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Reuben Saltzman

Don’t Caulk Here – Bath Tubs

This is another blog post by Charles Buell, a Seattle, WA, Home Inspector.

Let’s play “Myth Busters.”

Everyone knows that it is important to keep the connections between tubs and its shower surround well caulked.

I often find these areas recently caulked in an attempt to “spiff things up” for the sale.

Take a look at this first picture.  This is brand new construction—-doesn’t it look “SAWEEEEET?”  Don’t you wish you could lay a bead of caulk like that?

Very neat caulking at tub and wall connection

Before you get too envious (you knew this was coming) I am here to tell you that the caulk should not be there.

As commonplace as it may be—-as seemingly logical as it may be—-it is still wrong in many cases.  Caulking this connection is fine if the wall is some sort of one piece sheet or enclosure, but with tile it should not be there.  The grout joints are designed to prevent water from penetrating the wall but any small amount that does penetrate is able to evaporate out and/or weep out along the bottom.  If the tub/tile connection is caulked the water cannot wick out through the bottom grout joint and moisture builds up and is able to feed the mold that eventually develops.  I am sure you have all seen that grey discolored staining of the caulk that you would swear is “behind” the caulk—-where it cannot be cleaned off?  And you would be right—it is behind the caulk.

Mold behind the caulk at the tub and shower wall connection

The next thing that happens is that if there is enough water building up behind this area the water runs around the edge of the tub and down the walls behind the tiles “outside” the tub with the common resultant damage to walls and floors outside of the tub.  Sometimes this damage is just from water not being corralled into the tub by the shower curtain, but when the same thing happens with a shower door in place, these other factors may be at play.

These conditions also “complicate” the inspector’s moisture meter readings.

So if you have a tile tub enclosure—-keep the grout well repaired—-but don’t caulk the connection and the enclosure will behave itself much better.

Charles Buell

No responses to “Don’t Caulk Here – Bath Tubs”

  1. Peter Kusterer
    June 23, 2010, 3:36 am

    Reminds me a little of installing vent stack roof flashing. I have seen all four sides sealed underneath. By leaving the bottom edge open, you allow water to weep out the bottom.

    Although Oatey’s installation instructions call for “Silicone sealant can also be applied to the underside of the base to increase sealing power to the roof and is recommended in areas where frequent or heavy precipitation is common.”, they also state “The bottom edge of the flashing should overlap the shingles beneath it so it shed, not traps, water.”, i.e., don’t put sealant on the underside at the bottom edge which could otherwise trap water – no center nail, too, just the corners.

    Also, I recently saw an inspection report that caught the improper installation (by the roofer) of the vent stack roof flashing over the main electrical (service) pipe. The flashing was mounted over the shingles on all four sides, instead of “the top of the flashing will be covered one-quarter to one-half of the way down with roofing shingles.”

  2. Reuben Saltzman
    June 23, 2010, 4:49 am

    Great point, Peter. I’ve been thinking of more and more places where caulking shouldn’t be applied, and you just gave me one more to list.

  3. Katrina
    January 30, 2013, 6:23 pm

    I have a tile tub surround, and old caulk that’s gone bad which I’ve been planning to have replaced. The joint/gap is pretty wide though (probably a faulty installation on the tiles, which were there when I bought the house). Should I really leave a great big (at least 1/4 inch) gap above the tub without any sealant?

  4. Reuben Saltzman
    January 30, 2013, 8:51 pm

    The best thing to do would be to grout it, but caulking it would probably be better than just leaving a huge gap.

  5. katrina
    January 30, 2013, 8:53 pm

    Thanks. Given that there is some flex in that joint – meaning depending on the weight of whether tub is empty or not – should grout be applied with the tub full of water?

  6. Reuben Saltzman
    January 31, 2013, 4:40 am

    I have no preference. The one concern about filling the tub first is that it may compress against the grout when it empties.

  7. Mark
    October 19, 2013, 12:23 pm

    Thank you for confirming this! It makes sense to me that a surround of porous material would need to vent/weep. I’ve had the exact condition you describe about and could not confirm my suspicion that the bottom of the stone should NOT be caulked.

    I will be bookmarking and sharing this site.

  8. Eric Goodwill
    January 5, 2014, 5:13 pm

    This makes sense; however, can you please tell me the third party standard or specification that details this? Is it an association, manufacturer standard or both? I have never heard of it before. Thanks.

    Great Site by the way!

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