Best answer

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.

Answered by: Avius Date created: Jun 23, 2022

Do I need to seal cement board before tiling?

Asked By: womp Date created: Jun 16, 2022

Contrary to popular thought, tile and grout are not waterproof, and some moisture will penetrate even if sealant is used. ... However, if you choose to use concrete backerboard, which is much stronger and more durable than gypsum board, a water vapor membrane must be placed underneath it or a sealant applied on top of it.

Answered By: The fourth bird Date created: Jun 19, 2022

Do I need a vapor barrier behind cement board in shower?

Asked By: Eric Guan Date created: Jun 12, 2022

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.

Answered By: Steve Date created: Jun 14, 2022

Do you need to waterproof cement board before tiling?

Asked By: Stephen Kennedy Date created: Jun 24, 2022

So, if you're looking for durability and strength, concrete backer-board will probably be your choice. First, you should provide a waterproof/resistant membrane against the wood studs before installing the concrete backer-board to protect the wood studs from moisture absorbed through the backer-board.

Answered By: Oriol Date created: Jun 25, 2022

Do you need to prime cement board before tiling?

Asked By: polkas Date created: Jun 23, 2022

Do I need to prime HardieBacker® board before I tile onto it? No. HardieBacker tile backerboard is ready to tile once installed, just wipe down with a damp sponge to remove any dust prior to tiling.

Answered By: Daniel Kivatinos Date created: Jun 26, 2022

Do you have to seal cement board before tiling?

Asked By: sdgfsdh Date created: Jun 13, 2022

Contrary to popular thought, tile and grout are not waterproof, and some moisture will penetrate even if sealant is used. ... However, if you choose to use concrete backerboard, which is much stronger and more durable than gypsum board, a water vapor membrane must be placed underneath it or a sealant applied on top of it.

Answered By: Andrew Eckart Date created: Jun 14, 2022

Do you need to waterproof cement board in a shower?

Asked By: Mahade Walid Date created: Jun 08, 2022

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.

Answered By: Ran Turner Date created: Jun 10, 2022

Is concrete block waterproof?

Asked By: Litar Date created: Jun 18, 2022

Waterproofing Concrete Block Foundations. Concrete blocks and cinder blocks are much more permeable to water and water vapor than poured concrete. ... Block foundation walls will provide only a weak barrier against capillary water seepage and water vapor.

Answered By: Grr Date created: Jun 19, 2022

Do I need to waterproof cement board in shower?

Asked By: damnever Date created: Jun 15, 2022

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.

Answered By: ehab Date created: Jun 16, 2022

How do you waterproof a flat concrete roof?

Asked By: Wookie88 Date created: Jun 18, 2022

Step 1 - Clean Your Roof. In order to successfully seal your roof, you first need to start with a clean surface. ... Step 2 - Carry Out Minor Repairs. ... Step 3 - Use Seam Tape. ... Step 4 - Coat With Primer. ... Step 5 - Spray on a Vapor Barrier.

Answered By: tscizzle Date created: Jun 21, 2022

Do you need to seal a concrete floor before laying laminate?

Asked By: samoz Date created: Jun 19, 2022

You don't need to seal a concrete floor before installing laminate; however, to prevent moisture from the concrete floor from affecting your laminate, install a vapor barrier of polyethylene film. Install this barrier even if the concrete subfloor is covered by vinyl, linoleum, terrazzo or ceramic tile.

Answered By: Timothy Rylatt Date created: Jun 20, 2022

Related Question Answers

DmitryBoyko

Professor

What do you put on concrete floor before laminate?

Begin installation by laying a plastic vapour barrier (minimum 6 mm thick) or any other manufacturer-recommended barrier on the concrete subfloor to prevent moisture from reaching the laminate flooring. Use vinyl tape to secure the barrier and keep it from coming out.

deltaskelta

Professor

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).

jondavidjohn

Professor

Do you need 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.

Strom

Professor

Do you need green board behind cement board?

Because cement board can be used either for floors or walls, the surface below the cement board will vary: ... In such wet areas, never install cement board directly over drywall or green board. Instead, first, remove the existing surface material, then install the cement board over the studs and membrane, as applicable.

