plastic behind cement board with waterproofing is essentially suspenders when you already have a belt. the waterproofing is also a vapor retarder so if the red guard or kerdi product is continuous, lapping corners and all, the plastic will be unnecessary.
What is the purpose of the plastic behind cement board?
plastic behind cement board with waterproofing is essentially suspenders when you already have a belt. the waterproofing is also a vapor retarder so if the red guard or kerdi product is continuous, lapping corners and all, the plastic will be unnecessary.
Do I need a vapor barrier under cement board?
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. It does retain moisture, but the advice given by others here is to move the waterproofing between the tile and cement board with products like Redguard or Ditra.
Can you put cement board behind a bathtub?
If the tub or shower is on an exterior wall, make sure that any piping or wiring penetrations through the walls behind the tub and enclosure are air sealed and that the wall cavities are insulated before installing cement board or equivalent. See Walls Behind Showers and Tubs for air sealing and insulating guidance.
Is cement board waterproof?
Cement board comes in the same standard sheet sizes as regular gypsum board: both are 5 feet wide, which is also the width of a standard tub surround. Unless specifically manufactured as a waterproof product, cement board is water resistant but not waterproof.
Do you need membrane under cement board?
Because fibre cement cladding is naturally very resistant against water and water exposure, there is a relatively low chance of water damage penetrating through and posing a risk to your home. The premixed fibre material acts innately as a form of resistance against water, meaning that in most cases it is not needed.
What do you put behind cement board in shower?
Unless specifically manufactured as a waterproof product, cement board is water resistant but not waterproof. You must coat it with a fluid-applied waterproofing or apply a water-resistant barrier behind it that drains (BSC 2009b).
Can cement board be attached directly to studs?
Walls: For highly wet areas, such as showers and bathtub surrounds, cement board typically is attached directly over the wall studs, although the studs may be covered with an intervening moisture membrane. (Some cement board products may not require the underlying membrane if the seams are properly waterproofed.)
Does Hardie board need a vapor barrier?
Depending on your local building authority having jurisdiction (the AHJ) over your building codes, vapor barriers are almost always required, whether your builder uses James Hardie products or some other, inferior product.
Do you need waterproof membrane on cement board?
You need to apply waterproofing over cement board in wet areas such as a shower. However, in areas that don't get wet you don't need it. Mortar, tile and grout provide some protection against water as well as the cement board itself. It's enough to resist water in areas that don't get that wet like a tiled floor.
Can you shower with just cement board?
Plastic can be used as a waterproof membrane behind a cement board. You should waterproof all shower walls before installing tiles. Although cement boards are water-resistant, most are not waterproof. Therefore, you need to apply a reliable waterproof membrane behind the cement board.
Do you leave a gap between cement board?
Leave a 1/4-inch gap between the backer board and the wall. Leave a 1/8-inch gap between each backer board sheet. The corners and edges of the sheets should not touch one another.
What goes between cement board and drywall?
For best results getting a good finish between cement board and drywall, use a setting-type joint compound. This product produces a better finish over mesh tape than all-purpose joint compound. Apply 2–3 coats of joint compound to the seam between wall boards. Wait at least 24 hours between coats of joint compound.
Should you use nails or screws for cement board?
To best attach cement boards to your project fixtures, you should use screws designed specifically for concrete board installation. When you buy cement board, the manufacturer may provide these screws with your purchase. If not, look for screws that are finished with a special coating that resists corrosion.
What happens if you don't install vapor barrier?
Without poly beneath the drywall, water vapor hits the drywall and diffuses through to the drier (in summer) indoor air. By installing a sheet of poly there, you cut off that drying mechanism and water that finds its way into walls can stay there longer and do more damage.
Do you need air gap behind Hardie board?
James Hardie requires the drainage and ventilation cavity (air gap) to be 3/8 in. (10 mm) or greater.
What do you put behind Hardie board?
Joint flashing: James Hardie recommends that a slip sheet (joint flashing) is installed behind each butt joint in the siding. This is a 6” wide piece of weather resistive material to make sure that no water gets through.
Do you need drywall behind cement board in a shower?
Water-resistant drywall isn't completely waterproof, though, and should not be used as a substitute for cement board on walls that come into direct contact with water, such as shower walls. If you want to tile over shower walls, the existing drywall has to go, and it has to be replaced with cement board.
What material goes behind shower walls?
cement boardIn showers, the standard substrate is tile backer, also called cement board or cement backer board.
Do I need to waterproof my cement board in shower?
You certainly can use a shower with cement boards without waterproofing them first, but it's not a good idea for the long term. If you plan to tile over the cement board then it is a good idea to avoid the use of soap, oils, and creams when showering.
Does cement board go behind 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.
What is waterproofing behind cement board?
plastic behind cement board with waterproofing is essentially suspenders when you already have a belt. the waterproofing is also a vapor retarder so if the red guard or kerdi product is continuous, lapping corners and all, the plastic will be unnecessary.
Why does my shower have black mold on the grout?
this is why you eventually see black mildew stains in the grout around the base of the tile - because the water is stuck back there. the redguard product is a vapor retarder which means the steam (water vapor) from the shower won't migrate thru the substrate, it will hit the waterproofing and, assuming it condenses on the colder surface migrate down along the same path noted above. in most instances, the tile is colder than the cement board, so the vapor condenses on it first and stays on the exposed surface. rather than continuous plastic sheet.
What is the best way to protect backer board from paint?
Lowes recommends installing a plastic vapor barrier behind the backer board in addition to a paint-on barrier between backer and tile. Source.
