go ahead and waterproof the structure."  Attempting a waterproofing job when the structure is completely dry is not recommended.

Let me give you an analogy. Let's say I hired you to paint a basement. And when you arrive, it's pitch black in that basement. No lights are available and you can't see anything. Can you still paint that basement? The answer is "yes", but when we turn the lights on, will I be happy with the job you've done? There's no way. It would be a terrible paint job.

Similarly, if someone is asking you to waterproof while it's dry, you are basically attempting to seal leaks while blind. You need to waterproof while water is present - not just to activate the grout, but to see where the grout needs to be. Let the leaks lead you to correct grout placement. You won't know for sure if the water is not present. If you attempt a leak seal job in a completely dry environment and then return when the water is present, you'll most likely find leaking cracks that you missed.

Moral of the story? Grout when it's wet.

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