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How to Remove Thinset From Concrete | 2 Ways

How to Remove Thinset From Concrete | 2 Ways

Wondering how to remove thinset from concrete? You’re in the right place. While it’s an annoying problem to have, it’s also fairly easily fixed. We’ll show you the steps to take and a few things to try.


Disclaimer: The information included in this post is for informational purposes only and should not be taken as legal, financial, or DIY advice. We highly suggest consulting a professional before attempting any DIY home improvements or repairs.


So, you’ve removed most of the tiles off your floor or other tiled surface and now you’re left with a layer of mortar. In most cases, that mortar is a substance known as thinset.

Image for a guide on how to remove thinset from concrete

Joshua Rainey Photography/Shutterstock

Thinset is a mortar compound most people use to adhere tiles to concrete or cement. Knowing how to remove thinset from concrete is essential.

When you get to laying down new tiles or another type of flooring, any residual thinset will cause you to have an uneven surface. Let’s go through how to remove the thinset from concrete so you won’t have any headaches.

Removing Thinset From Concrete

There are two methods to remove thinset from concrete. The first is by using a mallet and putty knife/chisel. Although this method works, it does take the most effort. To make it easier, you can use a hammer drill, if you own one.

The second method is to use an angle grinder. Although angle grinders make the job easier, it does increase the chance you’ll damage the concrete underneath. You also need to be wary of dust particles that could be harmful to your health. 

Method 1: Mallet and Putty Knife

How to remove thinset from concrete with a mallet and a putty knife

Ioanna_alexa/Shutterstock

The hammer and putty knife method is the most labor-intensive method on this list, but you’ll get the hang of it quickly. For this method, you’ll need these materials:

  • Large stovetop pot
  • Putty knife/chisel
  • Mallet 
  • Mask
  • Belt sander or angle grinder
  • Vacuum
  • Sharpening stone (for large spaces)

Step 1: Boil Water and Pour Over Thinset

Once you’ve removed all the tile from the thinset, boil some water. You’ll need enough to cover the space with a thin layer of water. Pouring the hot water on the thinset will weaken its bonds to the concrete. Wait approximately 40 to 60 minutes, or until you see cracks from in the thinset.

Step 2: Chip Away the Thinset with the Putty Knife 

Using the putty knife or chisel, start chipping away at the thinset. To do this, place the putty knife against the thinset at a 45º angle. Then, hit the end of the putty knife with the mallet, causing the putty knife to chip away the thinset.

You don’t want to use too much force when you hit the putty knife, otherwise, you’ll damage the concrete underneath. This method should result in small chunks of the thinset breaking off. Continue removing the thinset until the concrete is smooth and free of any thinset.

Step 3: Sharpen Your Putty Knife, if Needed

Not everyone will need to sharpen their putty knife, but if you’re clearing thinset from a large space, you’ll need it. Sharpen your putty tool when you feel yourself having to hit the knife harder with the mallet.

To sharpen your putty knife, place its blade on the sharpening stone at a 20º angle and then drag the putty knife down the sharpening stone. Repeat this process on both sides of the putty knife until it can remove the thinset easily once again. 

Step 4: Remove Any Remaining Thinset

Even if you spend hours working with the putty knife, it’s difficult to remove every last piece of thinset. To remove those last remnants, the best method is to either use a belt sander or an angle grinder.

These tools will make quick work of any remaining thinset. Run the belt sander or angle grinder over the remaining thinset until the surface becomes smooth. Be careful not to breathe in too much dust, as thinset can cause lung damage. Always wear a mask and attach a HEPA filtered vacuum to tools like angle grinders, if you can. 

Alternative Step: Use a Hammer Drill

Hammer drills, sometimes known as impact drills, are tools people use to drill into hard surfaces. People also use them with chisel attachments to create what is essentially a small jackhammer. 

As you can imagine, a hammer drill makes removing the thinset much easier. To use this method, follow step one. Then, attach a chisel tool to your hammer drill. Ensure the chisel is at a 45º angle to the thinset. A 45º angle will remove most of the thinset without damaging the floor underneath. 

After you have placed the tool at a 45º angle, make sure your dominant hand is holding the back handle while your non-dominant hand grips the front handle. You shouldn’t apply pressure, instead, allow the chisel to do the work. Pull the trigger to begin hammering.

