Best answer
Once the subfloor of proper thickness is properly installed then you can apply cement board directly to the subfloor material. ALL CEMENT BOARDS MUST be installed in a fresh bed of thinset. ... If you want the cement board under the shower tray then do so - doesn't matter.
Do I need a vapor barrier behind cement board in shower?
Moisture barriers stop that water or vapor from getting any farther and potentially rotting your studs, the drywall or greenboard installed behind the enclosure. They are required beneath your shower pan and behind your shower walls.
Do you have to waterproof cement board?
Most concrete backer-boards on the market today are not water-resistant, but all are waterproof. Since many people confuse the terms, it is a common misconception that this is the best material for use inside a shower or tub area.
Can you paint cement board in shower?
Can you paint cement board in shower? Not likely. but Hardie backer board's official installation tutorial says it can be finish with paint. Use the backer board on the tiled part, and use the moisture resistant drywall on the rest.
Do you have to use thinset under cement board?
No Thinset underneath the backer board “The thinset goes ON TOP of the cement board to stick the tiles!” ... Cement board is a different product and it needs to be installed in its own way. Additionally, screws don't take the place of thinset either.
Do you need to waterproof cement board in a shower?
Cement board is not waterproof. Hardibacker is not waterproof. Tile and grout are not waterproof. Cement board will not fall apart when exposed to water.
Do I need to waterproof cement board in shower?
Here's what the TCNA handbook has to say about the matter: “A waterproof membrane or vapor retarder membrane must be specified to prevent moisture intrusion and protect adjacent building materials.” ~B412 Bathtub or shower with prefabricated receptor. Cement board or Fiber-cement board.
Can you use cement tiles in a shower?
The most common question is, "Can I use them in my shower or bath?" The answer is definitely, "Yes!" Cement tiles can also be used in wet areas such as the bathroom floor, shower floor, shower wall, steam room or sauna.
...
However, do not confuse encaustic cement tile with encaustic tile..
Do you need plastic behind cement board?
Their online instructions/diagrams show no use of a vapor barrier. You should, so that any moisture that gets behind the cement board runs into the tub or shower instead of into your wall cavity (causing rot or mold/mildew).
Do you need to put a vapor barrier behind cement board?
You should NOT place a vapor barrier BEHIND the backer board. Where, pray tell, would any such collected vapor/water go? Answer:There's nowhere proper for such moisture to egress. The current best practice is to place waterproofing OVER the backetboard and just UNDER the tile.
Is Thinset under cement board necessary?
Not only is thinset a critical component underneath cement board but the other critical component is the fasteners. And you won't have the fasteners if you are trying to install it over concrete.
Related Question Answers

EJBEAN
ProfessorWhat do you put behind cement board in shower?
Cement Board and a Liquid Membrane No plastic sheeting goes behind the cement board.
A liquid waterproofing membrane, such as RedGard or Hydro Ban, is applied to the cement board and allowed to cure.
Then, tile is installed over the membrane..

troelskn
ProfessorIs backer board the same as cement board?
Cement backer board is also called cement board, and it's the most commonly used backer board for all manner of ceramic and porcelain tiles. Made of cement and reinforced on the top and bottom with fiberglass, this waterproof backer board is generally used for tiled shower surrounds and floors in wet areas.

paxos1977
ProfessorCan you use cement board in a shower?
In showers, the standard substrate is tile backer, also called cement board or cement backer board. Ceramic and porcelain tile, more than almost any other surface material, needs a stable, flat, flex-free substrate. Even the slightest amount of movement in a building structure can telegraph to the tile and crack it.

Laurence Gonsalves
ProfessorCan I use concrete for shower pan?
Concrete is perfectly adequate, if not recommended, for use as the shower pan base for materials such as stone, tile or mosaic tile to be used as the finish surface (as long as there is a proper membrane between the concrete and any vulnerable surrounding material).

Jean
ProfessorCan you glue stone veneer to cement board?
What can I put stone veneer on for an interior application? For interior applications, stone veneer can be installed over cement board, drywall, and all of the above.