Spoike

Professor

What 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..

adamk

Professional

Do you put cement board under a shower pan?

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.

Adam Matan

Professional

What can I use instead of cement board?

Glass mat gypsum board is a better choice. Sheets of glass mat gypsum are made from water-resistant silicone-treated gypsum, reinforced on both sides by fiberglass mats. DensShield is one common brand. It is easier to cut than cement board, it is mold resistant, and it has a built-in moisture barrier.

Sriram Sakthivel

Professional

Can I pour concrete around cast iron pipe?

You could just add a couple inches of sand, enough to handle the vapor barrier and then cover the pipe with a couple layers of plastic or roofing material and place the concrete right over the pipe.

David Hedlund

Professional

Can 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.

Billy Moon

Professional

Can you put cement board over tile?

Cement board forms a durable, stable base for tile, and it has no organic materials (unlike drywall, greenboard, or plywood) so it is not prone to mold, rot, shrinkage, or decomposition due to moisture. Ceramic tile laid over cement board is one of the most durable floor or wall surfaces you can install.

Irfan wani

User

Can 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..

Jeremy Thompson

User

How do you fill gap between cement board and tub?

Technically, after the tile is installed over the backer board that gap between it and the tub ledge should be filled with an ASTM C920 sealant (caulking e.g. silicone). Although some say you should have weep holes along this gap so any water behind can weep out into the tub.

Gama11

User

How do you install moisture barrier under concrete slab?

Most exterior slabs do not need a vapor barrier. ... In general, place the concrete slab directly on top of the vapor barrier, with the subbase below. ... The vapor barrier can be placed under the subbase, if the building is closed in when the dry subbase material is placed.More items...

Sobrique

User

Can 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..

xgqfrms

Guest

Do I need a vapor barrier between concrete and laminate flooring?

It is rolled out between the actual laminate flooring planks and the subfloor.

Very often, particularly in a below-grade installation on a concrete basement floor, a vapor barrier is recommended in addition to the underlayment.

That vapor barrier would go between the subfloor and the underlayment..

Tony Stark

Guest

Do I need a vapor barrier between concrete and wood flooring?

Despite a successful moisture check and the presence of an underground moisture barrier, you still need additional protection from water vapor before laying a wood floor. Sheets of 6-mil thick polyethylene plastic, overlapped with seams taped, is one means of providing that moisture barrier.

Rahul Tripathi

Guest

Do I need to prime cement board before tiling?

Do I need to prime HardieBacker® board before I tile onto it? No. HardieBacker tile backerboard is ready to tile once installed, just wipe down with a damp sponge to remove any dust prior to tiling.

Dupinder Singh

Guest

Do plaster walls need insulation?

If your historic house has original plaster walls, you should not blow insulation into the exterior walls. Old houses with plaster walls have no vapor barrier under the plaster to stop moist air from saturating the insulation. Instead, plaster walls are designed to allow the free exchange of air and moisture.

arik

Guest

Do 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..

Ben

Guest

Do 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.

Donald Duck

Guest

Do 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..

Zaw

Guest

Do you need to waterproof cement board?

Although most backerboards currently available won't fall apart when exposed to moisture and are somewhat water-resistant, they aren't waterproof. To prevent moisture from seeping through to the wood or metal studs beneath the tile, a barrier or sealant must be used on porous materials.

Ben Bolker

Guest

Does 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.

Jonathan Clark

Guest

Should you seal concrete before laying laminate?

You don't need to seal a concrete floor before installing laminate; however, to prevent moisture from the concrete floor from affecting your laminate, install a vapor barrier of polyethylene film. Install this barrier even if the concrete subfloor is covered by vinyl, linoleum, terrazzo or ceramic tile.

The Unfun Cat

Guest

Why do you put cement in a tree?

Excess water can result in wood rot. In the past, tree cavities were simply filled with cement in an effort to block up the wound. ... When a tree is wounded, it uses its natural defense of compartmentalization to create a barrier between the wound and the rest of the tree.

Kris

Guest

Do 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.

Christos Panagiotakopoulos

Guest

Do 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.

Dai

Guest

How do I stop moisture in my concrete floor?

Methods Used to Stop Moisture in Concrete FloorsLow-permeance Vapor Barrier or Retarder.

