Newbie question: Grout or Caulk in shower stall

Discussion in 'Shower & Bathtub Forum & Blog' started by Van Hammersley, Jun 1, 2011.

  1. Van Hammersley

    Van Hammersley New Member

    Jun 1, 2011

    I'm not a very big DIY type of person, especially with this type of fix. I'm also new to the forum. Hopefully someone might be able to shed some light on my issue below...

    My wife and I just bought a house that has a shower stall in need of help. The joints between walls and walls/floor have some small/very thin areas of separation (cracks) where it looks like water/moisture could get through. These areas a smaller than 1/8th of an inch wide.

    I'd like to try and fix it myself, but have a few quick questions:

    1. Should I use grout or caulk? (I have a friend who wants to help, but is saying I really need to grout?)
    2. If caulk is in order, is there a specific type I should look for (grout in bathroom is white, so assuming any white caulk would be ok?)
    3. Aside from cleaning the joints/cracks, would i need to clear out/cut out any of the grout there or ok to caulk/grout over after cleaning?

    Below are some photos I took of the shower stall. Any help would be greatly appreciated! Thanks!

    IMAG0104-1.jpg IMAG0106-1.jpg IMAG0102-1.jpg IMAG0103-1.jpg IMAG0105-1.jpg
  2. jimbo

    jimbo Plumber

    Aug 31, 2004
    San Diego, CA
    There is an excellent basic rule which will keep you out of trouble:
    Lines and seams in one plane...on the wall or on the floor = grout'
    lines and seams at a change of plane, i.e in a corner of the wall, or where the wall meets the floor = caulk. use matching, coordinating, or clear color.

    The reason is that there will be flex at that change of plane. Caulk is plenty flexible enough to handle that, but grout is not.
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  4. jadziedzic

    jadziedzic Member

    Aug 4, 2006
    New Hampshire
    Use a 100% silicone caulk - not a "siliconized latex" or "latex" or other variety. In order for the caulk to properly adhere any existing grout should be removed from the joints to be caulked, and the surfaces to be caulked should be cleaned well prior to caulking. Over on the John Bridge tile forum there's an excellent tutorial on silicone caulking for the beginner - I suggest you toddle over there and read it (

    Also note that grout (and many types of tile) are not 100% waterproof, so water *will* make its way through the grouted joints. In a properly-constructed shower this will not be a problem, as the materials under the tile should ultimately direct the water to the drain.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    If the depth of the joint is greater than the gap, you should use a foam backer rod stuffed in there before installing the caulk. It's farily cheap and comes in various diameters to match the gap (should be slightly larger so you compress it slightly to fill the gap).

    Many grout manufacturers sell color-matched caulks. If yours doesn't there are aftermarket companies that make it in both sanded and unsanded styles to match the grout. If you get the proper one, it is very hard to tell what is grouted and what has caulk. A deep gap with a foam backer rod will flex better and seal better which makes it last longer.

    You need to clean out the old joint first. A utility knife (get extra blades as they'll dull quickly) can often clean out cracked grout fairly fast.
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