Skip to Content

Will Thinset Stick to Painted Drywall? (Read This First!)

There is a lot of speculation regarding the bond of thinset as this mortar is growing increasingly popular in the field of interior decor in recent years. People are often found concerned over whether thinset will stick to painted drywall or not.

In this article, we will address this very concern along with several other factors associated with thinset and painted drywalls. So without further ado, let’s read ahead to learn more about it.

Will thinset stick to painted drywall?

Thinset will stick to painted drywall, but it will take a longer time in the process. You cannot apply the thinset directly to painted drywall. Instead, you will have to apply an additional scratch coat, introducing a textured and solid surface on top of the painted drywall.

Different types of thinset respond differently when they are attached to painted drywall.

While you will have to follow the manufacturer’s instructions in order to ensure the best results, there are some precautions that you can take depending on the type of thinset. 

If you are dealing with an unmodified thinset, you will have to be a little more patient than you would with a modified thinset.

Let’s take a look at how unmodified and modified thinsets work when they are attached to painted drywalls.

Unmodified thinset:

Unmodified thinset will not stick to painted drywall. Since a lot of moisture gathers in the painted drywall, you will need to modify the thinset in order for it to stick well. Otherwise, the thinset will come loose after a while.

Unmodified thinset does not have a sticky layer underneath it. As a result, you will have a hard time attaching it to the moist surface of painted drywall.

Modified thinset:

you can stick a modified thinset to painted drywall. There are several versions of drywall. And if you can identify the right one for your painted drywall, then you will have a rather painless time attaching the thinset to your painted drywall.

Modified thinset is adjusted in its lowest layer. It adds an adhesive layer underneath the thinset in order to help it attach to a moist wall, including a painted drywall. So you can attach a thinset to the painted drywall quite effortlessly.

How to prep a painted drywall for thinset?

You will need to prepare your wall to attach a thinset to painted drywall. In order to prep painted drywall for thinset here are some essential steps that you will need to follow:

Scrape the wall:

The first step you need to take is to scrape the wall. You will need to remove any peeling or loose paint from the wall. This will allow you to stick thinset very smoothly to the drywall.

In addition, you will need to patch up any holes or cracks in the wall. Otherwise, the thinset will not stick properly or come loose after a while. 

Seal the walls:

Now if you’re dealing with a newly painted drywall, you will need to seal the wall with some coat. Make sure that the coat is skim.

Add some textures:

Note that painted drywalls are rather smooth. They do not have the texture that’s necessary for sticking thinsets. So during the preparation period, you should take out some time to add texture to the wall.

In order to do that, you will need to grit the wall with some sandpaper. Grit the wall for a while and it will add a very nice texture in the wall, that is not too rough but not too smooth either. This will prep the wall perfectly well.

How to thinset over painted drywall?

Thinset mortars are not originally designed to stick to painted drywalls. So you will need to take some steps in order to attach thinset over painted drywalls. Here’s what you can do:

Sand the walls:

Painted drywalls are rather smooth. This makes it hard for the thinset to stick. In order to help the thinset stick, you will need to create some textures on the wall.

You can use grit paper for this purpose. Use 80 to 120 grit paper to sand the walls and add some texture to the drywalls.

Painted drywalls are generally quite shiny after the paint job is done. In order to add texture by sanding, you will have to be persistent and keep gritting for a while. Continue the process as long as the wall is shiny.

Let the sanded wall dry:

Now that you have sanded the wall, you will need to wait for it to dry. You will need to sand the area until it is shiny. Once you are done, wait for it to dry.

Now you should wipe the sanded wall and clean off the sand from the wall. Now, wait for the wall to dry completely.

Place the thinset:

Now you will need to measure the wall and find the center point of the wall. Measure the height and width of the thinset. And measure the wall from top to bottom.

Create a horizontal line along the center that measures equal to the height of the thinset. Cover the wall with more lines of the same measurement horizontally. Now do the same for the width of the thinset, along vertical lines.

Place the first thinset in the box where both the vertical and horizontal lines meet.

What is the best thinset for painted drywall?

There are two main types of thinset. One is premixed thinset and another is dry powder thinset. The best type of thinset for drywall is a premixed thinset.

The premixed thinset comes at a relatively expensive price point. It is more expensive than the other variant of thinset. That is because it offers more convenience and comes with better offers. It is also much easier to use.

The premixed thinset is worth the cost because you can easily stick it to a painted drywall, regardless of the type of paint that was used. It simply comes in a bucket and is ready to apply right out of the package.

Will thinset adhere to latex paint? Will thinset stick to acrylic?

Yes, thinset will adhere to latex paint pretty well. Thinset will also stick to acrylic walls.

Thinset sticks well when the wall surface has some texture to it. It does not stick well if the surface is too smooth. So you will have to be careful what you are attaching the thinset to.

But rest assured thinset will attach to both latex paint and acrylic paint. But it will do so better on acrylic than on latex since acrylic paint offers a relatively more rough surface.

But note that, before you attach thinset with acrylic paint or latex painted wall, you will have to spend some time adding texture to the wall. Make sure that you have sanded the wall well with some grit paper as we have mentioned earlier.

What will thinset adhere to?

Thinset does not adhere to all kinds of surfaces. You will have to be careful with the surface on which you are attaching a thinset. Here are some of the most common surfaces that thinsets will adhere to:

New drywall:

Thinset does not stick with smooth surfaces. The mortar needs some rough texture in order to stick well. So new drywall makes the perfect surface for thinset to adhere to.

New drywalls offer the perfect texture, not too rough but not too smooth as well. It makes the task of attaching thinsets very easy for you.

Backer board:

The Backer board is another surface that makes a great choice for thinsets. Backer boards have a fine texture that will allow you to attach thinsets easily. 

It will not need any additional preparation in order for you to begin attaching thin sets because the surface will already have been prepared as it is.

Painted drywall:

Painted drywall also makes a good surface for attaching thinsets. But it will need some preparations before you can begin the process. In order to make thin sets adhere to the surface, you will need to sand the painted drywall with grit.

It will provide a nice texture to the wall that will help the thinset adhere to it better. However, the preparation period does not take too long, so you can easily go about this process without much hassle.

Final Thoughts

Thinset will stick to painted drywall without a doubt. But you will need to invest some time and effort in preparing the painted drywall. Because thinsets need a porous surface in order to adhere. So you will need to grit the painted drywall to have the perfect texture to stick thinset properly.