How do you tape Hardie board joints?

Asked By: Xiaoli Buemann | Last Updated: 19th June, 2020
Category: home and garden indoor environmental quality
4.9/5 (751 Views . 25 Votes)
Use special mesh tape on seams
Cut drywall to fill in between the existing wall or ceiling and the cement board. Screw the drywall to the studs. Cover all of the corners, joints and seams, including the joint where drywall and cement board meet, with the fiberglass mesh tape.

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Considering this, should you tape cement board joints?

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. If you just want to leave the corners untreated that will probably be fine, because that seam won't split the center of a tile.

Secondly, does Hardie board need waterproofing? Passing ANSI 118.10 for waterproofness, HardieBacker® 500 Waterproof Cement Board protects tile installations and wall cavities from moisture penetration, eliminating the need to spend extra time applying waterproof coating across the entire surface area of your wall project.

Beside this, do you need to tape drywall behind tile?

If you're working with new drywall, there's no need to tape the drywall joints. Seal the walls with a skim coat and let it dry thoroughly. Thoroughly vacuum the area and give the wall a once-over with a damp sponge or cleaning cloth. Allow the area to thoroughly dry before beginning tile installation.

Do you need to seal Hardibacker before tiling?

To Seal or Not To Seal Contrary to popular thought, tile and grout are not waterproof, and some moisture will penetrate even if sealant is used. If you decide to go this route, no sealant will need to be applied on top of the backerboard, as this could trap moisture between the two layers of waterproofing.

38 Related Question Answers Found

Do you have to tape durock seams?

For tile backer board 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.

Can I use drywall mesh tape for cement board?

No. The Mold-X10 fiberglass mesh tape is made for drywall seams and intended to be coated with joint compound. FibaTape's Cement Board Tape is the product for cement board. The alkali-resistant coating protects the fiberglass from degradation that can occur with thin-set mortar.

What type of screws do you 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.

Does cement board need waterproofing?

Cement boards may be classified as water resistant as in not affected by water exposure; however, they do allow penetration and passage of water and water vapor. To waterproof cement boards, a liquid or membrane waterproofing material is applied over its surface.

What kind of tape do you use for Hardibacker?


This QEP Backerboard Seam Tape Roll is self adhering to reduce application time. Can be used for seaming most types of cement backer board and tile underlayment. Fiberglass mesh for added strength.

Can I use deck screws for cement board?

There are screws made for concrete board. Bugle head like drywall screws but they are coated to resist corrosion and have sufficient strength to support the board. The heads are larger than deck screws or drywall screws, too. Rona, HD, HH will all have them.

How do you transition from cement board to drywall?

The joint between cement board and greenboard is similar to the joint between two pieces of cement board or two pieces of drywall.
  1. Plan the installation so the last column of tiles overlaps the joint between the cement board and the greenboard if possible.
  2. Mix the thin-set mortar according the instructions on the bag.

Which side of Hardie board goes out?

Cement board has a smooth side and a rough side. Face the rough side out if you will be using thin-set mortar adhesive to install the tile but the smooth side out if you will be using latex mastic.

How many screws do I need for cement board?

Fasten a minimum of 12 screws into the board (4 rows of 3 screws). Keep fixings between 15mm from board edges and 50mm from board corners.

Do I need to waterproof shower walls before tiling?


Prepping for shower tile is different than the prepping for tile on drywall. A shower is considered a wet application, so you need to waterproof the foundation, which you'll learn how to do in these instructions. After the waterproofing step, the instructions are the same as if you were installing tile on drywall.

How thick should cement board be for tile?

Cement-fiber, or similarly reinforced, backer board comes in standard 1/4 inch and 1/2 inch thicknesses. If you're installing backer board over an existing subfloor, 1/4 inch is sufficient. If you're installing backer board in new construction, attaching it directly to floor joists, opt for 1/2 inch sheets.

Do you need Thinset under cement 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.

How do you screw down cement board?

cement board screws spaced every 4 in. 4. Tape the seams Lay cement board fiberglass mesh tape over all the seams (it's sticky on one side). Use a wide putty knife or a flat trowel to spread thin-set mortar over the tape, making sure to knock down any ridges or high spots.

Is Thinset waterproof?

As Jason described, thinset itself isn't waterproof. It isn't degraded by water, and does resist the flow of water (somewhat), but definately does not "waterproof" any tile installation the way a membrane will.

Can you install cement board over drywall?


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.

How do you mud durock seams?

How to Tape Durock Joints
  1. Wipe dust and debris from the joints between the Durock panels.
  2. Cut fiberglass mesh tape to fit in a single layer over every joint where the panels meet, but do not overlap the tape.
  3. Mix powdered latex-reinforced cement mortar with water as directed on the package in a clean plastic bucket.

What's the difference between mastic and mortar?

MasticMastic is an acrylic product that can be thought of as an adhesive similar to a glue. Mastic is a non-cementitious material that exhibits some pros and cons compared to thinset. Thinset – Thinset is a cementitious product that requires water to create a chemical reaction much like concrete.