Removing Backer Board From Subfloor? 102 Most Correct Answers

Cement board, commonly sold under trade names such as Durock, Hardiebacker and WonderBoard, is now the standard backing for ceramic, porcelain or stone tiles laid with thin mortar adhesive. Cement board is used for most floor tiling and has almost entirely replaced plywood and drywall substrates for wall tiling applications in wet areas such as showers and tub surrounds.

Cement board provides a durable, stable base for tiles and contains no organic materials (unlike drywall, greenboard, or plywood), so it is not susceptible to mold, rot, shrinkage, or degradation from moisture. Ceramic tile laid on cement board is one of the most durable floor or wall finishes you can lay.

The surface under the cement board

Because cement board can be used for either floors or walls, the surface under the cement board varies:

Flooring: For ceramic tile floors, the cement board typically rests on a plywood subfloor (at least 5/8 inch thick plywood or OSB for outdoor use). When installing new ceramic tiles over an existing floor, the cement board can usually be laid directly over the existing flooring provided the floor is in good condition and the extra thickness is not a problem. There is no need to install a backing plate on a concrete substrate – ceramic tiles can be applied directly to concrete provided the surface is flat, smooth and free from significant cracks.

With ceramic tile floors, the cement board typically rests on a plywood subfloor (at least 5/8 inch thick plywood or OSB for outdoor use). When installing new ceramic tiles over an existing floor, the cement board can usually be laid directly over the existing flooring provided the floor is in good condition and the extra thickness is not a problem. There is no need to install a backing plate on a concrete substrate – ceramic tiles can be applied directly to concrete provided the surface is flat, smooth and free from significant cracks. Walls: For high-humidity areas, such as shower and bathtub environments, cement boards are usually placed directly over the wall studs, although the studs may be covered with an intervening moisture membrane. (Some cement board products may not require an underlying membrane if the seams are properly watertight.) Never install cement board directly over drywall or greenboard in such wet areas. Instead, first remove the existing surfacing material and then install the cement board over the studs and membrane if applicable.

sizes

Cement board is most commonly sold in 3 x 5 foot boards and in thicknesses from 1/4 inch to 5/8 inch. A 3 x 5 sheet of 1/4 inch cement board weighs about 30 pounds; a 1/2 inch sheet, 36 to 44 pounds. Larger 4 x 8 foot panels are also available, but their weight makes them difficult to handle for DIYers.

Choose a sheet thickness based on the application:

Floors: A minimum thickness of 1/4 inch is required, but thicker boards are fine too.

A minimum thickness of 1/4 inch is required, but thicker boards are fine too. Walls: Use 1/2 inch or 5/8 inch thick cement board, not 1/4 inch. The extra thickness is needed when spanning the studs and provides a solid base for the tile.

Use 1/2 inch or 5/8 inch thick cement board, not 1/4 inch. The extra thickness is needed when spanning the studs and provides a solid base for the tile. Countertops: 1/4 inch, 1/2 inch or 5/8 inch thick board are all suitable for countertops.

before you start

You’ll need to cut your cement board to different sizes to fit your project and knowing how before you start your project will help you avoid costly mistakes.

You can cut the cement board with a utility knife and a T-square. Score the cement board deeply with two or three passes with the knife, use the angle bar to ensure a straight line, and then snap back the excess area of ​​the board to break the board along the cut line. If applicable, cut the fiberglass cloth along the back of the panel to complete the cut.

For round or curved cuts, use a jigsaw with a carbide blade or drill and hole saw bit.

3:01 Click play to learn how to properly install Cement Board

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Installing cement board is not incredibly difficult.

I think most people worry about how to cut it and once they have a plan for it they think it will be a piece of cake.

But I’ve been seeing these errors for a number of years. It’s always the same.

Estimated reading time: 6 minutes

What products are we talking about?

Common mistakes when installing cement board

The products I am talking about are mainly considered as cement backing boards for laying tiles.

These come in two categories: cement board and fiber cement board.

Examples of cement boards are: Wonderboard, Durock and Permabase

Examples of fiber cement panels: Hardibacker and Fiberock,

Let me add a disclaimer here: These are general guidelines. Each manufacturer has their own instructions for their own products and they will vary slightly.

So the moral of this story is to read the instructions and not just this post.

Cement board installation is not just limited to these 5 ways

Now there are more ways to screw things up than just these five things. This actually assumes that your wooden subfloor meets the minimum requirements.

Tip: Cement board should never count on stiffening your floor. The floor must meet minimum tile requirements PRIOR to installing a tile backing board.

However, these are the five that stood out the most in my unofficial memory.

Here you are:

Cement board seams require mesh tape and thinset

1. No thinset under the carrier plate

Just the other day I saw a video of someone mounting Hardibacker directly to the subfloor with nothing underneath. I scrolled down to see the comments and they didn’t disappoint. What were his answers you ask?

