How far apart should screws be in cement board for floor?

Drill cement board screws through the backerboard 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.

Can I screw cement board to subfloor?

Cement board can be installed over a plywood subfloor using an appropriate construction adhesive and screws for a quicker project that’s less messy than taping and mudding.

Can you use 1/2-inch cement board on floors?

Floors. 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. … Manufacturers also recommend bonding cement board to floors with a 1/4-inch polymer-modified thinset coating.

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. … It is important to highlight that screws shall not be installed all the way down to the floor joists.

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How many screws do I need for cement board?

You will use approximately 55 screws per 3′ x 5′ cement board and 150 screws per 4′ x 8′ cement board. In wall applications, screws should be placed every 8″” when connecting to the wall studs.

What do you do with a gap between tub and cement board?

Ideally, you would leave a 1/8 inch gap which would then have the sealant applied to it. Either stopping the cement board above the tub flange or alternately shimming it out and dropping it down near the tub would both be good options.

Can you put cement board on concrete floor?

Placing cement boards over the concrete subfloor is an excellent way to create a solid and smooth subfloor. While cement backer boards are normally nailed to wood studs or a wood subfloor, you can use thin-set mortar to bond the cement boards directly to the concrete.

Do you put thinset under cement board?

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.

What thinset do I use for cement board?

Installing cement board over a wood subfloor

The good news is that, basically, any thinset mortar will work for this. Some manufacturer’s instructions say to use a modified mortar and you should follow those instructions.

Do you start tiling from the top or bottom?

Here’s how you do it: Install the first four tiles in a pyramid: three on the bottom and one on top. Every subsequent row is a process of draping over the pyramid, back and forth. Begin your first drape on either the right or left side, and bring it up, over, and down the other side.

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Should you waterproof cement board?

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

Do you need to use RedGard over cement board?

You really don’t need the RedGard, but the more protection the better…so 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. You’ll have to wait for the fills to dry or at least setup anyway.

Do you need thinset under Hardie board?

Since you are putting down hardie board on boards with small gaps, I would not recommend trying to put down thinset under it. It will make an enormous mess under the house (or whatever is under your bathroom). It is also more likely to make the floor uneven since it is hard to level thinset that is separated by gaps.