A Low-permeance vapor Barrier or retarder can effectively keep below-slab moisture from reaching the flooring system.

...

Allow Natural Drying of Concrete Slab.

...

Keep Excavation Free of Water..

Salvador Dali

Guest

Do you need underlay on concrete floors?

Most sub-floors will be either wood or concrete. Concrete bases need an underlay with a moisture barrier, a damp proof membrane (DPM) or a separate barrier to protect the floor from damp. If the sub-floor is wooden the choice of underlay will depend on what is being laid on top.

aromero

Guest

Is a vapor barrier necessary behind cement 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. ... You should NOT place a vapor barrier BEHIND the backer board.

Bill Karwin

Guest

Should I put plastic behind cement board?

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.

fastcodejava

Guest

Does 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.”

Marcus Lind

Guest

Do I need insulation under a concrete floor?

Creating an insulation layer and a vapor barrier between the concrete slab and the ground beneath it is the best practice in insulating basement floors.

The insulation barrier will help keep warm air in, and the vapor barrier will keep unwanted moisture out..

Joakim Danielson

Guest

Do 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.

Giorgos Myrianthous

Guest

Should 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.

Moe

Guest

Should 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.

Hitmands

Guest

What 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.

ernest_k

Guest

What is the best insulation for under a concrete slab?

Applying a bead of polystyrene-compatible caulk or mastic to the top of the insulation board minimizes water infiltration behind it. For under-slab applications, the rigid foam insulation typically should be installed over a gravel base, with a poly vapor diffusion retarder between the gravel and insulation.

Josh Buhler

Guest

Is cement board the same thickness as drywall?

Whereas drywall comes in 4-by-8 sheets, cement board comes in 3-by-5 sheets. ... The smaller dimensions of cement board make the installation of it on large walls more difficult, but cement board panels fit vertically in 3-foot wide showers, or horizontally behind a standard 5-foot bathtub.

AndiDog

Guest

What is the purpose of a vapor barrier under concrete slab?

The use of a vapor barrier (more accurately termed a vapor retarder), having a water vapor permeance of less than 0.3 perm is frequently used to retard the flow of moisture through the slab. These vapor retarders are typically polyethylene or polyolefin sheeting materials.

Joel Coehoorn

Guest

How do you insulate lath and plaster walls?

Treat Your Gutted Walls Like New Construction When you have gutted your walls, install fiberglass batting, foam insulation or dense-pack cellulose insulation from the inside. Place a 4-mil plastic sheeting vapor barrier over all three of these types of insulations.

mcsoini

Guest

Is concrete a Vapour barrier?

Actually, no. Air barriers need to be continuous and free from holes, but vapor barriers do not need to be. Lots of vapor moves by air movement, not a heck of a lot of vapor moves by vapor diffusion. The concrete slab is the air barrier, and the ripped and torn and punctured polyethylene sheet is the vapor barrier.

Eric O Lebigot

Guest

Do you need a vapor barrier under concrete driveway?

The application of vapor barrier in exterior concrete is unnecessary due to the fact that water penetration does not matter. Any slab on grade that is enclosed and on the interior of a building should have a vapor barrier installed prior to pouring concrete, especially if flooring will be applied.

mah

Guest

Do you put plastic under concrete slab?

In California they place sand between slabs and plastic vapor barriers—in Florida they don't. Almost everywhere (except “California”) that slabs are placed on the ground—a plastic sheet—a vapor barrier—is located directly under the concrete slab and on top of the ground (Photograph 1).

MrFlick

Guest

Do 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.

aga

Guest

Where 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.

Thorbjørn Ravn Andersen

Guest

Do you need to seal cement tiles?

Like natural stones, cement tiles are porous and therefore need to be sealed to avoid staining. Penetrating sealers coat the cement particles in the tile making it less likely they will retain stains. Topical sealers create a barrier on the surface of the tile so that stains do not reach the cement.

Prashanth Sams

Guest

Do cement tiles need to be sealed?

Like natural stones, cement tiles are porous and therefore need to be sealed to avoid staining. Penetrating sealers coat the cement particles in the tile making it less likely they will retain stains. Topical sealers create a barrier on the surface of the tile so that stains do not reach the cement.