Do I need plywood under cement board?

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.

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).

It's best to use the cement board screw, but a deck screw will do just fine. ... Use screws designed for cement board like Rock-On screws. They start easier than drywall screws in CBUs. They're easier to use, don't rust as easily and hold better.

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.

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.

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.

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.

Both 1/4- and1/2-inch cement board are appropriate for floors. To install cement board on floors, cement board manufacturers mandate a 5/8-inch plywood subfloor or OSB underlayment.

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.

Plywood is economical to use for wall and floor forms; however, plywood used for this purpose should be made with waterproof glue and marked for use in concrete forms. Plywood is warp-resistant and can be used more often than other lumber.

Nearly all types of plywood panels can be used in concrete-forming, from common roof and wall sheathing to sanded panels.

No. You will need actual subfloor (3/4 osb or ply) below the cement board to support it. And you'll only need cement board if you're laying tile. Cement board alone will be far to soft, among other problems.

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.

Natural stone veneer is heavy and should not be installed over drywall; cement backerboard or masonry applications are recommended.

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.

Undamaged cement backer board does not need to be replaced.

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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..

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.

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..

Floors of concrete or compressed fibre cement sheet flooring are required to be water resistant. Timber floors including particleboard plywood and other materials require waterproofing of the whole floor. Walls are to be water resistant and junctions to be waterproofed.

If it's a cement board, you need a vapor barrier, because cement retains moisture, which means the wood next to it is always damp.

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.

It will bond to drywall, plaster, vinyl cove base, polystyrene, polyurethane foam covings, PVC (rigid plastic), stainless steel, glass, wood, plywood, stone, brick, concrete, chip board, ceramics, foam board, cork, and carpet.

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.30 Sep 2015

Do not use cement board on its own. Your shower will leak and you will be tearing it out within a year.

Half-inch cement backer board is ideal for most tiling jobs, including walls, floors, countertops, and ceilings.

For flooring, the backer board should be installed over a 5/8-inch thick OSB or plywood base..

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.

Position each piece of backer board in the thin-set, press in place, and attach using special backer board screws on the spacing recommended by the backer board manufacturer.

Cover the joints in the backer board with fiberglass tape embedded in thin-set adhesive and allow to set before tiling..

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.

If you're working over a wood subfloor, cement board is the right choice for your tile base. No matter what you're told at a home center, it's not a good idea to install tile directly over plywood, especially in a damp area like a bathroom.

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.

Cement backerboard is perfect for wet and high-moisture applications, such as kitchens and bathrooms, where you'll typically install the panels over a moisture-resistant drywall or plywood sheathing. Cement backerboard mounts to metal stud framing using the same procedure as wood framing.

Undamaged cement backer board does not need to be replaced. If tile has not been attached directly to the backer board, and it has not been dented or punctured, it can be reused without any special preparation.

A self leveling compound can be applied to most types of subfloor materials. You can apply self leveling compound to plywood, osb, concrete, cement board, hardibacker and many other types of subfloor materials. You can also use self leveling compounds when installing tile over top of an existing tile installation.

Both 1/4- and1/2-inch cement board are appropriate for floors. To install cement board on floors, cement board manufacturers mandate a 5/8-inch plywood subfloor or OSB underlayment.

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.

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.

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 ...

Do I need a DPM under laminate flooring? Simply put yes. In order to prevent damp rising through the concrete floor and causing issues, a DPM should be used under all final floor types including wood flooring, laminate, vinyl and floor tiles.

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.

Scoop up thinset on the flat edge of a 1/4-inch, square-notched trowel and spread the thinset across the plywood. Cover an area large enough to place the first backer board sheet. Apply another layer of thinset over the first, using the square-notched edge of the trowel.

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.

Cement is actually a very porous material and can easily absorb water. Therefore, any concrete that may come into regular contact with water, such as under tile or for a pool, will need to be waterproofed. If cement is not waterproofed, it can cause issues with the mortar used between the tiles.

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.

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.

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.

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.

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.

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.

Well if you go by the spec a bag of Multi and Board finish will cover 10.25-75 m2 at a coverage of 2mm on Plaster board. As the manufacturer will tell you this is, of course, just a guide.

Cement backerboard is more stable than plywood in high humidity and other wet environments. It won't swell and buckle the way that plywood does, so it's safe to use in mudrooms and bathrooms where things like spills and puddles are normal, as well as in areas with high levels of moisture in the air.