Table of Contents
Can you use cement board on walls?
Because cement board can be used either for floors or walls, the surface below the cement board will vary: Flooring: For ceramic tile floors, the cement board usually rests on a plywood subfloor (minimum 5/8-inch-thick exterior-grade plywood or OSB).
How do you secure cement board?
Use nails or screws as temporary spacers to create a 1/8-in. gap between sheets of cement board. When you squeeze the thin-set mortar into this gap, it will lock the two sheets together and strengthen the seam. Finally, leave extra clearance around each piece by deducting about 1/4 in.
How do you screw cement board?
Drill cement board screws through the backer board sheets every 6 to 8 inches. Position the screws at least 1/2-inch, but no more than 2 inches, from the edge of the sheet. Drive the screws in so that the heads are slightly below the surface of the backer board sheet.
How do you fill gap between cement board and drywall?
Fill the gap between the boards with mortar using the 6-inch taping knife. Force it into the gap and apply a thin layer on both sides of the joint for a total width of 3 to 4 inches. Place fiberglass mesh tape over the entire length of the joint and smooth it with the knife.
Can you use cement board instead of drywall?
Regular drywall is not appropriate either. Many professional installers even recommend against using water- or mold-resistant drywall in high-moisture areas. One solution is to nail cement backer board CBUs over the drywall, tape the seams, and then grout over the cement backer board.
Does cement board need waterproofing?
Most concrete backer-boards on the market today are not water-resistant, but all are waterproof. Since many people confuse the terms, it is a common misconception that this is the best material for use inside a shower or tub area.
Can I use drywall screws on cement board?
You don’t want to use regular drywall screws for cement boards. They can corrode, they can break down the edges of the boards, and they won’t drive in flush properly. Use ITW’s ROCK-ON and BACKER-ON screws instead.
Can I 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. It is important to highlight that screws shall not be installed all the way down to the floor joists.
Should I put thinset under cement board?
Using thinset under cement board is a commonly skipped step amongst many contractors. However, many manufacturers including, both Durock and Hardiebacker not only recommend that you use thinset under their backerboard, but they specify it and will void the warranty on their product if it’s not used.
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.
What kind of screws do I use for cement board?
Cement board attached to plywood or similar underlayment will hold with only 1 1/4-inch screws; for thick or heavy metal fixtures, use 1 5/8-inch screws. In general, 1 1/2-inch galvanized nails will hold the board firmly in place.
What do you cut cement board with?
First, you’ll want to choose a scoring tool. A carbide-tipped scoring knife is recommended, but you can also use a utility knife or shears. Never use a high-speed grinder to cut cement board indoors, since this can create a dust hazard.
What kind of thinset goes under cement board?
An unmodified thinset (Masterblend) is fine between the Hardi and the subfloor. The reason for the layer of thinset between the cement board and the subfloor is to fill the voids/gaps between the two. It’ll keep the cement board from moving up and down.
Do you have to tape cement board seams?
The thinset and mesh tape are to strengthen the seams. If you are going to tile over the cement board, you should tape the seams. This should not be that difficult.
Do you need a gap between cement board?
Stagger all HardieBacker cement board joints. Do not align with subfloor joints. Never allow all four corners of boards to meet at one point. We recommend an 1/8 in gap between board edges.
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.
Do you need green board behind cement board?
It is used for wet applications in tubs walls, shower walls, and floors. 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 RedGard on cement board?
You really don’t need the RedGard, but the more protection the betterso go for it. And yes, you can do the boards beforehand. But, hit the filled seams & screws (your weak points) as soon as a panel is ready to give it some time to setup.