ARK1375
ProfessionalCan you put cement over silicone?
Yes, silicone will stick to cement board.
In fact I highly recommend that you use cement board such as 'Durock' as your backer board.
Use proper screws.
Such as the specific cement board screw..

Netwave
ProfessionalHow do you cement a toilet bowl?
HOW TO USE SAND & CEMENT TO SET A NEW TOILET PANPREPARE FOR THE MORTAR BASE. Carefully mark the outline of the area to be covered by the toilet pan. ... MIX THE SAND & CEMENT. Add one 20kg bag of Sand & Cement to a large bucket and add 3.5 litres of clean water. ... FORM A MORTAR BED. ... SET THE PAN ON THE MORTAR BED. ... FINISHING OFF.

erenon
ProfessionalCan you use cement board for shower walls?
Cement Board and a Sheet Membrane Kerdi can also be installed directly over standard drywall in a shower because, when installed correctly, it creates a continuous waterproof barrier..

Isac Moura
ProfessionalCan you use concrete in a shower?
Concrete is perfectly adequate, if not recommended, for use as the shower pan base for materials such as stone, tile or mosaic tile to be used as the finish surface (as long as there is a proper membrane between the concrete and any vulnerable surrounding material).

John Ruddell
ProfessionalDo I have to use cement board under Wall Tile?
In short, tile and grout are not inherently waterproof. ... Cement backer board is often used as a tile base on plywood or OSB subfloor. Cement backer board on concrete as a subfloor or underlayment is usually not recommended or needed. In most cases, you can apply tile directly to the concrete.

Guillaume Vincent
UserDo I need a shower pan liner on concrete floor?
JRC3 Member.
It will need to be lined or it will wick into the slab and studding.
The liner also makes the walls around the pan water-tight, that's why the liner normally goes up at least 3" above the pan behind the tile and backer material.
Moisture gets behind the wall tile and is eventually caught by the liner..

Gerry P
UserDo I need a shower pan on concrete floor?
You will have to ensure that there is no wax, oil, grease, or soap scum on the face of the concrete slab that could ruin or reduce the bond. After that, I recommend that you install a sloped shower pan to contain the shower water and prevent harmful organisms from becoming resident in the surrounding walls and floor.

Josh Habdas
UserDo you have to replace cement board under tile?
Undamaged cement backer board does not need to be replaced.
...
It is difficult to remove tile from a cement backer board, and even more difficult to avoid damaging the board in the process.
Since backer board is relatively inexpensive, it's not normally worth the time and labor it would take to remove the tile to save it..

Yves M.
UserDo you install cement board before shower pan?
The wallboard must be installed 1/8 inch above the shower pan. If the shower pan is not in place, the wallboard height must be guessed, which can lead to inaccuracies and an expansion gap that is too large or too small.

Konrad Dzwinel
UserDo you need a shower pan liner on concrete floor?
JRC3 Member. It will need to be lined or it will wick into the slab and studding. The liner also makes the walls around the pan water-tight, that's why the liner normally goes up at least 3" above the pan behind the tile and backer material.

Luis Miguel Mejía Suárez
GuestDo you need plywood under cement board?
The Surface Below the Cement Board Flooring: For ceramic tile floors, the cement board usually rests on a plywood subfloor (minimum 5/8-inch-thick exterior-grade plywood or OSB). ... In such wet areas, never install cement board directly over drywall or green board.

Fabrizio Valencia
GuestDo you need Thinset under cement board?
Not only is thinset a critical component underneath cement board but the other critical component is the fasteners.
And you won't have the fasteners if you are trying to install it over concrete..

GorvGoyl
GuestDoes cement board go over lip of shower pan?
The best approach when installing cement board or other tile backer around a tub is to keep the cement board out of the lip area.
Apply it to the wall with the bottom edge about 1/4 in.
above the lip of the tub.
...
Fill the gap between the tile and the tub with caulk..

hilberts_drinking_problem
GuestDoes cement board need to be sealed?
While you don't always need to seal backer board, it sometimes make sense to do so. If you are installing backer board in an area that will be subject to a great amount of moisture, like in a shower, then it makes sense to put a waterproofing sealer on it.

