Mortar Under Acrylic Shower Base
 

I'm re-doing a shower using an acrylic/fiberglass base. The
instructions say to put "mortar cement" under the base. Makes sense,
there were lumps of grey rock-like substance under the one I pulled
out. Problem is, I can't translate "mortar cement" into anything I
can buy at HD, etc.

My searches tell me to use the same mortar as laying bricks, or to NOT
use the same stuff, use regular concrete mix, use regular mix with
sand added, don't use regular mix as it will wreck the plastic, etc
etc etc.
I think I know less now than when I started.

Can somebody tell me what it should say on the bag at the building
center? Brand names are fine, if it isn't available around here at
least I can ask for equivalent product.

Thanks,
Red

Mortar Under Acrylic Shower Base
 

red wrote:
I'm re-doing a shower using an acrylic/fiberglass base. The
instructions say to put "mortar cement" under the base. Makes sense,
there were lumps of grey rock-like substance under the one I pulled
out. Problem is, I can't translate "mortar cement" into anything I
can buy at HD, etc.

My searches tell me to use the same mortar as laying bricks, or to NOT
use the same stuff, use regular concrete mix, use regular mix with
sand added, don't use regular mix as it will wreck the plastic, etc
etc etc.
I think I know less now than when I started.

Can somebody tell me what it should say on the bag at the building
center? Brand names are fine, if it isn't available around here at
least I can ask for equivalent product.

Thanks,
Red

You are looking for "Thin-set Mortar" and you will find it in the tile
section, as it is used to set tiles.

Mortar Under Acrylic Shower Base
 

EXT wrote:
red wrote:
I'm re-doing a shower using an acrylic/fiberglass base. The
instructions say to put "mortar cement" under the base. Makes sense,
there were lumps of grey rock-like substance under the one I pulled
out. Problem is, I can't translate "mortar cement" into anything I
can buy at HD, etc.

My searches tell me to use the same mortar as laying bricks, or to NOT
use the same stuff, use regular concrete mix, use regular mix with
sand added, don't use regular mix as it will wreck the plastic, etc
etc etc.
I think I know less now than when I started.

Can somebody tell me what it should say on the bag at the building
center? Brand names are fine, if it isn't available around here at
least I can ask for equivalent product.

Thanks,
Red

You are looking for "Thin-set Mortar" and you will find it in the tile
section, as it is used to set tiles.


I'm no expert, but I think not. Thin-set is pretty runny. All the
mortar-bedded shower bases and plastic tubs I ever saw go in were bedded
in plain old mortar mix. You definitely don't want concrete, lest a
stone poking up worry its way through the shower base.

ISTR on TOH a year or two back, they showed people using gypcrete, and
even a plastic foam that set up rock hard, instead. It doesn't need that
much strength like a sidewalk would, it is just to keep the shower base
from flexing as people stand and move in it.

--
aem sends...

Mortar Under Acrylic Shower Base
 

aemeijers wrote:
EXT wrote:
red wrote:
I'm re-doing a shower using an acrylic/fiberglass base. The
instructions say to put "mortar cement" under the base. Makes
sense, there were lumps of grey rock-like substance under the one
I pulled out. Problem is, I can't translate "mortar cement" into
anything I can buy at HD, etc.

My searches tell me to use the same mortar as laying bricks, or
to NOT use the same stuff, use regular concrete mix, use regular
mix with sand added, don't use regular mix as it will wreck the
plastic, etc etc etc.
I think I know less now than when I started.

Can somebody tell me what it should say on the bag at the building
center? Brand names are fine, if it isn't available around here
at least I can ask for equivalent product.

Thanks,
Red

You are looking for "Thin-set Mortar" and you will find it in the
tile section, as it is used to set tiles.


I'm no expert, but I think not. Thin-set is pretty runny. All the
mortar-bedded shower bases and plastic tubs I ever saw go in were
bedded in plain old mortar mix. You definitely don't want concrete,
lest a stone poking up worry its way through the shower base.

