harry wrote:
On May 10, 6:44?pm, "Jay-T" wrote:
I am having new ceramic tile installed on my shower/tub surround.
?The job is being done well -- with cement backer board etc.

My question is about the 1/8-inch gap between the bottom of the
ceramic tile and the existing cast iron tub. ?Should that space be
filled with grout and then use 100% silicone caulk, or should there
be no grout there and only use 100% silicone caulk?

As there could be movement between the tub & the wall you need
silicone caulk or better still there exists soft plastic "angle piece"
with a fin that goes under the bottom tile and rests on the tub. A
permanent stain resistant solution that never leaks, cracks, comes
unstuck or goes hard.
(At least it exists in the UK. Most of the stuff I see on the net is
about caulk in America. Maybe you don't have it)

Thanks. Maybe the "angle piece" is a UK thing. I found this YouTube video
that I think shows what you are referring to at about the 1:24 minute point
in the video:

http://www.youtube.com/watch?v=9J-mPhNlyBo