Caulking a Tub

This plumbing trick is an oldie but goodie that works well when you need to caulk around a tub. Here’s how to go about it:

  • Scrape out the old caulk or grout around the tub.
  • Fill the tub with water to weigh it down.
  • Apply masking tape to both to the wall and the top of the tub, leaving a gap for the caulking.
  • Fill the gap around the tub with silicone caulking, and smooth it out.
  • Allow the caulking to dry overnight before draining out the water.

Further Information


  1. Why would u fill the tub with water in order to caulk it I never heard that before my brother has done construction all his life and he never put water in tub and every other video don’t do that and said it’s not good so why would u tell people to

    • Hi, Arlene,
      Filling the tub with water weighs down the tub and ensures it will reach its lowest point.
      Caulk compresses well, but handling tension is a different situation, so filling the tub with more water than it will ever need ensures the caulk has reached its ‘maximum’ tension.
      This is an old plumber’s trick.
      Thanks for your question. 🙂


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