I got tiles, premix thinset, "blue board" water resistant sheet rock
in preparation to replace a section of tiles in my shower stall. The
guy in that dept where I got the stuff at Home Depot insisted I don't
need spacers for the tile, that shower stall wall tiles are supposed
to be butted up against each other.
All the "how to" videos I see on YouTube show the use of spacers for
setting shower stall wall tiles. You think this guy just didn't know
what he was talking about?
If he worked at Home Depot it's pretty much a given that they're
talking out of their ass. Sad, but true.
The wall tile do indeed have lugs on the sides that space the tile a
bit, but there are problems with having such a thin grout line. It
leaves no room for error and if you run off even a little bit laying
the tile it will only get worse as you continue. It also makes it a
pain in the ass to regrout should that ever be necessary. Too thin of
a grout line is as bad as too big of a grout line in wet areas. Go
with the spacers - 1/8" or a bit more is about right with 4x4 or 6x6
BTW, blue board is for plaster, green board is moisture resistant and
should _not_ be used in a shower.
They told me that this stuff - actually kind of a purple color -
replaced green board and is what you would use in a shower stall.
It's made by Gridmarx, says manuf'd to ASTM Standard C1396 and CSA
If not this, then what should be used in a shower stall?
I pulled this off one web site:
"Backsplashes, Shower Stalls & Tub Walls
Water resistant greenboard sheetrock should not be used for walls that
will be subjected to heavy amounts of moisture. This includes but is
not limited to, shower stalls and tub enclosures. Greenboard is water
resistant but not water proof and will disintegrate if it is exposed
to excessive amounts of moisture. It no longer is approved for use
(ANSI A108) as a wet substrate. Depending on moisture conditions, this
product is acceptable for use as a ceramic tile substrate in
residential backsplashes and bathroom wainscotings."
I'd never heard of the stuff, but, again, the HD guy seems to have
been talking out of his ass.
Here's the Gridmarx manufacturer's web page - has nothing at all on
any water resistance properties.
The standards referenced cover a whole host of wall coverings -
doesn't help clarify things.
My personal favorite is Wedi board. It's very easy to work with, it's
light and it's waterproof. There are also a bunch of different backer
boards, such as Durock, Wonderboard, Hardiboard, DensShield, Fiberock,
Do some more research on what you have. Unless there is another
product also called Gridmarx that is very water resistant, don't use
what you have.
A) The term 'concrete board' will confuse some people. The normal
name for the type of product you are referring to is a cement backer
B) Regular mortar is not used in a shower installation unless you are
doing a mud job. Again, the term will confuse some people. The OP
should just use the thinset he has for embedding the fiberglass mesh
tape covering the joints, and for setting the tile.
C) Why are you responding to my post instead of the OP's?
He states he's replacing a section, and seems to be detail oriented,
so he probably wants to match what's there.
He could use anything for spacers horizontally, vertical isn't much of
a problem to eyeball.
The other problem with thin grout lines can be filling the space all
the way to the substrate. An unsanded grout of lighter than usual
consistency would be my choice.
My theory is that most modern grout jobs fail due to failing to dampen
the joints before grouting, followed by failing to fill the joints,
and/or poor basic construction.
Which brings me to failed grout. The only reason I know of that grout
should fail is excessive flex of the substrate. In that case, no
grout job is going to last.
Any such major tile repair should be carefully evaluated against
complete replacement, and I wouldn't suggest the former be tackled by
homeowners, except that the chance of finding anyone more qualified is
There are tons of little tricks a "real" tile mechanic employs that
nobody told the clerk at HD. In this example it might be beating in
the new tile from a base on the existing tile, or recessing the new
substrate a hair and building it up with thinset to make it all come
out flush, or washing out the corner joints just a hair to leave a
little more room for caulk, if you think it's necessary.
All depends on your expectations of the finished product, I guess. A
good tile job is expensive, a homeowner can get comparable results
with due diligence.
Right. I didn't address that and I should have. I should also have
mentioned that unless you have the exact same tile from the same
manufacturer the tile will probably not match exactly. If it's a
little bit small you can get away with it, but if it's a little bit
big and the OT (original tiler) just butted the tile against each
other there will be a problem.
I like the round-square-round toothpicks as spacers. I also like to
chew on them. ;)
Or using too much water when cleaning off the excess grout.
I usually point people to the John Bridge tile forums. Lots of good
information and advice over there.
On Sun, 24 May 2009 18:30:02 -0700 (PDT), muzician21
Bad move. Premix thinset and "blue board" are not intended for wet
applications. For this application regular thinset and "hardibacker",
or equivalent, is a must. Neither are difficult to use and will last.
As others have said, if the tiles have the bumps on the edges spacers
aren't required. I'd use them anyway.
Since he didn't tell you that "blue board" was a waste of time and
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