How I Prepped Our Basement Floor For Tile

On Wednesday, I shared a full breakdown of how I gutted the basement bathroom all by myself. Last we left, I had finally gotten the stubborn floor tile and thinset off and found a confusing surprise underneath…

Filling The Hole

Finding a hole in the ground...

Underneath a thick layer of thinset was this hole. Say what?! At first, I thought it was just some broken concrete. But upon further inspection, it had a silver ring around it and it looked like a pipe! I called my plumber, showed him the hole, and he gave me the green light to fill it up before proceeding with the floor tile. Our house was built in 1921 and this is the original foundation. When they added the bathroom down here (not sure the exact year, but guessing the 1980s or 1990s) they must have changed the plumbing around and just put tile and thinset right over the old pipe.

Using concrete patch to fill a hole in the ground

I headed to Home Depot and picked up this concrete patch material. I had never used this before, but it was pretty straightforward.

My best tips to prep concrete for floor tile

Slap it on with a trowel; let it dry for 24 hours; and then apply another coat or two if needed. That’s exactly what I did. It was super easy and my hole was gone!

Tiling Over Concrete

My best tips to prep concrete for floor tile

Okay, so the floor was clean and free of holes. Now what? Well, I did a lot of research and talked to quite a few pros to figure out what the heck to do next. In my past floor tiling projects, I’d always tiled over cement boards because the tile floors were always on plywood. This worked great.

Here, I’m in the basement and the floor is a slab of concrete on the foundation. During my research, I found that there’s a lot of debate as to if you need an underlayment between the concrete and floor tile. Some say you can tile right over the concrete (with a few extra steps to protect it from cracking), whereas others say you should do an uncoupling membrane in between.

I visited a few tile stores and talked to their pro services people to gain more knowledge. All of them said I could forego the membrane, as long as I used a floor primer on the concrete to prevent cracks and help the thinset stick to the concrete. To be honest, that sounded a bit easier and less expensive than using a membrane, so that’s the route I chose for this project.

Using A Floor Primer

Using prim grip from Mapei

I ended up picking up this prim grip, from Floor & Decor, that’s used to prep concrete for floor tile. I thought it would be similar to a wall primer, but when I opened it up, I found that the consistency was a lot thinner than paint.

Using prim grip on the floors

First, the floors need to be super clean before you can paint this stuff on. So I used my shop vac on the entire floor and then took a wet sponge to wipe up any excess dirt. This took a few passes to get things really clean. Once it was all dry, I was ready to prime it.

My best tips to prep concrete for floor tile

To apply the prim grip, you use a 3/8″ nap paint roller and roll away. I poured the liquid into a paint tray and painted it on, just as I would with regular paint. On the edges, I used a paint brush and painted it right on there. This stuff dries pretty fast, so I was able to walk on it after an hour or so.

Our bathroom all demoed and ready for tile

Now, my floor is officially ready for some tile!

What’s Next?

choosing penny tile for our basement bathroom floor

If you remember my design plan, I chose penny tile for this space and I’m so excited to show you how it turned out. I’ll be sharing a full penny tile installation tutorial on the blog on Wednesday, March 1st. This was my first time using penny tile and it had lots of pros (and a few cons) during my installation. I’ll be sure to reveal all of my best tips so you can feel confident using penny tile for your next project. It really is pretty…

Catch Up On The Basement Bathroom

My basement bathroom mood board

Out of Office

The beach at Seaside

Today, my family is heading out of town to Seaside, Florida for a little R&R. My mom is there for the entire month of February and we are heading down to get some sunshine and play with Grama. I won’t have any blog posts next week, but you can find me on Instagram, sharing some behind-the-scenes of our trip. And if you want more info about this amazing warm weather destination, I wrote a blog post all about our 2022 trip to Seaside. It was amazing.

On Monday, February 27th I’ll publish my monthly “Break Room” newsletter. If you’re on my email list, you’re good to go! If not, you can join right here. See you back on the blog on Wednesday, March 1st…


The Year of Casey

Hey there!

I’m Casey Finn, the voice behind The DIY Playbook. I’m a Chicago gal teaching you how to design, DIY, and maintain your home…by yourself! Learn more about me right here.