ISTR on TOH a year or two back, they showed people using gypcrete, and
even a plastic foam that set up rock hard, instead. It doesn't need
that much strength like a sidewalk would, it is just to keep the
shower base from flexing as people stand and move in it.

Thin-set is only as runny as you make it by adding too much water. To bed a
shower base, you need something that is soft enough to conform to the bottom
shape so that it supports the base completely when it hardens. There will
not be much room under the base, so this is where thinset comes in, as it
will harden and maintain its strength even in very thin layers. If a thick
bedding is needed, then masonry mortar "may" work

Mortar Under Acrylic Shower Base
 

On Thu, 05 Nov 2009 19:17:11 -0500, aemeijers
wrote:

EXT wrote:
red wrote:
I'm re-doing a shower using an acrylic/fiberglass base. The
instructions say to put "mortar cement" under the base. Makes sense,
there were lumps of grey rock-like substance under the one I pulled
out. Problem is, I can't translate "mortar cement" into anything I
can buy at HD, etc.

My searches tell me to use the same mortar as laying bricks, or to NOT
use the same stuff, use regular concrete mix, use regular mix with
sand added, don't use regular mix as it will wreck the plastic, etc
etc etc.
I think I know less now than when I started.

Can somebody tell me what it should say on the bag at the building
center? Brand names are fine, if it isn't available around here at
least I can ask for equivalent product.

Thanks,
Red

You are looking for "Thin-set Mortar" and you will find it in the tile
section, as it is used to set tiles.


I'm no expert, but I think not. Thin-set is pretty runny. All the
mortar-bedded shower bases and plastic tubs I ever saw go in were bedded
in plain old mortar mix. You definitely don't want concrete, lest a
stone poking up worry its way through the shower base.

I used thinset, mixed to a "low slump" consistancy and just "worked"
the base in.

ISTR on TOH a year or two back, they showed people using gypcrete, and
even a plastic foam that set up rock hard, instead. It doesn't need that
much strength like a sidewalk would, it is just to keep the shower base
from flexing as people stand and move in it.

Mortar Under Acrylic Shower Base
 

"red" wrote in message
...
I'm re-doing a shower using an acrylic/fiberglass base. The
instructions say to put "mortar cement" under the base. Makes sense,
there were lumps of grey rock-like substance under the one I pulled
out. Problem is, I can't translate "mortar cement" into anything I
can buy at HD, etc.

My searches tell me to use the same mortar as laying bricks, or to NOT
use the same stuff, use regular concrete mix, use regular mix with
sand added, don't use regular mix as it will wreck the plastic, etc
etc etc.
I think I know less now than when I started.

Can somebody tell me what it should say on the bag at the building
center? Brand names are fine, if it isn't available around here at
least I can ask for equivalent product.

Thanks,
Red

My base flexed a bit when it was on the cement floor. Called the
manufacturer and he recommended using expandable foam--the kind that is used
to seal leaks etc. and comes in a spray can. I inserted the small nozzle
extension in all the open spaces under the base and let it fill until it
started coming out. Let it harden and then cut off all the stuff that had
expanded outside of the base. It's been several years now without a problem
and the base is solid--no movement at all.
MLD.

I've also taken the advice of a manufacture to use spray foam. WHAT A MISTAKE. I set a 200lb cultured marble bathtub with it. I placed 3-400 lbs of tools in the tub after I sprayed the foam. The next day, even with all the weight, the tub had risen 2" off the floor from the foam expanding underneath. You don't want a 1/2" thick bed underneath the pan, just something to stabilize it. Thinset mortar is the way to go. If you are concerned about not filling the voids in the pan, flip it over and fill them with thinset, let them dry, and then set the pan in a thinset mortar bed. Cement and the pan will not react, don't use plastic on the pan side. I use tyvek for the floor only because it's clean. Staple the snot out of it when you put it on the floor. 1/8-1/4" of mortar is all that's needed for a good set, the pan is essentially a large tile.