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How To Remove Thinset From Concrete Floor?

If you have worked with thinset before, then you understand just how tough it is to remove this adhesive. So if you are planning to replace your old tiles with brand new ones, then you need to have an idea of how best to remove the thinset. Luckily, we asked professionals what are the most common and best ways to remove thinset from concrete so that we can deliver the answer to you.

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When removing thinset from concrete, there are three common tools that most professionals recommend homeowners to use. These are an angle grinder, a hammer drill, and a putty knife. To remove thinset from concrete, you need to follow these basic steps:

  • Decide on which tool you will use
  • Wear a dust mask and dust protection goggles before you start working
  • Carefully chisel or grind the thinset using the tool you have decided on
  • Once done, use a vacuum or a broom with soft bristles to clean up any mess

In this article, we will explain how to use each tool properly. Additionally, we will also discuss whether there's a faster way to remove thinset and if water and vinegar help in any way. So continue reading to find out more.

A Scattered thinset on a concrete floor with mortar, How To Remove Thinset From Concrete Floor?

Why Is It Difficult To Remove Thinset?

Before we dive into the different methods, we need to understand why it's difficult to remove thinset in the first place. But first, we need to define what thinset is.

Thinset is an adhesive typically made up of cement, fine sand, and a water-retaining agent. Its main purpose is to attach a piece of tile or stone to a concrete surface. It does this job so well that it is almost impossible to remove it from the concrete afterward.

This is because thinset is valued for its strong bonding properties. And because of these properties, removing thinset from concrete is quite the challenge for any home decorator.

As seen in the images below, you can see just how thick and viscous thinset can be when mixed. Then, when applied thinly onto concrete, it becomes like tough glue that makes it difficult to remove afterward without the proper tools and method.

a man standing mixing a thinset to lay a porcelain tile floor

Methods For Removing Thinset

Now that you understand why thinset is so hard to remove, we are going to discuss the different methods used to remove it. In this section, we will explain how to use each method properly and safely. Also, be sure to wear dust protection goggles and a dust mask when attempting to remove the thinset from concrete.

hand scattering a thinset on a white concrete floor

Using An Angle Grinder

When using an angle grinder, you first need to attach a blade that's five to seven inches in diameter. If it came with a different size blade, swap it out.

Next, attach the grinder to your vacuum. This would prevent dust and dirt from getting everywhere. Don't forget to turn on your vacuum each time you use the grinder.

Then turn the grinder on. With your non-dominant hand, grip the handle of the grinder. And with your dominant hand, slowly move the grinder in a back and forth motion vertically, covering at least two to three feet.

Check this angle grinder on Amazon.

Using A Hammer Drill

First, attach a chisel bit that's two to three inches. Make sure to use a wide chisel to help remove the thinset more efficiently and quickly.

Next, set your drill to the hammer setting before holding it at a 45-degree angle using both your hands. Then, pull the trigger and gently ease the chisel against the thinset in a straight line. Don't apply too much pressure unless you arrive at some stubborn areas.

If the layer of thinset that you are about to remove is thicker than normal, decrease the angle of the hammer drill. This helps in removing the thinset while preventing harm from being done to the chisel.

Check this hammer drill on Amazon.

Chipping Away Using A Putty Knife

Prepare half a gallon of boiling water first. Add in a cup of vinegar as well before pouring the mixture all over the thinset. After around half an hour, you should start seeing cracks form all over the thinset.

Then with a putty knife, angle it against the thinset and carefully hit the base of the knife with a hammer. After half a minute, the thinset should start falling apart. You can pour in more of the boiling hot mixture to help loosen the cracks some more.

Don't forget to sharpen the putty knife once it starts getting dull. You will have to repeat this step until you removed all the thinset. With a sharp knife, the task becomes easier.

Check these putty knife scrapers on Amazon.

Using A Chemical Mastic Remover

You can easily find a mastic remover at your local hardware store. Just be sure to buy the correct kind as this chemical can easily cause damage to products that are not made of concrete.

Additionally, professionals would advise you to buy one that uses citric or acetic acid over the other kinds. They argue that a mastic remover that uses any of the two mentioned acids is much safer to use than the rest.

Carefully follow the instructions that come with the label before applying it to the thinset. Once applied, wait for around five minutes before using a putty knife or a floor scraper to scrape the thinset off.

Check this chemical mastic remover on Amazon.

Is There A Faster Way To Remove Thinset?

A thin coating of thinset mortar is smeared onto the concrete using a trowel, before the wood pieces are applied

If you want to remove thinset from a wide area, then using a floor buffing machine with an abrasive pad would work best for you. Not only would it be able to cover a large area in less time than the other methods, but it's pretty easy to use.

However, to use one, you will need to find someone willing to rent it out to you. And usually, the rental fee doesn't come cheap so it's not an economical method to remove thinset for a regular home decorator.

Do Water And Vinegar Help To Remove Thinset?

We mentioned this earlier but using a mixture of water and vinegar would greatly help in removing that stubborn thinset attached to concrete. The reason behind this is that this mixture acts as a weak solvent.

Vinegar acts as a very weak acid that's not only safe but helps create cracks into the thinset by weakening its bonding properties. In short, it is a very cheap and less effective version of a mastic remover. And adding water into the mix helps that acid get everywhere into the thinset to further spread the effects.

Additionally, warm water helps to reduce the structural integrity of the thinset. What this means is that it weakens the bonding properties of thinset, allowing for cracks to form. In turn, the warm water is allowed to get deeper into the thinset, bringing with it the vinegar that was mixed in for even more added effects.

Is It Necessary To Remove Thinset?

It's important to note that it is necessary to remove thinset from concrete when you're planning to add new tiles or wooden panels. This is to prevent the layer from creating a mess during installation.

And while it is possible to apply thinset over an old layer, you have to take into account the resulting height. Since you'll be adding a new layer on top, it won't match the rest of the flooring in terms of height. This would result in an uneven surface where parts of the flooring are raised and bumpy compared to the rest.

So before adding a layer of thinset to the concrete, make sure to properly remove the old layer first if there is one. This is to ensure a smooth installation that won't result in any breaks or cracks in the future.

Removing Thinset From Tiles

Putty knife used to scatter thinset on floor

If you accidentally applied thinset to your tiles and want to remove it, then you know that it would be a big task to undertake. And considering how fragile tiles are, the usual methods of removing thinset from concrete won't apply.

So check out this article to get a better understanding of how to carefully remove thinset from tiles: 

How To Remove Thinset From Tile [2 Methods]

In Conclusion

A Scattered thinset on a concrete floor with mortar

So if you're dealing with tough and stubborn thinset on your concrete, don't worry. There are many options available for you out there. All you need to do is find the best one that's suitable for you and you'll be scraping thinset off of the concrete like an expert in no time at all.

If you enjoyed reading this article, check the links below for related topics.

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