“The thin set is placed on the TOP of the cement board to glue the tiles!”

A simple reading of the instructions would show otherwise. But most people don’t look at them – not even the pictures.

Also, I know some are wondering, but no, Liquid Nails don’t count as thinset replacements. We must remember that this is not the same as laying plywood. Cement board is a different product and needs to be installed in its own way.

Also, screws don’t replace Thinset either. I talk more about screws in #3.

What kind of thinset do I need for installation under cement board?

Here’s the good news: It doesn’t matter what brand or type of thin-set mortar you buy. I know manufacturers want you to use their own brand and maybe even specify a type. If yes, then you should buy what you need.

But the system works by having a bed of mortar underneath that holds the slab up and fasteners from above that hold the slab down. You don’t need a fancy mortar to accomplish this task, and many will use an unmodded mortar in this situation.

Also, when mixing thinset for backing board installation, it doesn’t hurt to add a little more water to make it a little looser.

Panels can be laid either way as long as the seams are staggered

2. No staggering of the seams

Well, this is an area that the plywood installers will be familiar with. You don’t want four cement board corners all coming together in an intersection.

You get around this by offsetting the planks during installation. One beautiful thing about tile backing sheets is that it doesn’t matter which way you lay the sheets.

You can let them run one way or the other, but as long as the corners don’t all come together, it’s fine. Also, you don’t want the cement board seams to match the subfloor seams.

Those are the two things to look out for when installing cement board.

3. Fasteners

Most cement board manufacturers require galvanized roofing nails or cement board screws.

But that doesn’t stop people from using ring shank nails, drywall screws, or who knows what else?

The problem is that these fasteners don’t have the holding power that cement board screws and roofing nails do.

Some examples of the different cement board screws on the market

Additionally, people mess up fasteners by not using enough of them and driving them in too deep.

It’s usually every 8 inches throughout, but there are some differences between brands. Some carrier plates have the mounting positions printed on the plate.

4. Do not use mesh tape on the seams of your cement board installation

This is rather a little known fact, but most cement board manufacturers want an alkali resistant fiberglass cloth tape embedded in thin set mortar over the seams of the backing boards.

Mesh Tape: Don’t skip this step

I remember a time when this wasn’t a requirement, but it has been in recent years.

5. Installing cement slabs on a concrete subfloor

If you have a concrete subfloor, don’t think about laying cement slabs over it.

I know it looks like a smooth surface and it seems like it might fix some of the concrete floor problems, but don’t.

Self-Leveling Underlay: The Ultimate Guide

Thinset is not only a critical component among cement boards, but the other critical component is the fasteners. And you don’t have any fasteners if you try to install it on concrete.

On the plus side, there are some concrete subfloor options. One of them is self-leveling underlay and other floor smoothing products.

The other is a foam backing board that can be attached to concrete. This can be beneficial if you want to insulate concrete from an overlying electric underfloor heating system.

Install electric underfloor heating: Ignore these two rules

Check with Wedi, Schlueter, Laticrete, GoBoard or any other manufacturer to learn how they plan to install their product on a concrete subfloor.

Award

I know there are more ways to screw up cement board installation than just these five.

I might list incorrect trowel size, thin set mixed too thick, thin set allowed to skin and others.

You tell me in the comments: Which ones do I miss? What errors do you see?

Backer Board is a product made of cement. Typically 1/2 inch thick, it is screwed onto the plywood subfloor before the tiles are installed. It ensures an even surface of the tile. If you previously removed tiles, the backer is next. Removing the backing plate is not complicated. It’s dirty work, but someone has to do it before subsequent flooring can be installed. All you need are a few hand tools.

Do-it-yourselfers rely on cement backing board for numerous projects, including tiled walls, floors, and even countertops. Stronger than plywood and less susceptible to damage from rot, cement backing board is a more reliable, durable building material than wood. However, its strength and cement construction pose more challenges than engineered wood when it comes time to make the cut. Luckily, with the right tools, techniques, and a little patience, you can cut through this tough material.

before you start

A word of caution before you begin: As with any home maintenance project, proper protection should be used when cutting cement backing board. Before you begin, make sure you put on both eye goggles and a respirator. Cutting through the cement creates dust that can be dangerous if you breathe it in or get it in your eyes.

METHOD 1: Score and snap thinner sheets

One of the easiest techniques for cutting cement backing board is to score the board and then snap it along the cut line.

Lay your cement board flat and use a carpenter’s pencil to draw a line where you want to cut. Place a ruler along the line and draw against it with either a drywall knife or scoring tool. Repeat your cuts 2-3 times to make them deeper, which will make it easier for the board to snap into place. When you’re done with your cuts, stand the board up and push your knee behind the line you scored. A little pressure will cause the section of board to split leaving the fiberglass mesh intact. Cut apart the connecting mesh with a utility knife.