What to use for a tub that has a moisture barrier?
I usually use thick-mil plastic sheeting, overlapped in shiplap fashion (overlapping, laid down from bottom to top -- like shingles).
What is the meaning of "back up"?
Making statements based on opinion; back them up with references or personal experience.
Do you need a vapor barrier on cement board?
http://www.cityofsanmateo.org/DocumentCenter/View/200 gives some fairly good guidance. There are several kinds of backer boards. 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.
Can you put a vapor barrier behind a backer board?
You should NOT place a vapor barrier BEHIND the backer board.
What is gypsum board?
Gypsum board used as a base or backer for adhesive application of ceramic tile or other required nonabsorbent finish material must conform to ASTM C1396, C1178, or C1278. Use of water-resistant gypsum backing board is allowed on ceilings where framing spacing is 12 inches or less on center for ½-inch thick or 16 inches for 5/8-inch thick gypsum board. Water-resistant gypsum board cannot be installed over a Class I or II vapor retarder in a shower or tub compartment. Cut or exposed edges must sealed per manufacturer’s recommendations. Section R702.3.8.1 (R702.3.7.1 in 2015 and 2018 IRC) Limitations. Water-resistant gypsum board cannot be used where it will be in direct water exposure or high-humidity areas.
What is the best material to put on a shower enclosure?
Install cement board or an equivalent moisture-resistant backing material on walls behind tub and shower enclosures composed of tile or panel assemblies with caulked joints.
What is the best material for a shower?
Use an appropriate waterproof or moisture-resistant backing material behind grouted tile or stone or segmented plastic or fiberglass tub and shower surrounds. Appropriate materials include cement board which has a cementitious core ...
What tools are needed to cut cement board?
Cutting cement board requires tools different than those used for standard gypsum board; use abrasive saw blades or carbide-tipped cutters. Be sure that the framing is level and plumb before installing backer board to avoid alignment issues with premanufactured tub surrounds or tile.
Why do you need to seal the walls behind a shower?
When installing a shower or tub on an exterior wall, it is essential to air seal and insulate the wall cavities behind the shower and tub enclosure to prevent thermal bypasses that can result in moisture, heating, and cooling problems.
What is the best material for a cement board?
Equivalent materials include coated glass mat which has a gypsum core with glass fibers sandwiched between fiberglass surface mats and fiber cement which is reinforced with wood fibers.
What is R102.7.1?
Section R102.7.1 Additions, alterations, or repairs. Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with the requirements of this code, unless otherwise stated. (See code for additional requirements and exceptions.)
Why use vapor barrier on cement boards?
Cement boards are a common backing material used due to their immense durability and strength that it provides. Vapor barriers help control how moisture interacts with your materials by preventing moisture from entering critical places, such as inside your walls. The question now is if it’s necessary ...
Why are vapor barriers not recommended?
This is because the temperature difference will cause water vapor in the air to condense (when warm air collides with a cold surface).
What is the best paint for vapor retarding?
The performance of paint as a vapor barrier will highly depend on what type of paint is being used. The best paint for vapor retarding purposes would be oil-based since oil never mixes with water under normal circumstances. Glass. Glass is capable of completely blocking off water.
What is cement board?
Cement boards, also known as fiber-cement sidings, are a mixture of cement and fibers such as glass made sheets. They can be used for multiple purposes, such as adding support for walls (exterior and interior), floors, counters, etc. The main benefit and strength of cement boards are their durability.
Why are cement boards used?
They’re a good surface to work on because they can handle all sorts of stress put on them while retaining their shape.
What are the disadvantages of cement boards?
The main disadvantage of cement boards is how hard they are to work with. Remember that a big part of the costs is paying the laborers ( cement boards are difficult to cut into the right shape) in construction. The mobilizations of materials ( cement boards are heavy) and that making the material itself is quite expensive to other boards such as gypsum.
Where do you put vapor barriers?
Vapor barriers are usually installed on cement boards through their back, meaning between the board and the rest of the interior wall. Since cement boards can handle heavy loads, almost any form of a vapor barrier can be used and limited by space inside the wall cavity.
What kind of waterproofing is used for shower floor?
The shower floor would have a copper or lead pan, a rubber liner, or a “hot-mop” tar waterproofing underneath the tile. Tar paper was stapled to the walls underneath the mud.
What are moisture barriers?
What are moisture barriers? Stapling sheets of plastic or tar paper to studs is an example. Something that repels water but isn’t completely watertight.
What is the common line of thinking?
A common line of thinking is: “I’ve been doing it this way for “X” amount of years and never had a problem.”
Why is it confusing to see different membranes?
It can be confusing because even though they serve different purposes these membranes are often the same materials.
What is a mud pan?
A mud pan for a shower is a custom shower base that is sloped to the drain using a cement and sand mixture. It’s still a very common practice today although prefabricated foam shower bases are gaining in popularity. The traditional way of building a mud pan was to install a waterproof liner inside the mud bed.
Is a waterproofing membrane needed for a shower?
A waterproofing membrane, however, is a more watertight option. If you have horizontal surfaces, more extreme conditions, or simply want a heavier duty system then you’ll want a complete waterproofing membrane for your bathtub or shower.
Can you use mastic over waterproofing?
Typically, even if your tile are small enough to fit into the requirement, a normal shower has waterproofing and a mastic typically isn’t supposed to be used over a waterproofing. The issue is that it will never dry if it’s sandwiched between waterproofing and porcelain tile. Also, if it’s applied too thick.