Move along one or two-foot spaces in straight lines perpendicular to the face of the chisel. You should be able to remove most of the thinset in this manner. For any remaining thinset, use an angle grinder as stated above.

Method 2: Angle Grinder

Method 2 of how to remove thinset from concrete featuring an angle grinder

Coloritmail/Shutterstock

The angle grinder method is the least labor-intensive, but it does come with added health risks. You must take precautions when you use an angle grinder to remove any thinset. You could seriously harm yourself if you’re not careful.

To remove thinset with an angle grinder, you’ll need:

  • Angle grinder
  • Diamond cutting wheel
  • Vacuum
  • Mask

Step 1: Attach Diamond Cut Wheel to the Angle Grinder

Diamond cutting wheels are the best cutting wheels to use on an angle grinder when you need to cut concrete or another stone material. These wheels have tiny synthetic diamond particles intermixed with the metal particles that make up the rest of the wheel.

By utilizing diamonds in the cutting wheel, the wheel can cut harder surfaces without dulling or breaking. So, start by attaching a diamond cutting wheel to your angle grinder.

Step 2: Attach Vacuum 

Some angle grinders allow you to attach a vacuum to the angle grinder’s dust cover. If you can do this, it is the best way to remain safe and free from thinset dust. By having the vacuum attached to the angle grinder, it will suck up any harmful dust before it reaches your lungs. 

The best type of vacuum to have in this scenario is a wet-dry vacuum that uses a HEPA filter. These filters ensure that no harmful air particles escape. Before you begin using the angle grinder, turn on the vacuum.

Step 3: Start Grinding

Hold the front handle with your non-dominant hand and hold the back of the angle grinder with your dominant hand. Turn it on. Then, without putting too much pressure on the floor, slide the angle grinder back and forth over the thinset. Hold the grinder steady so it stays in contact with the thinset. 

Grind in areas between one and two feet in length. Move along the thinset until you’re left with a smooth surface. You can go over the same spot more than once, but be careful not to dig the grinder into the concrete. 

Things to Consider

Here are some things to consider when you’re removing thinset from concrete:

  • Always wear a construction mask or respirator
  • Ensure the concrete is smooth without damaging it
  • Don’t work too fast or you may risk damaging the concrete
  • If you notice a lot of dust, damp it with water to make sure it doesn’t become airborne 
  • After you remove the thinset, clean the area thoroughly

Removing Thinset From Concrete FAQ

Tile on thinset that needs to be removed from concrete

Jorgeflorez/Shutterstock

Here are some of the most common questions we get about thinset and how to remove it from concrete:

Why Must You Remove Old Thinset?

When you tile an area of your home, you need a smooth surface. Tiles need a smooth surface so that they can adhere to the surface properly.

If the surface is uneven, the tile won’t stick to the wall or ground properly. Large, uneven surfaces can put pressure on the tile, causing cracks in the worst-case scenario. 

What’s the Difference Between Thinset and Mortar?

Thinset is a variety of mortarMortar is a general term for paste-like substances that bind things like stones, tiles, bricks, or concrete to another surface. Thinset is a type of mortar that’s made of water, sand, and concrete that people mostly use for tiling.

Is it Harder to Remove Thinset or Grout?

Grout is an adhesive substance people mainly use to fill the voids between tiling, although it does have other uses. In general, it’s much easier to remove grout, especially if you’re simply removing tile filling. You can remove it easily with a putty knife and hammer.

What’s Dangerous About Thinset Dust?

The primary danger posed by thinset and the dust it creates is a disease called silicosis. Cement is the main ingredient in thinset, and cement contains an element called silicon. When silicon dust enters your lungs, it causes severe damage over a long period. Some symptoms include:

  • Breathing difficulty
  • Persistent cough
  • Fever
  • Night sweats
  • Weight loss
  • Cancer
  • Death

Should You Hire a Professional to Remove Thinset?

You may want to hire a professional crew to take care of your thinset if the area you want to remove is large enough. The larger the area, the more thinset you’ll need to remove.

A larger area means more dust, which can cause health concerns. Think about hiring a professional crew for large spaces.

So, How Do You Remove Thinset From Concrete?

So, now that you know three methods to remove thinset, you can start right away! As you can tell, it isn’t the most complicated task. All it takes is a few tools and a little bit of effort. So, what are you waiting for? It’s time to remove those old tiles and thinset so you can put in the material you prefer!

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