How do you seal the edges of cement board?
Quote from the video:
Quote from Youtube video: This area right here what you wanna do is you want to take some of the thin set mortar you want to just put it on the teeth and then sweep it off so that you get a nice thin layer on the teeth.
Do you need a vapor barrier behind 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.
What do you put on the corners of cement board?
Use special mesh tape on seams
Cover all of the corners, joints and seams, including the joint where drywall and cement board meet, with the fiberglass mesh tape.
Does cement board need an expansion gap?
Leave a 1/8-inch gap between each backer board sheet. The corners and edges of the sheets should not touch one another.
What do you do with a gap between tub and cement board?
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.
How do you fill gap 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.
Do you put drywall behind cement board?
(Some cement board products may not require the underlying membrane if the seams are properly waterproofed.) 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.
Do you need green board behind cement board?
So, remember green board for damp areas but cement board for all areas that could possible come in direct contact with water to ensure the longest life of your bath and tile needs.
Do you need to use Redgard over cement board?
No, you don’t need to apply Redgard over your Hardibacker. Here’s why: Redgard works best on cement boards and plywood because it prevents water from seeping into those surfaces. It can also work on top of drywall that isn’t behind a tub or shower, but it will eventually wear off after repeated moisture exposure.
Can you just screw down cement board?
Screw and Joints
Do not use drywall screws as they are not recommended to be used to hold the backer board in place. All of your backer board pieces should be cut before they are placed on the floor. Along the perimeter, screws should be installed at least ½ inch from the edge, but no more than 2 1/4 inches.
Can you walk on cement board after installation?
This is normally 12 hours but may be up to 24 hours in some cases. After the mortar is dry the backer board is ready to receive the mortar for the tile.
How much gap do you need between durock?
And the 2-inch gap between the durock and the floor is there to prevent “whicking” for the durock that is not actually waterproof. So, there is no membrane, and the 2-inch gap is in keeping with the code. And that it is actually the tile and the grout that make things waterproof.
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.
What thinset do I use for cement board?
The cement board is then screwed into the plywood while the thin-set is fresh/wet. MAPEI recommends the use of MAPEI Porcelain Tile Mortar, MAPEI Large-Format Floor & Wall Tile Mortar or MAPEI Large Tile & Stone Mortar as thin-set under the cement board.
Why do I need thinset under backer board?
Thinset is going to create a solid surface under tile and prevent flexing that could lead to cracking. Using thinset between the backerboard and subfloor will create additional strength, fill in any potential gaps that exist and lessen the possibility of movement.
Do you have to tape seams on Hardibacker?
For tile backer boards such as Durock, Wonderboard, Hardiebacker, Permabase, and others the seams between the board need to be treated with 2-inch alkali-resistant mesh tape. Then a coat of thinset gets flat troweled over the seam. What this does is tie the two boards together and help prevent flexing.