Niels
GuestCan I use cement board for shower floor?
Do not use cement board on its own. Your shower will leak and you will be tearing it out within a year.

Luchian Grigore
GuestDo I need cement board for kitchen backsplash?
But for a tile backsplash, if your wall is good and plumb, without any major ridges or problems, you don't always need to use a backer board, often you can just apply thinset to the walls and put your tiles in place.

duncan
GuestDo you put cement board under bathtub?
You don't need any cement board under the tub. It is far more important to have a sturdy layer of ply under the tub.

Naftali aka Neal
GuestDoes cement board in shower need waterproofing?
“A waterproof membrane or vapor retarder membrane must be specified to prevent moisture intrusion and protect adjacent building materials.” ~B412 Bathtub or shower with prefabricated receptor. Cement board or Fiber-cement board. Ceramic Tile. ... Consult local building code for moisture barrier requirements.”

Alessio Popovic
GuestCan you put footings under concrete slab?
edit - To put footings under the slab, you can cut holes wherever needed, excavate for footings (Sonotubes or concrete piers or similar) and then patch the concrete slab.

Adriano Carneiro
GuestDo I need plywood under cement board?
Because cement board can be used either for floors or walls, the surface below the cement board will vary: Flooring: For ceramic tile floors, the cement board usually rests on a plywood subfloor (minimum 5/8-inch-thick exterior-grade plywood or OSB).

Alireza
GuestDo you have to put Thinset under cement board?
No Thinset underneath the backer board “The thinset goes ON TOP of the cement board to stick the tiles!” ... Cement board is a different product and it needs to be installed in its own way. Additionally, screws don't take the place of thinset either.

Paul H
GuestShould I put cement board under tub?
You don't need any cement board under the tub. It is far more important to have a sturdy layer of ply under the tub.

Florent Morselli
GuestShould I put Thinset under cement board?
Embed the cement board in latex-modified thin-set mortar The main reason for using thin-set between the cement board and the subfloor isn't as much for bonding as it is for even, void-free cement board support throughout the floor. ... Then spread thinset mortar with the flat side of a 1/4-in.

pyon
GuestShould you put a vapor barrier behind cement board?
You still need a vapor barrier with cement board, although in this case the barrier can go behind the board. Cement board is heavy enough and breathable enough to take the moisture without a problem. By having the vapor barrier behind the cement board you stop the moisture going further into the wall.

Zeitounator
GuestWhat do you put on seams of cement board?
Use special mesh tape on seams Cut drywall to fill in between the existing wall or ceiling and the cement board. Screw the drywall to the studs. Cover all of the corners, joints and seams, including the joint where drywall and cement board meet, with the fiberglass mesh tape.

Pascal
GuestIs Durock cement board non-combustible?
This DUROCK® cement board is a non-combustible, water and mold-resistant panel designed for use under tile, in shower areas, and readily applied over ...

instanceof me
GuestDo I need cement board for shower ceiling?
It can be, but it's not really necessary. You can tile directly to drywall in any dry area. If your doors go all the way to the ceiling, you might consider cbu verses any kind of drywall on the ceiling, otherwise, it is considered a dry area.

Collin Jackson
GuestCan you use concrete mix for shower pan?
The best mortar for a shower pan is a mix of standard cement mix with sand and Portland cement.
...
A mortar mix provides the best base because it's very shapable, allowing the owner to fit whatever type of shower or bath pan into the supportive base..

miku
GuestCan you caulk cement board in shower?
In the event the caulk seal between the bottom row of tile and the tub/shower fails, water can get behind the tile. If the backer board is touching this ledge, it will readily soak up this water like a sponge. ... Then, before installing the tile, apply a bead of pure silicone caulk between the backer board and the ledge.

EpicPandaForce
GuestCan you make a shower pan with cement board?
Do not use cement board on its own.
Your shower will leak and you will be tearing it out within a year..

