Can I use grout between the tile wall and tub? I see references to caulk
being used and I have tried that. It never seems to last very long and
tends to pull away from the tub/wall surfaces.
Any ideas? Chuck B.
Grout is typically used between surfaces that have no relative movement.
I.E. between two adjacent tiles.
You use caulk between surfaces where relative movement is likely. For
instance between two items with different coefficients of thermal expansion,
or between items that expand differently with humidity. Grout would fail
quickly in those applications.
The correct product for your situation is caulk, but it is important to pick
the *right* caulk. Don't cut corners by using painter's caulk or another
product that really isn't designed to get wet every day.
Sure, you an use whatever you'd like. It just won't hold up well.
Tubs flex when you add hundreds of pound of weight in water and people.
Flexible caulk like the silicone based is best as it will flex with the tub
movement. Grout will crack in days.
Additionally, before you caulk around the tub, fill it with water first.
That way, the space between the tub and the bottom of the tiles will be
its greatest as the weight of the water will separate the opening.
Caulk at this time and empty the tub after the caulk has had a chnace to
cure. With the tub empty, the bead of caulk will be under pressure, but
will not come separated when the tub is filled.
"Never ascribe to malice what can equally be explained by incompetence."
There's a certain amount of flex that's required at the tub/tile
junction. Grout does not like to flex and will crack. Caulk will last
longer - a lot longer if it is done correctly. Almost nobody does it
The usual way people caulk such a seam is to fill it with caulking.
This will not last. Caulk will not stretch in all directions at once.
The thickest part of the caulking is obviously the least likely to
stretch. Therefore you have to direct the caulk's movement.
Backer rod - essentially a length of foam rope - is inserted into the
joint to limit the depth of the caulking. The caulk will be thicker at
the upper and lower ends, maximizing the amount of caulk at the contact
points of the different surfaces, and thinner in the middle. Basically
an hourglass shape. The middle is now the thinnest section and the
elongation will take place there. The thicker sections at the contact
points also increases the amount of caulk and adhesion at the critical
That is the correct way to do it, and as I said, almost no one does it
that way. There are other ways to do it using bond breaker tapes - do
a Google if you're interested.
I wouldn't use grout which is hard and not flexible. I always caulk.
Like GE Silicone II. This is no brainer. If it puuls away, you did not
prep. well before applying caulk. No dirt on the joint, and it hast to
The responses that advise against grout are mostly right,
If the tile was set into a mortar and mesh base, and you have a
cast iron tub (both of which were standard construction in the 50s
and earlier), and the tub is on heavy joists near an exterior wall
or internal supporting beam, there will be no movement and grout
will work. It has held up in my house for 20+ years.
You can also use the grout as a substitute for the backer rod
mentioned in another post. Just keep it about 1/8" deeper than a
normal grout joint so that you can apply enough caulk. Eventually
the caulk will mildew beyond saving and you'll have to cut it out
and replace it. If the caulk is just a thin coat over grout, it
will be a royal pain to remove.
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