Is a vapor barrier necessary 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.

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.

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..

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.

Also, cement board typically has a label or manufacturer sticker on the front of the board. The back of cement board is plain, has no manufacturer-defining stickers and is void of the front-featured grid. Always install cement board with the grid facing out.

In either case you use whatever tools are necessary to get it back to a clean subfloor. The second way to interpret your question is, after you've removed and cleaned off the old floor, can you install new tile without backer board. Well yes.

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. Manufactured veneer stone is another use for cement backer 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.

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.

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.

Yes, concrete can be sanded in order to get a smooth and consistent surface. It is actually necessary if you want to achieve one of the three typical concrete finishes that are also introduced in this article. Normally, large surfaces are sanded with hand-held or walk-behind concrete sanders or grinders.

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.

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...

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..

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..

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.

plaster is not a vapor barrier, so any odors in the walls can get in. it's good for the longevity of the plaster since it can breathe (if it gets wet, it can dry, for instance), but it won't keep the odors out.

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..

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.

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.

Anatomy of a Concrete Floor This layer is covered with a vapor barrier sheet that prevents moisture from moving up into the concrete. A welded wire fabric mesh sheet is then placed over that in order to aid with adhesion. Finally, the concrete slab is poured directly onto these layers.

Plastic drainage mats, or dimple mats, allow air to circulate under the flooring and provide a moisture barrier.

They also provide an insulating layer of air that separates the floor from cold concrete, reducing the potential for moisture damage from condensation or water vapor migrating through the concrete..

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 weight of one square meter of a standard fiber cement board 8 mm thick is 13,2 kilograms.

Here's what happens: When the concrete is heated, the cement inside becomes dehydrated, losing some of its water as vapor. That water vapor begins moving away from the source of the heat, but becomes trapped inside the structure of the concrete.

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.

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Allow Natural Drying of Concrete Slab.

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Keep Excavation Free of Water..

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.

“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.”

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..

Linda CottinStep 1: For holes larger than 1/2-inch in diameter, use a carton knife or carbide-tipped tool to cut a V-shaped groove behind the edges of hole. ... Step 2: Use a clean, damp sponge to wipe down the area to be patched.Step 3: Mix up a small amount of thin-set mortar following the manufacturer's instructions.More items...•

The back of cement board is plain, has no manufacturer-defining stickers and is void of the front-featured grid. Always install cement board with the grid facing out.

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.

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.

Hence the question “Is cement board waterproof?” Well, here's what some manufacturers have to say about waterproofing: PermaBase (National Gypsum): PermaBase PLus is not a water barrier. ... Durock (USG): “If waterproofing is desired, use USG Durock™ Tile Membrane or USG Durock™ Brand Waterproofing Membrane.”

Contrary to popular thought, tile and grout are not waterproof, and some moisture will penetrate even if sealant is used.

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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..

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.

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.

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.

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.

Yes, concrete can be sanded in order to get a smooth and consistent surface. It is actually necessary if you want to achieve one of the three typical concrete finishes that are also introduced in this article. Normally, large surfaces are sanded with hand-held or walk-behind concrete sanders or grinders.

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.

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).

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.

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.

9 ways to effectively reduce garage condensationControl your garage's temperature. ... Use a vapor barrier. ... Dry your wet vehicle off after parking it in the garage. ... Check your ventilation. ... Inspect your drainage. ... Apply a floor coating. ... Install a dehumidifier. ... Get rid of that old garage fridge or freezer.More items...

Concrete slabs are not impervious to water. In fact, given the right environmental conditions, the floor slab can transmit gallons of water into the living space as vapor, and in extreme cases, actually show ponding water. ... The pre-construction solution is to use an underslab vapor barrier.

Some people like to add a bit more rubber cement to the plug after it is in, but it is not necessary. In fact, you can plug a tire without the rubber cement, it just makes for a quicker bond. While it is possible to put a plug into the side wall, it will generally not hold.

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.