Pekka
GuestDo you have to glue down cement board?
You cannot put a cement backer board over that. You need to put a layer or plywood, minimum 5/8 IIRC, over those boards, then mortar the backer to the plywood. Those 1x8 boards won't give a solid foundation and will flex. Over time, that will cause tile to pop loose or crack.

Adam Matan
GuestDo you need a shower liner on concrete floor?
JRC3 Member. It will need to be lined or it will wick into the slab and studding. The liner also makes the walls around the pan water-tight, that's why the liner normally goes up at least 3" above the pan behind the tile and backer material. Moisture gets behind the wall tile and is eventually caught by the liner.

Chris
GuestHow thick does a concrete shower pan need to be?
As a general rule, a shower curb foundation is 3 to 4 inches thick and 4 to 6 inches tall, with finish material adding to these dimensions..

YPCrumble
GuestWhat kind of cement do you use for a shower pan?
Floor Mud QUIKRETEQUIKRETE® Floor Mud (No. 1548-81) is a Portland cement based underlayment mortar designed for leveling travertine, slate and marble floor tile, and for shower pan applications.

Aaronaught
GuestWhat kind of concrete do you use for a shower pan?
The best concrete mix for shower pans is made by Quikrete.
They make two products, the first is called Floor Mud, the 2nd is their Sand/Topping mix.
Both work great for building a shower pan..

tokland
GuestWhere do you put cement board in a bathroom?
Cement backer board is mainly used as a sub-surface for tiling. Cement backer board is often used as a tile base on plywood or OSB subfloor. Cement backer board on concrete as a subfloor or underlayment is usually not recommended or needed. In most cases, you can apply tile directly to the concrete.

web-tiki
GuestDo you have to put cement board under tile?
In short, tile and grout are not inherently waterproof. ... Cement backer board is often used as a tile base on plywood or OSB subfloor. Cement backer board on concrete as a subfloor or underlayment is usually not recommended or needed. In most cases, you can apply tile directly to the concrete.

fedorqui 'SO stop harming'
GuestDo I need cement board under floor tile?
If you're working over a wood subfloor, cement board is the right choice for your tile base. ... Because plywood expands and contracts beneath the ceramic tile, grout and tile failure (loose tiles and cracked, crumbling grout) is just a matter of time.

Thiar
GuestDo you need to waterproof cement board in shower?
Cement board is not waterproof. Hardibacker is not waterproof. Tile and grout are not waterproof. Cement board will not fall apart when exposed to water.

wOxxOm
GuestCan I just screw down cement board?
Put thinset beneath your backerboard. And put your dog out. Once you have the area fully covered with thinset you can lay your backerboards into the bed of thinset and screw it down. DO NOT use drywall screws!

BoarGules
GuestDo you need to use thinset under cement board?
Not only is thinset a critical component underneath cement board but the other critical component is the fasteners. And you won't have the fasteners if you are trying to install it over concrete.

andilabs
GuestHow do you remove a toilet from a concrete floor?
Use a small hammer and chisel to carefully crack the back of the pan near the joint to the waste pipe. This will separate the pan spigot from the rest of the pan. Then smash the pan away from the pipe with a bigger hammer and clean off any cement on the floor.

Paul Verest
GuestHow high should cement board be in shower?
Start installing your boards a quarter inch above the floor, tub, or shower board and caulk accordingly. 2. Fasten cement board with specified nails or screws, a maximum of 8” on center at all supports.

rap-2-h
GuestShould I put cement board under tile?
If you want to replace an old, cracked tile floor or other type of flooring with new ceramic tile, it's absolutely imperative that you create a solid setting base for the new tile. If you're working over a wood subfloor, cement board is the right choice for your tile base.

chemamolins
GuestHow many bags of cement do I need for a shower pan?
Building a mud shower is really hard work. This one required 300 lbs (dry) of cement and sand. Another 300 lbs of cement board for the walls. More hundreds of lbs of tile, thinset and grout.