How to Level a Floor for Tile in 7 Steps
Take your tiling project to the next level
- Level
- Straight edge
- Chalk or pencil
- Measuring tape
- Goggles
- Caulk
- Self-leveling compound
- Sand paper
- Thinset mortar
- Backer board
You’ve ripped out the old flooring in your kitchen or bathroom, and you’re eager to start laying the stunning new tiles you carefully picked out for the space. Not so fast! Before you can start spreading mortar, spacing tile, and applying grout, you need to make sure you’re giving your tile the best possible base, or you risk damaging the tiles in the long run. Here’s how to level a floor for tile installation like a pro—plus who to call if this project seems too overwhelming.
Prepping to Level Floors for Tile
Before you start inspecting for uneven spots on the subflooring, there are a few prep tasks to check off your list. First, make sure to scrape off or pull up any excess adhesive, old mortar, or other debris. Sweep the entire area to ensure the floors are clean and ready for inspection and leveling.
You’ll also need to make repairs to any loose wood subfloor planks or cracks in a concrete subfloor. If you decide you need to replace your subfloors, it’s best to tap a flooring pro, since faulty subfloors can cause problems for your tiles in the long run.
How to Level a Floor for Tile
Laying tile on an uneven floor means you’ll be dealing with tile repairs very soon after installation. In order to save yourself the money and grief of redoing your beautiful tile floors, you’ll need to put in the extra effort of smoothing out the floor first. Leveling a floor before you lay tile involves measuring low spots, sealing gaps and seams, applying self-leveling compound, sanding down high spots, and applying a backer board (if needed). Here’s how to do it.
Check for Low Spots With a Straight Edge
Photo: Niko_Dali / Adobe StockUsing a straight edge that’s at least four feet long, place the tool on the floor. As the name implies, the straight edge should sit straight along the floor, but if you notice any gaps, that identifies a low spot. If the tool is raised in some areas, that is evidence of a high spot.
Use chalk, a pencil, or another writing tool to mark any low points and high points. Repeat with the straight edge until you’ve checked the entire room.
Measure the Dips
Once you’ve noted where the low points are in the floor, use a measuring tape to note how deep these divots go. Jot down the measurements. This information will help you determine how much material you need to properly fill the low points.
Fill Seams
Photo: Maryana Serdynska / iStock / Getty ImagesIf you’re working with wood subfloors, use caulk to seal any gaps, cover nails, and fill the seams between wood planks. This will help create the smoothest surface possible after you apply a self-leveling compound to the subfloors.
Apply Self-Leveling Compound
You can find self-leveling compound at a home improvement store, and this material will be your best friend in leveling a floor for tile installation. Suit up in your protective gear, then mix the self-leveling compound in a bucket according to the product instructions. Pour the resulting mixture in the low areas, spreading it out with a trowel. Follow the dry time listed in the instructions.
Sand or Grind Away High Spots
Head to the areas you marked as high spots while donning your protective gear, including gloves, a mask, goggles, and work boots. For wood subfloors, use a belt sander to sand down the high points. For concrete subfloors, you’ll need to rent a cement grinder to smooth out the peaks.
Revisit the areas you filled with self-leveling compound once the compound is fully dry. If there is too much compound in some areas, use the sander or grinder to smooth out these areas. Make sure to clean up the area with a wet-dry vacuum afterward to ensure the flooring is as clean and level as possible.
Apply a Backer Board as Needed
For wood subfloors, you can further ensure the most level surface possible by installing backer board. Using a backer board scoring tool, cut the backer board to the correct size to fit the space. Then, you’ll apply a thinset mortar to the subfloor with a trowel, creating notches with the notched end of the trowel for better adhesion. Lay each piece of backer board onto the mortar.
To finish installing the backer board, use a drill to screw the perimeter of the backer board into the wood subfloors. Place a screw about every eight inches, or follow the guided markings on the backer board. Stagger the boards, so the end of one board isn’t aligned with the edge of another board.
Use fiberglass tape to cover the backer board joints, then use the trowel to cover the tape with thinset mortar. If you choose to install backer board, it needs an extra one to two days for the thinset mortar to fully dry before you can begin tiling.
Clean the Area and Prepare to Lay Tile
Photo: Andrea Kessler / iStock / Getty ImagesOnce the floors are thoroughly leveled, make sure to pass through the room with a wet-dry vacuum to clean up any debris that kicked up while you worked. Once the materials are fully dry and the room is clean, you can begin the tile installation process.
DIY vs. Hiring a Pro
For DIY floor leveling, you’ll spend at least $350 to $400 on the self-leveling compound needed to cover about 350 square feet of space. Backer board will cost another $5 to $10 per square foot, plus you’ll need to purchase thinset mortar, screws, and fiberglass tape to install backer board.
If you don’t own a cement grinder, renting one costs about $100 to $200 per day. Buying a belt sander for wood subfloors costs about $50 to $120, while renting a floor sander costs about $30 per day.
Installing tile floors costs about $1,900 on average for professional installation, with floor leveling costing an additional $2 to $30 per square foot. It may be more cost-effective, not to mention time-saving, to hire a pro for floor leveling and tile installation.
Leveling a floor for tile is a suitable DIY project for handy homeowners, but it requires several tools—like a belt sander or cement grinder—and supplies to get the job done. If you don’t feel confident in tackling this project, call a local tile installer right away to make light work of this important task.
Frequently Asked Questions
Your floors should be completely level for tile, otherwise you risk damaging the tiles in the future. When there are even small gaps or hills in the subfloor beneath the tile, this puts more pressure on the tile when you walk around on the floor. With repeated traffic, the tiles are at risk of cracking, and you’ll have to deal with tile repairs sooner than if the floor was completely level.
Self-leveling compound usually requires up to 24 hours to dry before you can begin installing tile. It’s best to follow the instructions on the self-leveling product label for appropriate dry time. If you’re still not sure, play it safe and give the self-leveling compound two days to dry before you begin the tiling process.
While you shouldn’t use thinset mortar on its own as a floor leveler, it can work alongside other products to help level floors. For instance, you could start with a self-leveling compound, let that dry, then apply backer board with thinset mortar to help fully even out the floors ahead of laying tile.