METHOD 2: Cut straight lines with a circular saw

For slightly smoother and more efficient cuts, turn to power tools. While more commonly used for cutting wood, circular saws can also make quick, clean cuts in cement board—and are often conveniently at hand in the workshops of DIY-savvy homeowners. Equip your circular saw with a carbide-tipped wood saw blade (see example on Amazon) and choose one with as few teeth as possible to minimize dust generation when sawing. Operate your circular saw as usual, slowly and steadily pushing it through your cement backing board.

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For DIYers who need small round holes for cord or pipe, there are a few tool options.

MASONRY BIT

One method involves using an electric drill fitted with a stone chisel. Because masonry drill bits come in a variety of sizes, it’s easy to find one that’s the exact size you need.

Simply attach the drill to the drill bit, use a carpenter’s pencil to mark the area that needs to be cut, and drill the drill bit into the cement board. With a little pressure, the drill cuts through the carrier board.

PUZZLE

A jigsaw fitted with a metal cutting blade or a carbide grit blade can make larger rounded cuts in addition to the normal straight cuts.

If you’re using a jigsaw for the job, it’s important to first mark the board with a carpenter’s pencil for guidance. Start the process by drilling a hole with a masonry bit, then use the jigsaw to widen it and continue the work.

While cutting round holes with a jigsaw is more difficult than using a rock chisel, the process allows for a more customized hole size.

Backer Board is a product made of cement. Typically 1/2 inch thick, it is screwed onto the plywood subfloor before the tiles are installed. It ensures an even surface of the tile. If you previously removed tiles, the backer is next. Removing the backing plate is not complicated. It’s dirty work, but someone has to do it before subsequent flooring can be installed. All you need are a few hand tools.

You can remove thinset from plywood with a few simple tools. Credit: tomazl/iStock/GettyImages See more photos

Thinset is a type of mortar used as an adhesive in flooring projects. It is very strong and will keep your floors intact for many years. However, if you are removing tile adhesive from a plywood subfloor or replacing your flooring and need to strip the top layers down to the base or underlay, you will likely need to remove the thin layer from your plywood underlay. Luckily, with a little elbow grease and a few simple tools to remove Thinset from a concrete or plywood floor, this is possible.

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video of the day

Thinset Material Basics

According to Tile Outlet, Thinset is used to lay tiles on cement, fiberboard and waterproof membranes. Thinset makes it possible for the tiles or stones you use to stick to the base, which is often made of plywood.

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Thinset contains cement so it is extremely durable and ideal for holding flooring in place. It is also composed of fine sand and a binder such as latex or polymers and a water retention agent such as an alkyl derivative of cellulose.

Prepare to remove Thinset

The first step in removing thinset from a plywood backing is to remove the top layer of flooring. This can be tile or stone. Always use eye protection and a dust mask when removing tiles or stones. It is ideal to wear robust work gloves and also to use hearing protection to protect hands and ears.

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After removing the top layers of soil, thoroughly clean the area. You may want to use a broom to sweep up dirt and then use a vacuum to remove fine dust. This makes it easier for you to see if you have successfully removed the entire thinset.

Removing thinset from plywood

Use a hammer and, if necessary, a chisel to hit the thin film repeatedly to loosen it from the sub-floor. Be careful not to hit the floor too hard or you may damage the underbody. When detaching the thinset, use a metal scraper to remove it from the floor. It can be helpful to have a garbage bag or bucket nearby to dump loose bits of thin bed.

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Continue scratching the thin set, following the gaps created where pieces broke off. The process can be a little tedious, but you’ll likely find that it’s easiest if you follow the pattern of hammering and chiseling to loosen the material, then scraping out the holes left by the broken pieces . Continue cleaning up as you go.

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Using the thinset removal blade

You will likely need to use a sharp scraper or thin wood stripping blade to get at hard bits of thin material that are difficult to remove from the plywood subfloor. If you still have runny bits that you can’t remove, you can use coarse sandpaper, either by hand or on an electric sander, to sand down to the wood. It is important that your subfloor is as clear as possible before attempting to swap out the upper floor levels.

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Prepare plywood for new floors

After removing the entire thin layer, vacuum up any residue that is left behind. It is important that your plywood subfloor does not have any lumps or bumps as these can make installing a new floor difficult and result in an inferior end product.

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After all residue has been removed, wash the plywood sub-floor thoroughly with soap and water. Give it time to dry; Ideally, you should wait several days before installing another type of underlay or flooring. If you don’t allow the floor time to dry, mold can grow on the plywood and compromise the structural integrity of the floor. In addition, inhaling mold is harmful and can lead to health problems, especially if you suffer from allergies or asthma.