Grout or Caulk between new tile and bath tub

[pkmicro]

I have just finished laying 20x20 Porcelain tiles on my bath room up-stair. Should I use grout or caulk between the Bath Tub and the new Porcelain tiles? TIA

[trader4]

Caulk. There will be some unavoidable movement between the two, due to temp differences, tub weight changing with water, etc. Caulk flexes, grout cracks.

[Robert Allison]

Caulk designed for wet locations. Fill the tub with water, then caulk.

[Wayne Whitney]

That depends. Caulk is flexible, which is good at the joint between two dissimilar materials that may move differently. Grout, in my experience, is good because it doesn't support mildew growth as much as caulk does.

So if your bathtub is acrylic or steel, it will move too much for grout, so use the caulk. If your bathtub is cast iron, which is pretty rigid like your tile, you can use grout, and it will be easier to clean. If it develops a few small cracks, you can seal those with a very tiny amount of caulk--don't cover the surface of the grout with caulk, or it will defeat the advantage of the grout.

Cheers, Wayne

[Roger Taylor]

Something flexible and mold resistant. I use GE Silicone bathtub caulk. Make sure the cartridge is fresh - shelf life is short, and the use-by date is on the base of the cartridge. Also, if you haven't practiced applying silicone grout to a seam, do some practice on a 90-degree inside corner of scrap. You actually need only a fairly thin bead, but it should be finished flat, using slant-cut nozzle, so it doesn't bulge out and look ropy. Roger

[Heathcliff]

That answer seems very logical, but having observed many bathrooms, it seems that the usual practice is to use grout and it works fine. I used grout along the steel tub when tiling my bathroom and it has never cracked or separated. And it avoids the problems with caulk: one, a good smooth caulk bead is hard to get for a DIYer, and two, it seems no matter what kind you get it supports mold eventually. -- H

[Bob F]

If you choose your grout carefully, you can get silicon caulk to match the grout color. On mine, the match is not exact, but it is close. The caulk is only available for some of the grout colors, for some manufacturers. Talk to a good tile shop for availablility in your area.

[TH]

Grout with a good latex sealer. Caulk will eventually get mold spots.